Federal Register, Volume 88 Issue 128 (Thursday, July 6, 2023)

[Federal Register Volume 88, Number 128 (Thursday, July 6, 2023)]
[Proposed Rules]
[Pages 43174-43246]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-13622]

[[Page 43173]]

Vol. 88

Thursday,

No. 128

July 6, 2023

Part II

Department of Transportation

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National Highway Traffic Safety Administration

Federal Motor Carrier Safety Administration

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49 CFR Parts 393, 396, 571, et al.

Heavy Vehicle Automatic Emergency Braking; AEB Test Devices; Notice of
Proposed Rule

Federal Register / Vol. 88, No. 128 / Thursday, July 6, 2023 /
Proposed Rules

[[Page 43174]]

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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Parts 571 and 596

[Docket No. NHTSA-2023-0023]
RIN 2127-AM36

Federal Motor Carrier Safety Administration

49 CFR Parts 393 and 396

[Docket No. FMCSA-2022-0171]
RIN 2126-AC49

Heavy Vehicle Automatic Emergency Braking; AEB Test Devices

AGENCY: National Highway Traffic Safety Administration (NHTSA), Federal
Motor Carrier Safety Administration (FMCSA), Department of
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This NPRM proposes to adopt a new Federal Motor Vehicle Safety
Standard (FMVSS) to require automatic emergency braking (AEB) systems
on heavy vehicles, i.e., vehicles with a gross vehicle weight rating
greater than 4,536 kilograms (10,000 pounds). This notice also proposes
to amend FMVSS No. 136 to require nearly all heavy vehicles to have an
electronic stability control system that meets the equipment
requirements, general system operational capability requirements, and
malfunction detection requirements of FMVSS No. 136. An AEB system uses
multiple sensor technologies and sub-systems that work together to
sense when the vehicle is in a crash imminent situation and
automatically applies the vehicle brakes if the driver has not done so
or automatically applies more braking force to supplement the driver's
applied braking. This NPRM follows NHTSA's 2015 grant of a petition for
rulemaking from the Truck Safety Coalition, the Center for Auto Safety,
Advocates for Highway and Auto Safety and Road Safe America, requesting
that NHTSA establish a safety standard to require AEB on certain heavy
vehicles. This NPRM also responds to a mandate under the Bipartisan
Infrastructure Law, as enacted as the Infrastructure Investment and
Jobs Act, directing the Department to prescribe an FMVSS that requires
heavy commercial vehicles with FMVSS-required electronic stability
control systems to be equipped with an AEB system, and also promotes
DOT's January 2022 National Roadway Safety Strategy to initiate a
rulemaking to require AEB on heavy trucks. This NPRM also proposes
Federal Motor Carrier Safety Regulations requiring the electronic
stability control and AEB systems to be on during vehicle operation.

DATES: Comments must be received on or before September 5, 2023.
Proposed compliance dates: NHTSA proposes a two-tiered phase-in
schedule for meeting the proposed standard. For vehicles currently
subject to FMVSS No. 136, ``Electronic stability control systems for
heavy vehicles,'' any vehicle manufactured on or after the first
September 1 that is three years after the date of publication of the
final rule would be required to meet the proposed heavy vehicle AEB
standard. For vehicles with a gross vehicle weight rating greater than
4,536 kilograms (10,000 pounds) not currently subject to FMVSS No. 136,
any vehicle manufactured on or after the first September 1 that is four
years after the date of publication of the final rule would be required
to meet the proposed AEB requirements and the proposed amendments to
the ESC requirements. Small-volume manufacturers, final-stage
manufacturers, and alterers would be provided an additional year to
comply with this proposal beyond the dates identified above.
FMCSA proposes that vehicles currently subject to FMVSS No. 136
would be required to comply with FMCSA's proposed ESC regulation on the
final rule's effective date. Vehicles with a GVWR greater than 4,536
kilograms (10,000 pounds) not currently subject to FMVSS No. 136 would
be required to meet the proposed ESC regulation on or after the first
September 1 that is five years after the date of publication of the
final rule.
FMCSA proposes that, for vehicles currently subject to FMVSS No.
136, any vehicle manufactured on or after the first September 1 that is
three years after the date of publication of the final rule would be
required to meet FMCSA's proposed AEB regulation. FMCSA proposes that
vehicles with a gross vehicle weight rating greater than 4,536
kilograms (10,000 pounds) not currently subject to FMVSS No. 136 and
vehicles supplied to motor carriers by small-volume manufacturers,
final-stage manufacturers, and alterers would be required to meet the
proposed AEB regulation on or after the first September 1 that is five
years after the date of publication of the final rule.
This proposed implementation timeframe simplifies FMCSR training
and enforcement because the Agency expects a large number of final
stage manufacturers supplying vehicles to motor carriers in the
category of vehicles with a gross vehicle weight rating greater than
4,536 kilograms (10,000 pounds).
FMCSA's phase-in schedule would require the ESC and AEB systems to
be inspected and maintained in accordance with Sec. 396.3.
Early compliance is permitted but optional.

ADDRESSES: You may submit comments to the docket number identified in
the heading of this document by any of the following methods:
Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the online instructions for submitting
comments.
Mail: Docket Management Facility, M-30, U.S. Department of
Transportation, West Building, Ground Floor, Rm. W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.
Hand Delivery or Courier: West Building, Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, between 9 a.m. and 5 p.m.
Eastern Time, Monday through Friday, except Federal holidays. To be
sure someone is there to help you, please call 202-366-9332 before
coming.
Fax: 202-493-2251.
Regardless of how you submit your comments, please provide the
docket number of this document.
Instructions: For detailed instructions on submitting comments and
additional information on the rulemaking process, see the Public
Participation heading of the Supplementary Information section of this
document. Note that all comments received will be posted without change
to https://www.regulations.gov, including any personal information
provided.
Privacy Act: In accordance with 5 U.S.C. 553(c), DOT solicits
comments from the public to better inform its decision-making process.
DOT posts these comments, without edit, including any personal
information the commenter provides, to https://www.regulations.gov, as
described in the system of records notice (DOT/ALL-14 FDMS), which can
be reviewed at https://www.transportation.gov/privacy. In order to
facilitate comment tracking and response, the agency encourages
commenters to provide their name, or the name of their organization;
however, submission of names is completely optional. Whether or not
commenters identify themselves, all timely comments will be fully
considered.
Docket: For access to the docket to read background documents or

[[Page 43175]]

comments received, go to https://www.regulations.gov, or the street
address listed above. To be sure someone is there to help you, please
call 202-366-9322 before coming. Follow the online instructions for
accessing the dockets.

FOR FURTHER INFORMATION CONTACT: NHTSA: For non-legal issues: Hisham
Mohamed, Office of Crash Avoidance Standards (telephone: 202-366-0307).
For legal issues: David Jasinski, Office of the Chief Counsel
(telephone: 202-366-2992, fax: 202-366-3820). The mailing address for
these officials is: National Highway Traffic Safety Administration,
1200 New Jersey Avenue SE, Washington, DC 20590. FMCSA: For FMCSA
issues: David Sutula, Office of Vehicle and Roadside Operations
Division (telephone: 202-366-9209). The mailing address for this
official is: Federal Motor Carrier Safety Administration, 1200 New
Jersey Avenue SE, Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary
II. Safety Problem
III. Efforts To Promote AEB Deployment in Heavy Vehicles
A. NHTSA's Foundational AEB Research
B. NHTSA's 2015 Grant of a Petition for Rulemaking
C. Congressional Interest
1. MAP-21
2. Bipartisan Infrastructure Law
D. IIHS Effectiveness Study
E. DOT's National Roadway Safety Strategy (January 2022)
F. National Transportation Safety Board Recommendations
G. FMCSA Initiatives
IV. NHTSA and FMCSA Research and Testing
A. NHTSA-Sponsored Research
1. 2012 Study on Effectiveness of FCW and AEB
2. 2016 Field Study
3. 2017 Target Population Study
4. 2018 Cost and Weight Analysis
B. VRTC Research Report Summaries and Test Track Data
1. Relevance of Research Efforts on AEB for Light Vehicles
2. Phase I Testing of Class 8 Truck-Tractors and Motorcoach
3. Phase II Testing of Class 8 Truck-Tractors
4. NHTSA's 2018 Heavy Vehicle AEB Testing
5. NHTSA's Research Test Track Procedures
6. 2021 VRTC Testing
C. NHTSA Field Study of a New Generation Heavy Vehicle AEB
System
D. FMCSA-Sponsored Research
V. Need for This Proposed Rule and Guiding Principles
A. Estimating AEB System Effectiveness
B. AEB Performance Over a Range of Speeds Is Necessary and
Practicable
C. Market Penetration Varies Significantly Among Classes of
Heavy Vehicles
D. This NPRM Would Compel Improvements in AEB
E. BIL Section 23010(b)(2)(B)
F. Vehicles Excluded From Braking Requirements
VI. Heavy Vehicles Not Currently Subject to ESC Requirements
A. AEB and ESC Are Less Available on These Vehicles
B. This NPRM Proposes To Require ESC
C. BIL Section 23010(d)
D. Multi-Stage Vehicle Manufacturers and Alterers
VII. Proposed Performance Requirements
A. Proposed Requirements When Approaching a Lead Vehicle
1. Automatic Emergency Brake Application Requirements
2. Forward Collision Warning Requirement
i. FCW Modalities
ii. FCW Auditory Signal Characteristics
iii. FCW Visual Signal Characteristics
iv. FCW Haptic Signal Discussion
3. Performance Test Requirements
4. Performance Test Scenarios
i. Stopped Lead Vehicle
ii. Slower-Moving Lead Vehicle
iii. Decelerating Lead Vehicle
5. Parameters for Vehicle Tests
i. Vehicle Speed Parameters
ii. Headway
iii. Lead Vehicle Deceleration Parameter
6. Manual Brake Application in the Subject Vehicle
B. Conditions for Vehicle Tests
1. Environmental Conditions
2. Road Service Conditions
3. Subject Vehicle Conditions
C. Proposed Requirements for False Activation
1. No Automatic Braking Requirement
2. Vehicle Test Scenarios
i. Steel Trench Plate
ii. Pass-Through
D. Conditions for False Activation Tests
E. Potential Alternatives to False Activation Tests
F. Proposed Requirements for Malfunction Indication
G. Deactivation Switch
H. System Documentation
I. ESC Performance Test
J. Severability
VIII. Vehicle Test Device
A. Description and Development
B. Specifications
C. Alternatives Considered
IX. Proposed Compliance Date Schedule
X. Retrofitting
XI. Summary of Estimated Effectiveness, Cost, Benefits, and
Comparison of Regulatory Alternatives
A. Crash Problem
B. AEB System Effectiveness
C. ESC System Effectiveness
D. Avoided Crashes and Related Benefits
E. Technology Costs
F. Monetized Benefits
G. Alternatives
XII. Regulatory Notices and Analyses
XIII. Public Participation
XIV. Appendices to the Preamble
A. Description of Technologies
B. International Regulatory Requirements and Other Standards

Abbreviations Frequently Used in This Document

The following table is provided for the convenience of readers for
illustration purposes only.

Table 1--Abbreviations
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Abbreviation Full term Notes
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ABS................. Antilock Braking Automatically controls the
System. degree of longitudinal wheel
slip during braking to prevent
wheel lock and minimize
skidding by sensing the rate
of angular rotation of each
wheel and modulating the
braking force at the wheels to
keep the wheels from slipping.
AEB................. Automatic Applies a vehicle's brakes
Emergency automatically to avoid or
Braking. mitigate an impending forward
crash.
CIB................. Crash Imminent Applies automatic braking when
Braking. forward-looking sensors
indicate a crash is imminent
and the driver has not applied
the brakes.
CMV................. Commercial Motor Has the meaning given the term
Vehicle. in 49 U.S.C. 31101.
CRSS................ Crash Report A sample of police-reported
Sampling System. crashes involving all types of
motor vehicles, pedestrians,
and cyclists, ranging from
property-damage-only crashes
to those that result in
fatalities.
DBS................. Dynamic Brake Supplements the driver's
Support. application of the brake pedal
with additional braking when
sensors determine the driver-
applied braking is
insufficient to avoid an
imminent crash.
ESC................. Electronic Able to determine intended
Stability steering direction (steering
Control. wheel angle sensor), compare
it to the actual vehicle
direction, and then modulate
braking forces at each wheel
to induce a counter yaw when
the vehicle starts to lose
lateral stability.
FARS................ Fatality Analysis A nationwide census providing
Reporting System. annual data regarding fatal
injuries suffered in motor
vehicle crashes.

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FCW................. Forward Collision An auditory and visual warning
Warning. provided to the vehicle
operator by the AEB system
that is designed to induce an
immediate forward crash
avoidance response by the
vehicle operator.
FMCSR............... Federal Motor 49 CFR parts 350-399.
Carrier Safety
Regulations.
FMVSS............... Federal Motor ...............................
Vehicle Safety
Standards.
GES................. General Estimates Data from a nationally
System. representative sample of
police reported motor vehicle
crashes of all types, from
minor to fatal.
GVWR................ Gross Vehicle The value specified by the
Weight Rating. manufacturer as the maximum
design loaded weight of a
single vehicle.
BIL................. Bipartisan Public Law 117-58 (Nov. 15,
Infrastructure 2021).
Law.
MAIS................ Maximum A means of describing injury
Abbreviated severity based on an ordinal
Injury Scale. scale. An MAIS 1 injury is a
minor injury and an MAIS 5
injury is a critical injury.
MAP-21.............. The Moving Ahead A funding and authorization
for Progress in bill to govern United States
the 21st Century Federal surface transportation
Act. spending. It was enacted into
law on July 6, 2012.
NCAP................ New Car ...............................
Assessment
Program.
PDO................. Property-damage- A police-reported crash
only. involving a motor vehicle in
transport on a trafficway in
which no one involved in the
crash suffered any injuries.
PDOV................ Property-Damage- Damaged vehicles involved in
Only-Vehicles. property-damage-only crashes.
TTC................. Time to collision The theoretical time, given the
current speed of the vehicles,
after which a rear-end
collision with the lead
vehicle would occur if no
corrective action was taken.
VRTC................ Vehicle Research NHTSA's in-house laboratory.
and Test Center.
VTD................. Vehicle Test A test device used to test AEB
Device. system performance.
------------------------------------------------------------------------

I. Executive Summary

There were 38,824 people killed in motor vehicle crashes on U.S.
roadways in 2020 and early estimates put the number of fatalities at
42,915 for 2021.\1\ The Department established the National Roadway
Safety Strategy in January 2022 to address this rising number of
transportation deaths occurring on this country's streets, roads, and
highways.\2\ This NPRM takes a crucial step in implementing this
strategy by proposing to adopt a new Federal motor vehicle safety
standard (FMVSS) that would require heavy vehicles to have automatic
emergency braking (AEB) systems that mitigate the frequency and
severity of rear-end collisions with vehicles.
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\1\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813266, https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813283, https://www.nhtsa.gov/press-releases/early-estimate-2021-
traffic-
fatalities#:~:text=Preliminary%20data%20reported%20by%20the,from%201.
34%20fatalities%20in%202020.
\2\ https://www.transportation.gov/sites/dot.gov/files/2022-01/USDOT_National_Roadway_Safety_Strategy_0.pdf. Last accessed August
23, 2022.
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The crash problem addressed by heavy vehicle AEB is substantial, as
are the safety benefits to be gained. This NPRM addresses lead vehicle
rear-end, rollover, and loss of control crashes, and their associated
fatalities, injuries, and property damage. The NPRM also proposes new
Federal Motor Carrier Safety Regulations requiring the electronic
stability control and AEB systems to be on during vehicle operation.
Considering the effectiveness of AEB and electronic stability control
technology (ESC) at avoiding these crashes, the proposed rule would
conservatively prevent an estimated 19,118 crashes, save 155 lives, and
reduce 8,814 non-fatal injuries annually once all vehicles covered in
this rule are equipped with AEB and ESC. In addition, it would
eliminate 24,828 property-damage-only crashes annually.
In this NPRM, the term ``heavy vehicles'' refers to vehicles with a
gross vehicle weight rating (GVWR) greater than 4,536 kilograms (10,000
pounds). For application of the FMVSS, it is often necessary to further
categorize these heavy vehicles, as the FMVSS must be appropriate for
the particular type of motor vehicle for which they are
prescribed.^{3 4} Certain vehicles have common characteristics
relevant to the application of AEB, and categorizing those vehicles
accordingly allows for useful analyses, proposals, or other
considerations that are particularly appropriate for the vehicle group
and application of the safety standards.
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\3\ As required by 49 U.S.C 30111(b)(3), NHTSA shall consider
whether a proposed standard is reasonable, practicable, and
appropriate for the particular type of motor vehicle or motor
vehicle equipment for which it is prescribed.
\4\ This NPRM excludes heavy trailers because they typically do
not have braking components necessary for AEB.
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One useful way to categorize vehicles further is by GVWR. This NPRM
uses vehicle class numbers designed by NHTSA in 49 CFR 565, ``Vehicle
identification number requirements,'' and the Federal Highway
Administration that are based on GVWR.\5\ These class numbers, shown in
Table 2 below, are widely used by industry and States in categorizing
vehicles. In this NPRM, ``heavy vehicle'' and ``class 3 through 8''
both refer to all vehicles with a GVWR greater than 4,536 kg (10,000
lbs.). The term ``class 3 through 6'' refers to vehicles with a GVWR
greater than 4,536 kg (10,000 lbs.) and up to 11,793 kg (26,000 lbs.),
while the term ``class 7 to 8'' refers to vehicles with a GVWR greater
than 11,793 kg (26,000 lbs.).
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\5\ See https://ops.fhwa.dot.gov/publications/fhwahop10014/s5.htm#f21 (Last viewed on May 5, 2022).

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Table 2--Vehicle Class by GVWR
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Vehicle class GVWR
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1............................ Not greater than 2,722 kg (6,000 lbs.).
2a........................... Greater than 2,722 kg (6,000 lbs.) and up
to 3,856 kg (8,500 lbs.).
2b........................... Greater than 3,856 kg (8,500 lbs.) and up
to 4,536 kg (10,000 lbs.).
3............................ Greater than 4,536 kg (10,000 lbs.) and
up to 6,350 kg (14,000 lbs.).
4............................ Greater than 6,350 kg (14,000 lbs.) and
up to 7,257 kg (16,000 lbs.).
5............................ Greater than 7,257 kg (16,000 lbs.) and
up to 8,845 kg (19,500 lbs.).
6............................ Greater than 8,845 kg (19,500 lbs.) and
up to 11,793 kg (26,000 lbs.).
7............................ Greater than 11,793 kg (26,000 lbs.) and
up to 14,969 kg (33,000 lbs.).
8............................ Greater than 14,969 kg (33,000 lbs.).
------------------------------------------------------------------------

NHTSA and FMCSA have jointly developed this NPRM. Both agencies
will have complementary standards that respond to mandates in Section
23010 of the Bipartisan Infrastructure Law (BIL), as enacted as the
Infrastructure Investment and Jobs Act. Section 23010(b) requires the
Secretary to prescribe an FMVSS that requires any commercial motor
vehicle subject to FMVSS No. 136, ``Electronic stability control
systems for heavy vehicles,'' to be equipped with an AEB system meeting
performance requirements established in the new FMVSS not later than
two years after enactment. Section 23010(c) requires the Secretary to
prescribe a Federal Motor Carrier Safety Regulation (FMCSR) that
requires, for commercial motor vehicles subject to FMVSS No. 136, that
an AEB system installed pursuant to the new Federal motor vehicle
safety standard must be used at any time during which the commercial
motor vehicle is in operation. This NPRM sets forth NHTSA's proposed
FMVSS and FMCSA's proposed FMCSR issued pursuant to these provisions of
the BIL. In order to provide the benefits of AEB to a greater number of
vehicles, this proposal would also require that many heavy vehicles not
currently subject to FMVSS No. 136, including vehicles in classes 3
through 6, be equipped with ESC and AEB systems under the authority
provided in the Motor Vehicle Safety Act. Pursuant to section 23010(d)
of the BIL, NHTSA seeks public comment on this proposal.

NHTSA's Statutory Authority

NHTSA is proposing this NPRM under the National Traffic and Motor
Vehicle Safety Act (``Motor Vehicle Safety Act'') and in response to
the Bipartisan Infrastructure Law. Under 49 U.S.C. Chapter 301, Motor
Vehicle Safety (49 U.S.C. 30101 et seq.), the Secretary of
Transportation is responsible for prescribing motor vehicle safety
standards that are practicable, meet the need for motor vehicle safety,
and are stated in objective terms. ``Motor vehicle safety'' is defined
in the Motor Vehicle Safety Act as ``the performance of a motor vehicle
or motor vehicle equipment in a way that protects the public against
unreasonable risk of accidents occurring because of the design,
construction, or performance of a motor vehicle, and against
unreasonable risk of death or injury in a crash, and includes
nonoperational safety of a motor vehicle.'' ``Motor vehicle safety
standard'' means a minimum performance standard for motor vehicles or
motor vehicle equipment. When prescribing such standards, the Secretary
must consider all relevant, available motor vehicle safety information.
The Secretary must also consider whether a proposed standard is
reasonable, practicable, and appropriate for the types of motor
vehicles or motor vehicle equipment for which it is prescribed and the
extent to which the standard will further the statutory purpose of
reducing traffic accidents and associated deaths. The responsibility
for promulgation of Federal motor vehicle safety standards is delegated
to NHTSA.
In developing this NPRM, NHTSA carefully considered these statutory
requirements, and relevant Executive Orders, Departmental Orders, and
administrative laws and procedures. NHTSA is also issuing this NPRM in
response to the Bipartisan Infrastructure Law. Section 23010 of BIL \6\
requires the Secretary to prescribe a Federal motor vehicle safety
standard to require all commercial motor vehicles subject to a
particular brake system standard to be equipped with an AEB system
meeting established performance requirements. BIL directs the Secretary
to prescribe the standard not later than two years after the date of
enactment of the Act.
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\6\ Public Law 117-58, (Nov. 15, 2021).
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FMCSA's Statutory Authority

For purposes of this NPRM, FMCSA's authority is found in the Motor
Carrier Act of 1935 (1935 Act, 49 U.S.C. 31502) and the Motor Carrier
Safety Act of 1984 (1984 Act, 49 U.S.C. 31132 et seq.), both as
amended. The authorities assigned to the Secretary in these two acts
are delegated to the FMCSA Administrator in 49 CFR 1.87(i) and (f),
respectively. In addition, section 23010(c) of the BIL, Public Law 117-
58, 135 Stat. 429, 766-767, Nov. 15, 2021, requires FMCSA to adopt an
AEB regulation consistent with the companion NHTSA AEB regulation.
The 1935 Act authorizes the DOT to ``prescribe requirements for--
(1) qualifications and maximum hours of service of employees of and
safety of operation and equipment of a motor carrier; and (2)
qualifications and maximum hours of service of employees of, and
standards of equipment of, a motor private carrier, when needed to
promote safety of operations'' (49 U.S.C. 31502(b)). FMCSA's proposed
ESC and AEB regulations, which incorporate the ESC and AEB requirements
of the NHTSA rule, will require most motor carriers to maintain and use
the ESC and AEB systems required by the corresponding NHTSA regulations
to promote safety of operations.
The 1984 Act confers on DOT the authority to regulate drivers,
motor carriers, and vehicle equipment. ``At a minimum, the regulations
shall ensure that--(1) commercial motor vehicles are maintained,
equipped, loaded, and operated safely; (2) the responsibilities imposed
on operators of commercial motor vehicles do not impair their ability
to operate the vehicles safely; (3) the physical condition of operators
of commercial motor vehicles is adequate to enable them to operate the
vehicles safely; (4) the operation of commercial motor vehicles does
not have a deleterious effect on the physical condition of the
operators; and (5) an operator of a commercial motor vehicle is not
coerced by a motor carrier, shipper, receiver, or transportation
intermediary to operate a commercial motor vehicle in violation of a
regulation promulgated under this section, or chapter 51 or chapter 313
of this title'' (49 U.S.C. 31136(a)(1)-(5)).

[[Page 43178]]

FMCSA's proposed rule will help to ensure that commercial motor
vehicles (CMVs) equipped with the ESC and AEB systems mandated by NHTSA
are maintained and operated safely, as required by 49 U.S.C.
31136(a)(1). While the FMCSA proposal does not explicitly address the
remaining provisions of section 31136, it will enhance the ability of
drivers to operate safely, consistent with 49 U.S.C. 31136(a)(2)-(4).
Section 23010(c) of BIL requires FMCSA to prescribe a regulation
under 49 U.S.C. 31136 that requires that an automatic emergency braking
system installed in a commercial motor vehicle manufactured after the
effective date of the NHTSA standard that is in operation on or after
that date and is subject to 49 CFR 571.136 be used at any time during
which the commercial motor vehicle is in operation'' (135 Stat. 767).
Consistent with the BIL mandate, part of FMCSA's proposal would require
that motor carriers operating CMVs manufactured subject to FMVSS No.
136 maintain and use the required AEB devices as prescribed by NHTSA
whenever the CMV is operating.

AEB and ESC Systems

An AEB system employs multiple sensor technologies and sub-systems
that work together to sense when a vehicle is in a crash imminent
situation with a lead vehicle and, when necessary, automatically apply
the vehicle brakes if the driver has not done so, or apply the brakes
to supplement the driver's applied braking. Current systems use radar
and camera-based sensors or combinations thereof. AEB builds upon older
forward collision warning-only systems. An FCW-only system provides an
alert to a driver of an impending rear-end collision with a lead
vehicle to induce the driver to take action to avoid the crash but does
not automatically apply the brakes. This proposal would require both
FCW and AEB systems. For simplicity, when referring to AEB systems in
general, this proposal is referring to both FCW and AEB unless the
context suggests otherwise.
This proposal follows up on NHTSA's October 16, 2015 notice
granting a petition for rulemaking submitted by the Truck Safety
Coalition, the Center for Auto Safety, Advocates for Highway and Auto
Safety, and Road Safe America.\7\ The petitioners requested that NHTSA
establish a safety standard to require automatic forward collision
avoidance and mitigation systems on heavy vehicles. This rulemaking
also addresses recommendations made to NHTSA by the National
Transportation Safety Board.
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\7\ 80 FR 62487.
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The safety problem addressed by AEB is substantial. An annualized
average of 2017 to 2019 data from NHTSA's Fatality Analysis Reporting
System (FARS) and the Crash Report Sampling System (CRSS) shows that
heavy vehicles are involved in around 60,000 rear-end crashes in which
the heavy vehicle was the striking vehicle annually, which represents
11 percent of all crashes involving heavy vehicles.\8\ These rear-end
crashes resulted in 388 fatalities annually, which comprises 7.4
percent of all fatalities in heavy vehicle crashes. These crashes
resulted in approximately 30,000 injuries annually, or 14.4 percent of
all injuries in heavy vehicle crashes, and 84,000 damaged vehicles with
no injuries or fatalities.
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\8\ These rear-end crashes are cases where the heavy vehicle was
the striking vehicle.
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Considering vehicle size, approximately half of the rear-end
crashes, injuries, and fatalities resulting from rear-end crashes where
the heavy vehicle was the striking vehicle involved vehicles with a
gross vehicle weight rating above 4,536 kilograms (10,000 pounds) up to
11,793 kilograms (26,000 pounds). Similarly, half of all rear-end
crashes and the fatalities and injuries resulting from those crashes
where the heavy vehicle was the striking vehicle involved vehicles with
a gross vehicle weight rating of greater than 11.793 kilograms (26,000
pounds).
The speed of the striking vehicle is an important factor in the
severity of a crash. For example, in approximately 53 percent of
crashes, the striking vehicle was traveling at or under 30 mph (47 km/
h). Those crashes, though, were responsible for only approximately 1
percent of fatalities. In contrast, in approximately 17 percent of
crashes, the striking vehicle was traveling over 55 mph (89 km/h).
Those crashes resulted in 89 percent of the fatalities from rear-end
crashes involving heavy vehicles. While the majority of crashes occur
at low speeds, the overwhelming majority of fatalities result from
high-speed crashes. For AEB systems to address this safety problem,
they must function at both low and high speeds.
NHTSA has been studying AEB technologies since their conception
over 15 years ago. NHTSA and FMCSA have recognized the potential of
heavy vehicle AEB for many years and continued to research this
technology as it evolved from early generations to its current state.
As part of NHTSA's efforts to better understand these new collision
prevention technologies, NHTSA sponsored and conducted numerous
research projects, including ones focused on AEB and FCW for heavy
trucks. NHTSA conducted testing at its in-house testing facility, the
Vehicle Research and Test Center, to examine the effectiveness of AEB
in different crash scenarios and speeds. NHTSA and FMCSA have also
sponsored or conducted projects with a specific focus on the heavy
vehicle rear-end crash problem.
International standards for the regulation of AEB systems on heavy
vehicles exist and are under development. The European Union and Asian
countries have either already adopted or are considering AEB
regulations for heavy vehicles. More information can be found in
Appendix A of this document.
In 2016, NHTSA published its first report of track testing of heavy
vehicles equipped with AEB systems. NHTSA used its light vehicle test
procedures, similar to those used in NHTSA's New Car Assessment
Program,\9\ as a framework to adapt for use on heavy vehicles. These
scenarios included a stopped lead vehicle scenario, a slower moving
lead vehicle scenario, a decelerating lead vehicle scenario, and a
false positive scenario that consisted of driving over a steel trench
plate. NHTSA's initial testing of AEB systems focused on vehicles
equipped with ESC--primarily Class 8 truck tractors and motorcoaches.
Adjustments had to be made to the scenarios to account for the greater
stopping distances of heavy vehicles compared to light vehicles and to
the surrogate vehicle and towing device to ensure that the systems
performed as they would on the road. Testing of early heavy vehicle
systems indicated that vehicles did not automatically brake when
encountering a stopped lead vehicle. The false positive test also
resulted in FCW alerts, but no automatic braking.
---------------------------------------------------------------------------

\9\ NHTSA's New Car Assessment Program (NCAP) provides
comparative information on the safety performance of new vehicles to
assist consumers with vehicle purchasing decisions and to encourage
safety improvements.
---------------------------------------------------------------------------

Later testing was intended to evaluate the evolution of AEB
systems, to further refine the test procedures, and to test other
vehicle types such as single-unit trucks and class 3 through 6
vehicles. Newer FCW and AEB systems on heavy vehicles generally
performed better than older versions. Testing of these updated systems
exhibited less severe rear-end collisions through velocity reductions
before a collision or avoided contact with a lead vehicle entirely. The
refined test procedures addressed previous

[[Page 43179]]

issues with timing, range parameters, and the vehicle test device.
NHTSA's most recent testing of a 2021 Freightliner Cascadia, a
class 8 truck tractor, indicated that the AEB system was able to
prevent a collision with a lead vehicle at speeds between 40 km/h and
85 km/h. Collisions occurred with the lead vehicle at lower speeds,
although significant speed reductions were still achieved. This
suggests that collision avoidance at lower speed cannot necessarily be
extrapolated to performance outcomes at higher speed and may depend on
the specific ways AEB systems may be programmed. It also indicates that
AEB systems that prevent collisions at higher speeds are practicable.
NHTSA and FMCSA studies have also examined system availability
across all types of heavy vehicles. Across larger (class 7 and 8) air
braked truck tractors and motorcoaches, AEB systems are widely
available. A market analysis of class 3 through 6 heavy vehicles showed
that nearly all manufacturers had at least one vehicle model within
each class available with AEB. Two manufacturers had AEB advertised as
standard equipment on at least one model. All vehicles that were
offered with AEB systems were also equipped with ESC systems. A few
models that offered FCW-only systems (not capable of automatic brake
application) did so without also having ESC.
Based on these factors, and consistent with the Motor Vehicle
Safety Act and the BIL, NHTSA is proposing a new FMVSS that would
require nearly all heavy vehicles to be equipped with AEB systems.\10\
Furthermore, FMCSA is proposing that all commercial vehicles equipped
with ESC and AEB systems required by NHTSA's proposed rule be used any
time the commercial vehicle is in operation. NHTSA is further proposing
minimum performance criteria for AEB systems to meet the need for
safety. These performance criteria would ensure that AEB systems
function at a wide range of speeds that address the safety problem
associated with rear-end crashes, injuries, and fatalities.
---------------------------------------------------------------------------

\10\ The vehicles excluded from this proposal include trailers,
which by definition, are towed by other vehicles, and vehicles
already excluded from NHTSA's braking requirements. For details, see
section V.F.
---------------------------------------------------------------------------

Based on NHTSA's survey of publicly available data on ESC and AEB
system availability, all manufacturers that have equipped vehicles with
AEB systems (other than FCW-only systems) have done so only if the
vehicle is also equipped with an ESC system. Furthermore, NHTSA has
consulted with two AEB system manufacturers for heavy vehicles and both
indicated that they would equip vehicles with AEB only if they were
also equipped with ESC.\11\ An ESC system provides stability under
braking by using differential braking and engine torque reduction to
reduce lateral instability that could induce rollover or loss of
directional control. An ABS system also provides lateral stability
under braking. ABS systems are currently required on all vehicles
subject to this proposal under FMVSS Nos. 105 and 121. However, the
absence of any AEB systems available without ESC leads NHTSA to believe
that manufacturers have identified scenarios in which the operation of
an AEB system without ESC may have adverse safety effects that are not
adequately addressed by ABS systems alone.
---------------------------------------------------------------------------

\11\ On September 29, 2021, NHTSA met with Daimler Truck North
America (DTNA) and on October 22, 2021, NHTSA met with Bendix to
discuss the AEB systems of heavy vehicles.
---------------------------------------------------------------------------

Summary of the Proposal

NHTSA has tentatively concluded based upon this information that a
safety need exists for an ESC system to be installed on a vehicle
equipped with AEB. Consequently, this proposal also requires nearly all
heavy vehicles to be equipped with an ESC system.\12\ Even separate
from the benefits of AEB, the safety problem related to the vehicles
addressed by the FMVSS No. 136 amendments is also substantial. Class 3
through 6 heavy vehicles are involved in approximately 17,000 rollover
and loss of control crashes annually. These crashes resulted in 178
fatalities annually, approximately 4,000 non-fatal injuries, and 13,000
damaged vehicles. Currently, pursuant to FMVSS No. 136, only class 7
and 8 truck tractors and certain large buses are required to have ESC
systems. FMVSS No. 136 includes both vehicle equipment requirements and
performance requirements. This proposal would amend FMVSS No. 136 to
require nearly all heavy vehicles to have an ESC system that meets the
equipment requirements, the general system operational capability
requirements, and malfunction detection requirements of FMVSS No. 136.
It would not, as proposed, require vehicles not currently required to
have ESC systems to meet any test track performance requirements for
ESC systems, though the agency does request comment on whether to
include a performance test and, if so, what that test should be. In
designing any potential test, NHTSA wishes to remain conscious of the
potential testing burden on small businesses and the multi-stage
vehicle manufacturers.
---------------------------------------------------------------------------

\12\ The vehicles excluded from the proposed ESC requirements
are the same vehicles excluded from the proposed AEB requirements.
---------------------------------------------------------------------------

The proposed standard includes certain requirements for AEB
systems. First, vehicles would be required to provide the driver with a
forward collision warning at any forward speed greater than 10 km/h
(6.2 mph). NHTSA is proposing that the forward collision warning be
auditory and visual with limited specifications for each of the warning
modalities. NHTSA has tentatively concluded that no further
specification of the warning is necessary.
Second, vehicles would be required to have an AEB system that
applies the service brakes automatically at any forward speed greater
than 10 km/h (6.2 mph) when a collision with a lead vehicle is
imminent. This requirement serves to ensure that AEB systems operate at
all speeds above 10 km/h, even if they are above the speeds tested by
NHTSA. This requirement also assures at least some level of AEB system
performance in rear-end crashes other than those for which NHTSA has
test procedures.
Third, the AEB system would be required to prevent the vehicle from
colliding with a lead vehicle when tested according to the proposed
standard's test procedures. Vehicles with AEB systems meeting the
proposed standard would have to automatically activate the braking
system when they encounter a stopped lead vehicle, a slower moving lead
vehicle, or a decelerating lead vehicle.
The proposed requirements also include two tests to ensure that the
AEB system does not inappropriately activate when no collision is
actually imminent. These false positive tests provide some assurance
that an AEB system is capable of differentiating between an actual
imminent collision and a non-threat. While these tests are not
comprehensive, they establish a minimum performance for non-activation
of AEB systems. The two scenarios NHTSA proposes to test are driving
over a steel trench plate and driving between two parked vehicles.
The final proposed requirement for AEB systems is that they be
capable of detecting a system malfunction and notify the driver of any
malfunction that causes the AEB system not to operate. This proposed
requirement would include any malfunction solely attributable to sensor
obstruction, such as by accumulated snow or debris, dense fog, or
sunlight glare. The malfunction telltale must remain active as long as
the malfunction exists, and

[[Page 43180]]

the vehicle's starting system is on. The proposal does not include any
specifications for the form of this notification to the driver.
The NPRM also includes proposed test procedures. In this NPRM, the
heavy vehicle being evaluated with AEB is referred to as the ``subject
vehicle.'' Other vehicles involved in the test are referred to as
``vehicle test devices,'' (VTDs) and a specific type of VTD called the
``lead vehicle'' refers to a vehicle which is ahead in the same lane,
in the path of the moving subject vehicle. To ensure repeatable test
conduct that reflects how a subject vehicle might respond in the real
world, this proposal includes broad specifications for a vehicle test
device to be used as a lead vehicle or principal other vehicle during
testing. NHTSA is proposing that the vehicle test device is based on
the specifications in the International Organization for
Standardization (ISO) standard 19206-3:2021.\13\ The vehicle test
device is a tool that NHTSA would use in the agency's compliance tests
to measure the performance of automatic emergency braking systems
required by the FMVSS. For its research testing, NHTSA has been using a
full-size surrogate vehicle, the Global Vehicle Target (GVT). The GVT
falls within the specifications of ISO 19206-3:2021. These
specifications include specifications for the dimensions, color and
reflectivity, and the radar cross section of a vehicle test device that
ensure it appears like a real vehicle to vehicle sensors.
---------------------------------------------------------------------------

\13\ ISO 19206-3:2021, ``Road vehicles--Test devices for target
vehicles, vulnerable road users and other objects, for assessment of
active safety functions--Part 3: Requirements for passenger vehicle
3D targets.'' https://www.iso.org/standard/70133.html. May 2021.
---------------------------------------------------------------------------

NHTSA has included three test scenarios in this proposed rule for
AEB when approaching a lead vehicle--a stopped lead vehicle, a slower
moving lead vehicle, and a decelerating lead vehicle. The stopped lead
vehicle scenario consists of the subject vehicle--that is, the vehicle
being tested--traveling straight at a constant speed approaching a
stopped lead vehicle in the center of its path. To satisfy the proposed
performance requirement, the subject vehicle must provide an FCW and
stop prior to colliding with the lead vehicle. NHTSA proposes to
conduct this scenario both with no manual brake application and with
manual brake application. Testing with manual brake application is
similar to the DBS test procedure that is included in New Car
Assessment Program for light vehicles. While DBS is not generally
advertised as a feature of AEB systems on air braked vehicles, driver-
applied braking should not suppress automatic braking. Testing without
manual brake application would be conducted at any constant speed
between 10 km/h and 80 km/h. The 80 km/h upper bound of testing
reflects safety limitations that would result from any collision
resulting from a failure of an AEB system to activate in the testing
environment. However, with manual brake application, NHTSA proposes to
test vehicles up to 100 km/h. This is possible because the manual brake
application ensures at least some level of speed reduction even in a
test failure where automatic braking does not occur.
The second test scenario is a slower moving lead vehicle. In this
scenario, the subject vehicle is traveling straight at a constant
speed, approaching a lead vehicle traveling at a slower speed in the
subject vehicle's path. To satisfy the proposed performance test
requirement, the subject vehicle must provide an FCW and slow to a
speed equal to or below the lead vehicle's speed without colliding with
the lead vehicle. As with the stopped lead vehicle test, NHTSA proposes
to perform this test with both no manual brake application and manual
brake application. The subject vehicle speed without manual brake
application would be any constant speed between 40 km/h and 80 km/h,
and with manual brake application, testing would be conducted at any
constant speed between 70 km/h and 100 km/h. The lead vehicle would
travel at 20 km/h in all tests.
The third test scenario is a decelerating lead vehicle. In this
scenario, the subject vehicle and lead vehicle are travelling at the
same constant speed in the same path and the lead vehicle begins to
decelerate. To satisfy the proposed performance test requirement, the
subject vehicle must provide an FCW and stop without colliding with the
lead vehicle. As with the other AEB tests approaching a lead vehicle,
this test is performed both with and without manual brake application.
However, the test speeds are the same for both scenarios--either 50 km/
h or 80 km/h. The lead vehicle would decelerate with a magnitude
between 0.3g and 0.4g and the headway between the vehicles would be any
distance between 21 m and 40 m (for 50 km/h tests) or 28 m and 40 m
(for 80 km/h tests). The upper bound of the lead vehicle deceleration
and the lower bound of the headway were chosen to ensure that the
corresponding test scenarios would not require a brake performance
beyond what is necessary to satisfy the minimum stopping distance
requirements in the FMVSS applicable to brake performance.
This proposal would require that all of the NHTSA AEB requirements
be phased in within four years of publication of a final rule. Truck
tractors and certain large buses with a GVWR of greater than 11,793
kilograms (26,000 pounds) that are currently subject to FMVSS No. 136
would be required to meet all requirements within three years. Vehicles
not currently subject to FMVSS No. 136 would be required to have ESC
and AEB systems within four years of publication of a final rule.
Small-volume manufacturers, final-stage manufacturers, and alterers
would be allowed one additional year (five years total) of lead time.
Consistent with the BIL mandate, FMCSA proposes to require that
motor carriers operating CMVs manufactured subject to FMVSS No. 136,
maintain and use the required AEB and ESC systems as prescribed by
NHTSA for the effective life of the CMV. FMCSA's proposed rule is
intended to ensure that commercial motor vehicles equipped with the ESC
and AEB systems mandated by NHTSA are maintained and operated safely,
as required by 49 U.S.C. 31136(a)(1). While the FMCSA proposal does not
explicitly address the remaining provisions of section 31136, it will
enhance the ability of drivers to operate safely, consistent with 49
U.S.C. 31136(a)(2)-(4). FMCSA's proposal would require the ESC and AEB
systems to be inspected and maintained in accordance with 49 CFR part
396, Inspection, Repair, and Maintenance (Sec. 396.3).
The proposed requirements would ensure that the benefits resulting
from CMVs equipped with ESC and AEB systems are sustained through
proper maintenance and operation. The maintenance costs include annual
costs required to keep the ESC and AEB systems operative. FMCSA
believes the cost of maintaining the ESC and AEB systems over their
lifetimes is minimal compared to the cost of equipping trucks with ESC
and AEB systems and may be covered by regular annual maintenance.
NHTSA and FMCSA have jointly determined not to propose retrofitting
requirements AEB for existing heavy vehicles and ESC for vehicles not
currently subject to FMVSS No. 136. For technical reasons, AEB and ESC
retrofits are difficult to apply broadly, generically, or inexpensively
and thus this NPRM does not propose a retrofit requirement.
NHTSA and FMCSA seek comments and suggestions on any aspect of this

[[Page 43181]]

proposal and any alternative requirements to address this safety
problem. NHTSA and FMCSA also request comments on the proposed lead
time for meeting these requirements, and how the lead time can be
structured to maximize the benefits that can be realized most quickly
while ensuring that the standard is practicable. Finally, NHTSA and
FMCSA seek comment on whether and how this proposal may
disproportionately impact small businesses and how NHTSA and FMCSA
could revise this proposal to minimize any disproportionate impact.

Benefits and Costs

NHTSA and FMCSA have issued a Preliminary Regulatory Impact
Analysis (PRIA) that analyzes the potential impacts of this proposed
rule. The PRIA is available in the docket for this NPRM.\14\ This
proposed rule is expected to substantially decrease risks associated
with rear-end, rollover, and loss of control crashes. The effectiveness
of AEB and ESC at avoiding rear-end, rollover, and loss of control
crashes is summarized in Table 3 for AEB and Table 4 for ESC.
---------------------------------------------------------------------------

\14\ The PRIA may be obtained by downloading it or by contacting
Docket Management at the address or telephone number provided at the
beginning of this document.

Table 3--AEB Effectiveness (%) by Vehicle Class Range and Crash Scenario
----------------------------------------------------------------------------------------------------------------
Stopped lead Slower-moving lead Decelerating lead
Vehicle class range vehicle vehicle vehicle
----------------------------------------------------------------------------------------------------------------
7-8................................................. 38.5 49.2 49.2
3-6................................................. 43.0 47.8 47.8
----------------------------------------------------------------------------------------------------------------

Table 4--ESC Effectiveness (%) by Crash Scenario
------------------------------------------------------------------------
Vehicle class range Rollover Loss of control
------------------------------------------------------------------------
3-6........................... 48.0 14.0
------------------------------------------------------------------------

Considering the annual rear-end, rollover, and loss of control
crashes, as well as the effectiveness of AEB and ESC at avoiding these
crashes, the proposed rule would prevent an estimated 19,118 crashes,
save 155 lives, and reduce 8,814 non-fatal injuries, annually. In
addition, the proposed rule would eliminate an estimated 24,828
property-damage-only-vehicles (PDOVs), annually. Table 5 shows these
estimated benefits also by vehicle class and technology.

Table 5--Estimated Annual Benefits of the Proposed Rule
----------------------------------------------------------------------------------------------------------------
Non-fatal
Crashes Fatalities injuries PDOVs avoided
avoided avoided avoided
----------------------------------------------------------------------------------------------------------------
By Vehicle Class
----------------------------------------------------------------------------------------------------------------
Class 7-8....................................... 5,691 40 2,822 7,958
Class 3-6....................................... 13,427 115 5,992 16,870
---------------------------------------------------------------
Total....................................... 19,118 155 8,814 24,828
----------------------------------------------------------------------------------------------------------------
By Technology
----------------------------------------------------------------------------------------------------------------
AEB............................................. 16,224 106 8,058 22,713
ESC............................................. 2,894 49 756 2,115
---------------------------------------------------------------
Total....................................... 19,118 155 8,814 24,828
----------------------------------------------------------------------------------------------------------------

There are two potential unintended consequences that cannot be
quantified: the impact of false activations on safety and the potential
impact of sensor degradation over time on AEB performance. However, the
required malfunction indicator combined with FMCSA's proposed AEB and
ESC inspection and maintenance requirements would help vehicle
operators maintain AEB systems and substantially reduce degradation of
AEB sensor performance. We seek comments on these two issues and ask
for any data that can help us to quantify these impacts.
The benefits estimate includes assumptions that likely result in
the underestimation of the benefits of this proposal because it does
not quantify the benefits from crash mitigation. That is, the benefits
only reflect those resulting from crashes that are avoided as a result
of AEB and ESC. It is likely that AEB will also reduce the severity of
crashes that are not prevented. Some of these crashes mitigated may
include fatalities and significant injuries that will be prevented or
mitigated by AEB. Finally, this NPRM does not quantify any potential
benefits that AEB could provide during adverse environmental conditions
(night, wet, etc.). While AEB is likely to be effective in many of
these crashes, NHTSA is not aware of any data to quantify the
performance degradation of AEB in adverse conditions.
The benefits of this proposed rule, monetized and analyzed with the
total annual cost, are summarized in Table 6. The total annual cost,
considering the implementation of both AEB and ESC technologies
proposed in this rule, is

[[Page 43182]]

estimated to be $353 million. The proposed rule would generate a net
benefit of $2.58 to $1.81 billion, annually under 3 and 7 percent
discount rates. The proposed rule would be cost-effective given that
the highest estimated net cost per fatal equivalent would be $0.50
million. Maintenance costs are considered de minimis and therefore not
included in the cost estimate.

Table 6--Estimated Annual Cost, Monetized Benefits, Cost-Effectiveness, and Net Benefits of the Proposed Rule
[2021 Dollars in millions]
----------------------------------------------------------------------------------------------------------------
Monetized Net cost per
Discount rates Annual cost * benefits fatal equivalent Net benefits
----------------------------------------------------------------------------------------------------------------
3 Percent.................................... $353.3 $2,937.0 \15\ -$0.12 $2,583.7
7 Percent.................................... 353.3 2,158.0 0.50 1,807.1
----------------------------------------------------------------------------------------------------------------
* Paid at purchasing; no need to discount.

NHTSA has issued an NPRM that proposes to adopt an FMVSS for AEB
requirements for light vehicles, including pedestrian AEB. \16\ NHTSA
notes that it may decide to issue final rules adopting the AEB
requirements for light and heavy vehicles in a way that incorporates
the AEB requirements into a single Federal motor vehicle safety
standard for all vehicle classes.
---------------------------------------------------------------------------

\15\ The negative net cost per fatal equivalent reflects the
fact that savings from reducing traffic congestion and damaged
property is greater the total compliance costs of the proposed rule.
\16\ 88 FR 38632 (June 13, 2023).
---------------------------------------------------------------------------

The following is a brief explanation of terms and technologies used
to describe AEB systems. More detailed information can be found in
Appendix A to this preamble.

Radar-Based Sensors

Heavy vehicle AEB systems typically employ radar sensors. At its
simplest, radar is a time-of-flight sensor that measures the time
between when a radio wave is transmitted and its reflection is
recorded. This time-of-flight is then used to calculate how far away
the object is that caused the reflection. Information about the
reflecting object, such as the speed at which it is travelling, can
also be determined. Radar units are compact, relatively easy to mount,
and do not require a line of sight to function properly. Radar can
penetrate most rubbers and plastics, allowing for the units to be
installed behind grilles and bumper fascia, increasing mounting
options. Radar can detect objects in low-light situations and also
works well in environmental conditions like precipitation and fog.

Camera Sensors

Cameras are passive sensors in which optical data are recorded then
processed to allow for object detection and classification. Cameras are
an important part of many automotive AEB systems, and one or more
cameras are typically mounted behind the front windshield and often up
high near the rearview mirror. Cameras at this location provide a good
view of the road and are protected by the windshield from debris,
grease, dirt, and other contaminants that can cover the sensor. Systems
that utilize two or more cameras can see stereoscopically, allowing the
processing system to determine range information along with detection
and classification.

Electronically Modulated Braking Systems

Automatic actuation of the vehicle brakes requires more than just
systems to sense when a collision is imminent. In addition to the
sensing system, hardware is needed to physically apply the brakes
without relying on the driver to apply the brake pedal. AEB leverages
two foundational braking technologies, antilock braking systems (ABS)
and electronic stability control. AEB uses the hardware equipped for
ESC and electronically applies the brakes to avoid certain scenarios
where a crash with a vehicle is imminent.
ABS: Antilock braking systems automatically control the degree of
longitudinal wheel slip during braking to prevent wheel lock and
minimize skidding by sensing the rate of angular rotation of the wheels
and modulating the braking force at the wheels to keep the wheels from
locking. Preventing wheel lock, and therefore skidding, greatly
increases the controllability of the vehicle during a panic stop.
Modern ABS systems have wheel speed sensors, independent brake
modulation at each wheel, and can increase or decrease braking
pressures as needed. During modulation of a brake application, the ABS
system repeatedly relieves and regenerates pressure to quickly release
and reapply, or ``pulse,'' the brake.
ESC: ESC builds upon the antilock brakes system by adding two
sensors, a steering wheel angle sensor and an inertial measurement
unit. These sensors allow the ESC controller to determine intended
steering direction (steering wheel angle sensor), compare it to the
actual vehicle direction, and then modulate braking forces at each
wheel to induce a corrective yaw moment when the vehicle starts to lose
lateral stability. An ESC system can control the brakes even when the
vehicle operator is not pressing the brake pedal.
When an AEB system activates in response to an imminent collision,
much of the same or similar hardware from ESC systems is used to
automatically control and modulate the brakes. Like ESC, an AEB system
includes components that give the vehicle the capacity to automatically
apply the brakes even when the vehicle operator is not pressing the
brake pedal. To do this in hydraulic brake systems, hydraulic brake
pressure is generated by a pump similarly as with ABS. In a pneumatic
brake system, the air pressure is already available via the air
reservoir and air compressor, and the ESC system must direct this
pressure accordingly. Additionally, the safety benefits of ESC enable
an AEB system to operate at its potential. Especially under the high-
speed, heavy-deceleration emergency braking events that potentially
occur during AEB activation, ESC could improve vehicle stability and
reduce the propensity for loss of control or rollover crashes that may
result from a steering response to an impending rear-end collision.

Forward Collision Warning

A forward collision warning (FCW) system uses the camera and radar
sensors described above, and couples them with an alert mechanism. An
FCW system can monitor a vehicle's speed, the speed of the vehicle in
front of it, and the distance between the two vehicles. If the FCW
system determines that the distance from the driver's vehicle to the
vehicle in front of it is too short, and the closing velocity between

[[Page 43183]]

the two vehicles too high, the system warns the driver of an impending
rear-end collision. Warning systems in use today provide drivers with a
visual display, such as a light on the instrument panel, an auditory
signal (e.g., beeping tone or chime), and/or a haptic signal that
provides tactile feedback to the driver (e.g., rapid vibrations of the
seat pan or steering wheel or a momentary brake pulse) to alert the
driver of an impending crash so they may manually intervene. The alerts
provided by FCW systems, even those that include momentary brake
pulses, are not intended to provide significant and sustained vehicle
deceleration. Rather, the FCW system is intended to inform the driver
that they must take corrective action in certain rear-end crash-
imminent driving situations.

Automatic Emergency Braking

An automatic emergency braking system automatically applies the
brakes to help drivers avoid or mitigate the severity of rear-end
crashes. AEB has two primary functions, crash imminent braking (CIB)
and a brake support system that supplements a driver's applied braking,
which is referred to as dynamic brake support (DBS) in the light
vehicle context. CIB systems apply automatic braking when forward-
looking sensors indicate a crash is imminent and the driver has not
applied the brakes, while supplemental brake support systems use the
same forward-looking sensors, but also supplement the driver's
application of the brake pedal with enhanced braking when sensors
determine the driver-applied braking is insufficient to avoid the
imminent crash. This NPRM does not split the terminology of these CIB
and supplemental brake support functionalities, and instead considers
both functions as part of AEB. The proposed standard includes
performance tests that would entail installation of AEB that has both
CIB and supplemental brake support functionalities.

``AEB'' as Used in This NPRM

As used in this NPRM, when we refer to ``AEB,'' we mean a system
that has: (a) a forward collision warning (FCW) component to alert the
driver to an impending collision; (b) a crash imminent braking
component (CIB) that automatically applies the vehicle's brakes if the
driver does not respond to an imminent crash in the forward direction
regardless of whether there's an FCW alert; and, (c) a supplemental
brake support component that automatically supplements the driver's
brake application if the driver applies insufficient manual braking.

II. Safety Problem

Overview

There were 38,824 people killed in motor vehicle crashes on U.S.
roadways in 2020 and 42,939 in 2021.^{17 18} The 2021 data are
the highest numbers of fatalities since 2005. While the upward trend in
fatalities may be related to increases in risky driving behaviors
during the COVID-19 pandemic,\19\ NHTSA data from 2010 to 2019 show an
increase of approximately 3,000 fatalities since 2010. There has also
been an upward trend since 2010 in the total number of motor vehicle
crashes, which corresponds to an increase in fatalities, injuries, and
property damage. NHTSA uses data from its FARS and the CRSS, to account
for and understand motor vehicle crashes.\20\
---------------------------------------------------------------------------

\17\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813266;, https://www.nhtsa.gov/press-releases/early-
estimate-2021-traffic-
fatalities#:~:text=Preliminary%20data%20reported%20by%20the,from%201.
34%20fatalities%20in%202020.
\18\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813435; https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813283; https://www.nhtsa.gov/press-releases/early-
estimate-2021-traffic-
fatalities#:~:text=Preliminary%20data%20reported%20by%20the,from%201.
34%20fatalities%20in%202020.
\19\ These behaviors relate to increases in impaired driving,
the non-use of seat belts, and speeding.
\20\ The Crash Report Sampling System (CRSS) builds on a
previous, long-running National Automotive Sampling System General
Estimates System (NASS GES). CRSS is a sample of police-reported
crashes involving all types of motor vehicles, pedestrians, and
cyclists, ranging from property-damage-only crashes to those that
result in fatalities. CRSS is used to estimate the overall crash
picture, identify highway safety problem areas, measure trends,
drive consumer information initiatives, and form the basis for cost
and benefit analyses of highway safety initiatives and regulations.
FARS contains data on every fatal motor vehicle traffic crash within
the 50 States, the District of Columbia, and Puerto Rico. To be
included in FARS, a traffic crash must involve a motor vehicle
traveling on a public trafficway that results in the death of a
vehicle occupant or a nonoccupant within 30 days of the crash.
---------------------------------------------------------------------------

Rear-End Crashes

As defined in a NHTSA technical manual relating to data entry for
FARS and CRSS, rear-end crashes are incidents where the first event is
defined as the frontal area of one vehicle striking a vehicle ahead in
the same travel lane. In a rear-end crash, as instructed by the FARS/
CRSS Coding and Validation Manual, the vehicle ahead is categorized as
intending to head either straight, left or right, and is either
stopped, travelling at a lower speed, or decelerating.\21\
---------------------------------------------------------------------------

\21\ https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813251 Category II Configuration D. Rear-End.
---------------------------------------------------------------------------

Heavy Vehicle Rear-End Crashes

On average from 2017 to 2019, there were 6.65 million annual
police-reported crashes resulting in 36,888 fatalities. Of the police-
reported crashes, approximately 550,000 involved a heavy vehicle (a
vehicle with a GVWR greater than 4,536 kg (10,000 pounds)), resulting
in 5,255 fatalities.\22\ Thus, heavy vehicle crashes represented 8.3
percent of the total number of crashes and resulted in 14.2 percent of
all fatalities. Annually, the entire U.S. fleet traveled a total of
3,237,449 million miles, and 9.3 percent of total vehicle miles
traveled were in heavy vehicles.\23\
---------------------------------------------------------------------------

\22\ Data are from 2017-2019 FARS and CRSS crash databases, as
discussed in the accompanying PRIA.
\23\ See the Traffic Safety Report at https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813141 (Last
viewed September 22, 2022).
---------------------------------------------------------------------------

A typical heavy vehicle rear-end crash is characterized by a heavy
vehicle travelling on a roadway and colliding with another vehicle
ahead of it travelling in the same direction, but which is stopped,
moving slower, or decelerating, usually within the same lane. While
these crashes occur nationwide on all types of roads and in all
environments, they overwhelmingly take place on straight roadways (99
percent) and in dry conditions (85 percent). Approximately 60,000 (11
percent of heavy vehicle crashes annually), were rear-end crashes in
which the heavy vehicle was the striking vehicle. These rear-end
crashes resulted in 388 fatalities annually (7.4 percent of all
fatalities in heavy vehicle crashes), approximately 30,000 injuries
(14.3 percent of injuries in all heavy vehicle crashes.), and
approximately 84,000 damaged vehicles (without injuries or
fatalities).\24\
---------------------------------------------------------------------------

\24\ All data in this paragraph are from 2017-2019 FARS and CRSS
crash databases, and are discussed in the accompanying PRIA.
---------------------------------------------------------------------------

The PRIA accompanying this proposal includes a complete review and
analysis of the relevant crash data and provides full details about the
target population of this NPRM. A summary of the PRIA is contained in
section XI. of this proposal.

Rear-End Crashes by Heavy Vehicle Class

Installing AEB on vehicles is related to the installation of ESC on
vehicles. ESC is required by FMVSS No. 136 for truck tractors and
certain large buses with a GVWR greater than 11,793 kg

[[Page 43184]]

(26,000 lbs.). Although the group of heavy vehicles that is not subject
to FMVSS No. 136 and the group of heavy vehicles that is subject to
FMVSS No. 136 are not solely defined by GVWR range, those not subject
to FMVSS No. 136 can be generally characterized as class 3-6 vehicles,
while those that are subject to FMVSS No. 136 can be generally
characterized as class 7-8 vehicles. Accordingly, NHTSA has further
examined rear-end crash data for each of these vehicle class ranges.
The lower weight range of class 3 through 6 includes vehicles such
as delivery vans, utility trucks, and smaller buses. Sales data for
2018 and 2019 show that on average 454,692 class 3-6 vehicles per year
were sold in the U.S.\25\ Approximately 57 percent of these were class
3 vehicles. Based on crash data, NHTSA determined that class 3-6
vehicles are involved in an annual average of 29,493 rear-end crashes
where the heavy vehicle is the striking vehicle. As a result of these
crashes, there were 184 fatalities, 14,675 injuries, and 41,285 PDOVs
per year on average. A NHTSA study also shows that, according to FARS
data, fatalities related to crashes involving these vehicles are on the
rise.\26\ In 2015, trucks and buses in this category were involved in 2
percent of all fatal crashes in the U.S., but that increased to 4
percent in 2019.\27\
---------------------------------------------------------------------------

\25\ This information is available in the S&P Global's
presentation titled ``MHCV Safety Technology Study,'' which has been
placed in the docket identified in the heading of this NPRM.
\26\ Mynatt, M., Zhang, F., Brophy, J., Subramanian, R., Morgan,
T. (2022, September). Medium Truck Special Study (Report No. DOT HS
813 371). Washington, DC: National Highway Traffic Safety
Administration.
\27\ In 2015, 655 of the 32,538 total fatalities involved a
class 3-6 truck. In 2019, it increased to 1,301 of the 33,244 total
fatalities.
---------------------------------------------------------------------------

The higher weight range of class 7 and 8 includes vehicles such as
larger single-unit trucks, combination tractor-trailers, transit buses,
and motorcoaches (GVWR greater than 11,793 kg (26,000 lbs.)).\28\ Sales
data for 2018 and 2019 shows that on average 332,558 class 7-8 vehicles
per year were sold in the U.S. Approximately 77 percent of these were
class 8 vehicles. NHTSA estimates that class 7 and 8 vehicles are
involved in 30,416 rear-end crashes where the heavy vehicle is the
striking vehicle. As a result of these crashes, there were an annual
average of 204 fatalities, 15,117 injuries, and 42,466 PDOVs. As these
data indicate, the numbers of crashes, fatalities, injuries, and PDOVs
are very similar for both class 3-6 and class 7-8.
---------------------------------------------------------------------------

\28\ These vehicles are subject to FMVSS No. 136 and so must
have ESC.
---------------------------------------------------------------------------

Rear-End Crashes by Vehicle Travel Speed and Roadway Speed Limit

Pre-crash vehicle travel speed is highly important in understanding
the heavy vehicle rear-end crash problem and is perhaps the most
influential factor in outcome of these crashes. In NHTSA's analysis of
the data, travel speed of the striking vehicle was markedly different
when comparing non-fatal and fatal rear-end truck crashes. As shown in
Figure 1, the percentage of heavy vehicle rear-end crashes with a
fatality is greatest at higher travel speeds.\29\ Approximately 89
percent of fatal heavy vehicle rear-end crashes occur at above 80 km/h
(50 mph). For non-fatal heavy vehicle rear-end crashes, the trend is
more or less reversed, with approximately 83 percent of these crashes
occurring at travel speeds below 80 km/h (50 mph). These data
illustrate the distribution of a crash problem across all travel
speeds.
---------------------------------------------------------------------------

\29\ Note that the figure shows percentage of the total number
of fatal or non-fatal crashes. The total number of crashes is much
greater for non-fatal crashes.
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BILLING CODE 4910-59-P

[[Page 43185]]

[GRAPHIC] [TIFF OMITTED] TP06JY23.001

The speed limits in heavy vehicle rear-end crashes also show a
similar trend. NHTSA categorized the fatal and non-fatal crash data
according to posted speed limit at the crash location, as illustrated
in Figure 2.\31\ These data show that over 90 percent of heavy vehicle
rear-end crashes with a fatality occur on roadways with a posted speed
limit higher than 50 mph (80 km/h). This reinforces the association
between higher speeds and fatal crash outcome in these types of
crashes. In contrast, non-fatal rear-end crashes tend to occur most
commonly on roads with lower speed limit, with a peak frequency at
speed limits of 45 mph (72 km/h). These data help in understanding the
conditions under which heavy vehicle rear-end crashes of different
severities occur.
---------------------------------------------------------------------------

\30\ Data are from 2017-2019 FARS and CRSS crash databases, as
discussed in the PRIA section on target population.
\31\ These data naturally are clustered around 5 mph intervals
normally assigned for posted speed limits on roadways.

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[[Page 43186]]

[GRAPHIC] [TIFF OMITTED] TP06JY23.002

BILLING CODE 4910-59-C

Safety Problem That Can Be Addressed by AEB

NHTSA identified the set of crashes that might be prevented by AEB
systems equipped on heavy vehicles. To determine these crashes for this
NPRM, NHTSA analyzed 2017 through 2019 crash data for heavy vehicles.
The 2017 through 2019 years were chosen because they provide the most
recent available data, and thus reflect newer model year vehicles,
safety technologies, and crash environments.\33\ The crash-related
statistics discussed in this section, often depicted as annual
averages, are derived from these data.
---------------------------------------------------------------------------

\32\ Data are from 2017-2019 FARS and CRSS crash databases, as
discussed in the PRIA section on target population.
\33\ Crash data from 2020, although available, were excluded due
to a significant reduction in weighted cases for CRSS. The 2020 data
was greatly influenced by COVID-19 and might not reflect the long-
term trend of crash outcomes, as described in the accompanying PRIA.
---------------------------------------------------------------------------

To develop a target crash population relevant to AEB, the agency
identified crashes that were classified as rear-end crashes as
instructed by the FARS/CRSS manual and in which the striking vehicle
was a heavy vehicle. NHTSA analyzed rear-end crashes in which the
vehicle ahead is categorized as being either stopped, travelling at a
lower speed, or decelerating, and also examined a few other categories
to account for rear-end crashes that did not fit into the three
categories. Additionally, NHTSA included some other cases which,
although not classified as rear-end, were multi-vehicle crashes that
still involved the front end of a heavy vehicle colliding with the
rear-end of another vehicle.
NHTSA believes that AEB will help reduce the severity of rear-end
crashes occurring in a wide variety of real-world situations. However,
the data analysis presented some rear-end crash cases where, due to a
significant sequence of events or other conditions preceding the crash,
the agency had less certainty of the extent to which AEB systems would
be able to reduce the crash severity. For example, if the data
indicated that the heavy vehicle had changed lanes just prior to
colliding with a vehicle ahead, there would potentially not have been
sufficient time and/or space for the AEB system to properly identify
and track that vehicle and brake in time to avoid the crash. As another
example, if the road surface conditions were icy and slippery, the AEB
system may have been less likely to prevent a crash due to the reduced
friction and increased stopping distances. In another example, if the
struck vehicle was a motorcycle, NHTSA is uncertain of the AEB system's
capacity to perform optimally since motorcycles may be more difficult
to detect.\34\
---------------------------------------------------------------------------

\34\ NHTSA is currently conducting research tests to understand
AEB performance in light vehicle rear-end crashes with motorcycles.
Two types of AEB sensor types (e.g., camera and camera+radar) were
investigated. See www.regulations.gov, Docket No. NHTSA-2022-0091. A
study by the RDW, the vehicle authority in the Netherlands,
indicated that adaptive cruise control systems (which detect a
vehicle ahead, similar to AEB) had more difficulty detecting
motorcycles. https://www.femamotorcycling.eu/wp-content/uploads/Final%20Report_motorcycle_ADAS_RDW.pdf (last accessed February 10,
2023).
---------------------------------------------------------------------------

NHTSA believes that, even in these situations where AEB performance
may be partially degraded, having AEB will still be beneficial. It may
not, for example, prevent a crash but it may reduce its severity by
slowing the

[[Page 43187]]

striking vehicle down. However, the agency took a conservative approach
and excluded cases such as those above from the target crash
population, and included only those cases in which AEB systems would
have the opportunity to perform optimally. This approach gives greater
confidence that the crashes included in the target crash population
would be prevented by having AEB-equipped vehicles.\35\
---------------------------------------------------------------------------

\35\ The PRIA discusses the rear-end crashes that were excluded
from the target population.
---------------------------------------------------------------------------

The result is that out of the 550,000 annual police reported
crashes involving heavy vehicles, approximately 60,000 annually are
rear-end crashes in which the heavy vehicle was the striking vehicle.
Thus, if heavy vehicles were equipped with AEB, a portion of these
60,000 crashes could be prevented. These 60,000 crashes, between 2017
and 2019, resulted in an annual average of approximately 388
fatalities, 30,000 injuries, and 84,000 PDOVs.
By requiring ESC for most class 3 through 6 vehicles, the proposed
rule would affect approximately 17,000 rollover and loss of control
crashes. These crashes resulted in 178 fatalities, 4,000 injuries, and
13,000 PDOVs, a portion of which could be prevented if class 3 through
6 heavy vehicles were equipped with ESC. These numbers are set forth in
Table 7.

Table 7--Target Crash Population
----------------------------------------------------------------------------------------------------------------
Crashes Fatalities Injuries PDOVs
----------------------------------------------------------------------------------------------------------------
AEB............................................. 60,000 388 30,000 84,000
ESC............................................. 17,000 178 4,000 13,000
----------------------------------------------------------------------------------------------------------------

III. Efforts To Promote AEB Deployment in Heavy Vehicles

Unlike with light vehicles in the U.S., there is currently no
voluntary commitment by heavy vehicle manufacturers to begin installing
AEB on all new vehicles.\36\ Nor is there a program similar to NHTSA's
New Car Assessment Program (NCAP) for heavy vehicles. However, NHTSA
and FMCSA have researched heavy vehicle AEB. In addition, Congress,
other governmental agencies, and a variety of stakeholders recognize
that this technology has the potential to reduce the fatalities,
injuries, and property damage associated with heavy vehicle rear-end
crashes. The installation rate of AEB in the U.S. vehicle fleet has
gradually increased, and the latest generations of the technology are
higher performing than the original implementations.
---------------------------------------------------------------------------

\36\ On March 17, 2016, NHTSA and the Insurance Institute for
Highway Safety (IIHS) announced a commitment by 20 automakers
representing more than 99 percent of the U.S. auto market to make
lower speed AEB a standard feature on virtually all new cars no
later than Sept 1, 2022. https://www.nhtsa.gov/press-releases/us-dot-and-iihs-announce-historic-commitment-20-automakers-make-automatic-emergency.
---------------------------------------------------------------------------

A. NHTSA's Foundational AEB Research

NHTSA has been studying emergency braking technologies since
manufacturers first introduced these technologies over fifteen years
ago. NHTSA has recognized the safety potential of heavy vehicle AEB for
many years and continued to research this technology as it evolved from
early generations to its current state. As part of NHTSA's efforts to
better understand these new crash avoidance technologies, NHTSA
sponsored and conducted numerous research projects focused on AEB and
FCW for heavy trucks. NHTSA conducted testing at its in-house testing
facility, the Vehicle Research and Test Center, to examine the
performance of AEB in different combinations of crash scenarios and
speeds.
NHTSA's foundational knowledge of braking technology was built on a
long history of work on FMVSS No. 105, ``Hydraulic and electric brake
systems,'' No. 121, ``Air brake systems,'' and No. 136, ``Electronic
stability control systems for heavy vehicles.''
FMVSS No. 105 applies to multipurpose passenger vehicles, trucks,
and buses with a GVWR greater than 3,500 kg (7,716 lbs.) that are
equipped with hydraulic or electric brake systems. This standard sets
performance requirements for, among other things, maximum stopping
distance, anti-lock braking systems, stability and control under
braking (including a curved and wet road surface), and recovery from
brake fade.\37\
---------------------------------------------------------------------------

\37\ Brake fade events are associated with speed control on
roads with steep or gradual but long downgrades. As brake
temperature increases in a drum, its diameter expands as the metal
heats up; this means the brake shoe displacement must also increase
to be effective. Eventually, the shoe reaches the displacement
limit, and then brake effectiveness drops off.
---------------------------------------------------------------------------

FMVSS No. 121 applies to trucks, buses, and trailers equipped with
air (pneumatic) brake systems, with a few exceptions for special
vehicle types. Although NHTSA sets no standards regarding the choice
between using hydraulic, electric, or air brakes, vehicles with a
larger size and load carrying capacity are more likely to have air
brakes. Thus, air brakes are typically installed on some class 6 and
most class 7-8 vehicles. Lower classes often use hydraulic brakes. A
few examples of the requirements in FMVSS No. 121 are maximum stopping
distance, having ABS, maintaining stability and control when braking to
a stop on a curved and wet roadway test surface, recovering from brake
fade, and having an emergency (backup) brake system.
FMVSS No. 136 establishes performance and equipment requirements
for electronic stability control systems on truck tractors and certain
large buses, for the purpose of reducing crashes caused by rollover or
by loss of directional control. This standard currently applies to
truck tractors and certain large buses with a GVWR greater than 11,793
kilograms (26,000 lbs.). FMVSS No. 136 requires vehicles to be equipped
with an ESC system, and to meet several minimum performance
requirements. For example, when driven on a specified J-shaped test
lane under a variety of specified conditions and parameters which
induce ESC activation, the wheels of the heavy vehicle must remain
within the lane.

B. NHTSA's 2015 Grant of a Petition for Rulemaking

In October 2015, NHTSA granted a petition for rulemaking from the
Truck Safety Coalition, the Center for Auto Safety, Advocates for
Highway and Auto Safety, and Road Safe America. This petition requested
``the commencement of a proceeding to establish a safety regulation to
require the use of [FCW and AEB] on all vehicles (trucks and buses)
with a gross vehicle weight rating (GVWR) of 10,000 pounds (lbs.) or
more.'' The petitioners maintained that AEB has important benefits and
is a technology that has been improving in performance, but that a
regulation is needed to optimize the benefits of the

[[Page 43188]]

technology and increase the frequency of installation in heavy
vehicles. The agency granted this petition on October 16, 2015, noting
that NHTSA's research and evaluation were ongoing, and initiated a
rulemaking proceeding with respect to vehicles with a GVWR greater than
4,536 kg (10,000 lbs.).\38\
---------------------------------------------------------------------------

\38\ Grant of petition for rulemaking, 80 FR 62487 (October 16,
2015).
---------------------------------------------------------------------------

C. Congressional Interest

1. MAP-21
In July 2012, the Moving Ahead for Progress in the 21st Century Act
was enacted. MAP-21 included Subtitle G, the ``Motorcoach Enhanced
Safety Act of 2012.'' \39\ Section 32705 of MAP-21 directed the
Secretary (NHTSA, by delegation) to research and test forward and
lateral crash warning systems for motorcoaches and decide whether a
corresponding safety standard would accord with section 30111 of the
Safety Act. Section 32703(b)(3) directed the Secretary to consider
requiring motorcoaches to be equipped with stability enhancing
technology, such as electronic stability control, to reduce the number
and frequency of rollover crashes, and prescribe a standard if it would
meet the requirements and considerations of sections 30111(a) and (b)
of the Safety Act.\40\ In response, NHTSA issued FMVSS No. 136,
requiring ESC for certain truck tractors and buses (including
motorcoaches) with a GVWR greater than 13,154 kg (26,000 lbs.).
---------------------------------------------------------------------------

\39\ Public Law 112-141, Sec. 32705.
\40\ Section 32703(b) required a regulation not later than two
years after the date of enactment of the Act if DOT determined that
such standard met the requirements of the Safety Act.
---------------------------------------------------------------------------

2. Bipartisan Infrastructure Law
In November 2021, the Bipartisan Infrastructure Law (BIL) was
signed into law. Section 23010 of BIL is dedicated to AEB. Section
23010(a) of BIL defines an AEB system as a system on a commercial motor
vehicle that, based on a predefined distance and closing rate with
respect to an obstacle in the path of the vehicle, alerts the driver of
an obstacle and, if necessary, applies the brakes automatically to
avoid or mitigate a collision with that obstacle.
Section 23010(b) requires the Secretary to prescribe an FMVSS to
require all commercial motor vehicles \41\ subject to FMVSS No. 136 (or
a successor regulation) to be equipped with an AEB system. The FMVSS is
also required to establish performance standards for AEB systems. BIL
directs the Secretary to prescribe the standard not later than two
years after the date of enactment of the Act.
---------------------------------------------------------------------------

\41\ As defined in 49 U.S.C. 31101, ``commercial motor vehicle''
means a self-propelled or towed vehicle used on the highways in
commerce principally to transport passengers or cargo, if the
vehicle has a gross vehicle weight rating or gross vehicle weight of
at least 10,001 pounds, whichever is greater; is designed to
transport more than 10 passengers including the driver; or is used
in transporting material found by the Secretary of Transportation to
be hazardous and transported in a quantity requiring placarding
under regulations.
---------------------------------------------------------------------------

Under Section 23010(b)(2), prior to prescribing the FMVSS, the
Secretary is required to conduct a review of AEB systems in use in
applicable commercial motor vehicles and address any identified
deficiencies in those systems in the rulemaking proceeding, if
practicable. In addition, the Secretary is required to consult with
representatives of commercial motor vehicle drivers to learn about
their experience with AEB (including malfunctions and/or unwarranted
activations).
This NPRM is issued to meet these provisions of the BIL. NHTSA
conducted a review of AEB systems in use in commercial motor vehicles
to identify limits in those systems. A memorandum summarizing this
review has been placed in the docket for this NPRM and has informed the
development of the proposal. NHTSA is also currently conducting
research to study drivers' experiences with collision mitigation
technologies, including AEB. Comments are requested on the feasibility
of mandating AEB for commercial motor vehicles with GVWR greater than
10,000 pounds which are not currently subject to FMVSS No. 136. This
NPRM requests comments from representatives of commercial motor vehicle
drivers, and drivers themselves, regarding the experience with the use
of AEB systems. This NPRM also includes a series of questions in
section VII.E on which NHTSA seeks comment to obtain information about
drivers' experiences with AEB (including malfunctions and/or
unwarranted activations).
Section 23010(c) of the BIL relates to the regulations of FMCSA,
which regulate the operation of commercial motor vehicles. BIL requires
an FMCSR ensuring that the AEB systems required by the FMVSS for new
commercial vehicles subject to FMVSS No. 136 be in use at any time
during which the vehicle is in operation. This NPRM proposes this
FMCSR.\42\
---------------------------------------------------------------------------

\42\ FMCSA has also created an apprenticeship program for novice
drivers of commercial motor vehicles pursuant to the BIL. The
program requires novice drivers to operate vehicles that possess an
active braking collision mitigation system, such as AEB. 87 FR 2477,
January 14, 2022.
---------------------------------------------------------------------------

Finally, section 23010(d) of BIL requires DOT to complete a study
on equipping a variety of commercial motor vehicles not currently
required to comply with FMVSS No. 136 with AEB. This study is to
include an assessment of the feasibility, benefits, and costs
associated with installing AEB on these vehicles. As discussed in
greater detail later, the analysis accompanying this NPRM fulfills this
requirement.

D. IIHS Effectiveness Study

In a 2020 report, the Insurance Institute for Highway Safety
studied the effectiveness of FCW and AEB technology on class 8 trucks
and concluded that safety will improve if more trucks have these
technologies installed.\43\ IIHS used data extracted from video camera
footage and crash rates of police-reportable crashes. While the study
sample did not contain a large number of severe crashes, FCW and AEB
were still associated with significant reductions in rear-end crashes
involving trucks. On average, between the time of collision and moment
of system intervention, the velocity of the striking vehicle was
reduced by greater than 50 percent. The study concluded that safety
would improve if more trucks had these technologies installed.\44\ The
IIHS study was limited to class 8 trucks and involved certain fleets
and drivers which may not necessarily be representative of the U.S.
fleet as a whole. Because of this limitation, NHTSA could not use the
findings to calculate the potential benefits of this proposal.
---------------------------------------------------------------------------

\43\ Teoh, Eric R. (2020, September). Effectiveness of front
crash prevention systems in reducing large truck crash rates.
Arlington, VA: Insurance Institute for Highway Safety. Available at
https://www.iihs.org/topics/bibliography/ref/
2211#:~:text=Results%3A%20FCW%20was%20associated%20with,%25%20for%20r
ear%2Dend%20crashes. (last accessed August 30, 2022).
\44\ Id.
---------------------------------------------------------------------------

E. DOT's National Roadway Safety Strategy (January 2022)

This NPRM takes a crucial step in implementing DOT's January 2022
National Roadway Safety Strategy to address the rising numbers of
transportation deaths occurring on this country's streets, roads, and
highways.\45\ At the core of this strategy is the Department-wide
adoption of the Safe System Approach, which focuses on five key
objectives: safer people, safer roads, safer vehicles, safer speeds,
and post-crash care. The Department will launch new programs,
coordinate and improve existing programs, and adopt a

[[Page 43189]]

foundational set of principles to guide this strategy.
---------------------------------------------------------------------------

\45\ https://www.transportation.gov/sites/dot.gov/files/2022-01/USDOT_National_Roadway_Safety_Strategy_0.pdf (last accessed August
23, 2022).
---------------------------------------------------------------------------

The National Roadway Safety Strategy highlights new priority
actions that target our most significant and urgent problems and are,
therefore, expected to have the most substantial impact. One of the key
Departmental actions to enable safer vehicles is initiating a
rulemaking to require AEB on heavy trucks. This NPRM proposes a Federal
Motor Vehicle Safety Standard to require AEB on heavy trucks and other
heavy vehicles.

F. National Transportation Safety Board Recommendations

The National Transportation Safety Board (NTSB) included AEB for
commercial vehicles in its 2021-2023 Most Wanted List.\46\ Among other
things, NTSB stated that NHTSA should complete standards for AEB in
commercial vehicles and require this technology in all highway vehicles
and all new school buses.
---------------------------------------------------------------------------

\46\ NTSB Most Wanted List, https://www.ntsb.gov/Advocacy/mwl/Pages/mwl-21-22/mwl-hs-04.aspx (last accessed August 23, 2022).
---------------------------------------------------------------------------

In 2015, NTSB issued a special investigation report,\47\ which
summarized previous, as well as new, findings related to AEB in a
variety of vehicles. Regarding heavy vehicles, this report presented
the following recommendation to NHTSA:
---------------------------------------------------------------------------

\47\ National Transportation Safety Board. 2015. The Use of
Forward Collision Avoidance Systems to Prevent and Mitigate Rear-End
Crashes. Special Investigation Report NTSB/SIR-15-01. Washington,
DC. Available at https://www.ntsb.gov/safety/safety-studies/Documents/SIR1501.pdf (last accessed August 22, 2022).
---------------------------------------------------------------------------

H-15-05: Complete, as soon as possible, the development
and application of performance standards and protocols for the
assessment of forward collision avoidance systems in commercial
vehicles.
In a 2018 special investigation report,\48\ the NTSB discussed two
severe accidents involving school buses. In the conclusion of the
report, the NTSB stated that AEB could have helped mitigate the
severity of one of the accidents, and that ESC could have helped
mitigate the other. Accordingly, the following safety recommendations
were made or restated to NHTSA:
---------------------------------------------------------------------------

\48\ National Transportation Safety Board. 2018. Selective
Issues in School Bus Transportation Safety: Crashes in Baltimore,
Maryland, and Chattanooga, Tennessee. NTSB/SIR-18/02 PB2018-100932.
Washington, DC. Available at https://www.ntsb.gov/investigations/AccidentReports/Reports/SIR1802.pdf (last accessed August 22, 2022).
---------------------------------------------------------------------------

H-18-08: Require all new school buses to be equipped with
collision avoidance systems and automatic emergency braking
technologies.
H-11-7: Develop stability control system performance
standards for all commercial motor vehicles and buses with a gross
vehicle weight rating greater than 10,000 pounds, regardless of whether
the vehicles are equipped with a hydraulic or a pneumatic brake system.
H-11-8: Once the performance standards from Safety
Recommendation H-11-7 have been developed, require the installation of
stability control systems on all newly manufactured commercial vehicles
with a gross vehicle weight rating greater than 10,000 pounds.

G. FMCSA Initiatives

FMCSA has been engaged in activities to advance the voluntary
adoption of AEB for heavy vehicles, primarily through the Tech-Celerate
Now (TCN) program. This program focuses on accelerating the adoption of
Advanced Driver Assistance Systems (ADAS), such as AEB, by the trucking
industry to reduce fatalities and prevent injuries and crashes, in
addition to realizing substantial return-on-investment through reducing
costs associated with such crashes for the motor carrier. Initiated in
September 2019 and completed in February 2022, the first phase of this
program encompassed research into ADAS technology adoption barriers; a
national outreach, educational, and awareness campaign; and data
collection and analysis.
Outreach accomplishments included development of training materials
for fleets, drivers, and maintenance personnel related to AEB
technology and return-on-investment (ROI) guides; educational videos on
ADAS braking, steering, warning, and monitoring technologies; a web-
based TCN ADAS-specific ROI calculator; four articles on ADAS
technologies; and a program website to host the training materials.
As part of the national outreach campaign, the program was promoted
on social media including LinkedIn and Twitter, and FMCSA conducted
presentations and booth exhibitions at conferences, webinars, and
virtual meetings. Recent efforts have included discussion of a safety
effective analysis project that is using two years of naturalistic data
collected from AEB and other ADAS technologies at the American Trucking
Associations Technology and Maintenance Council's 2022 Annual meeting,
the 2022 Midwest Commercial Vehicle Safety Summit, and the 2022
Southeast Commercial Vehicle Safety Summit. The results of this project
are expected be published late in calendar year 2023.
Planning is underway for the second phase of the TCN program, which
includes an expanded national outreach and education campaign,
additional research into the barriers to ADAS adoption by motor
carriers, and evaluation of the outreach campaign.

IV. NHTSA and FMCSA Research and Testing

A. NHTSA-Sponsored Research

The following are brief summaries of some of the research NHTSA
sponsored relating to strategies to avoid heavy vehicle collisions with
lead vehicles. The agency funded several research efforts to assess
collision avoidance systems, including AEB.
1. 2012 Study on Effectiveness of FCW and AEB
On August 2012, the University of Michigan Transportation Research
Institute (UMTRI) conducted a simulation study under a cooperative
agreement between NHTSA and AEB supplier WABCO.\49\ The objective of
the study was to estimate the safety benefits FCW and AEB systems
implemented on heavy trucks, including single-unit and tractor-
semitrailers. The study characterized technology, estimated a target
crash population, created a simulated reference crash database, and
assessed the impact of the technologies in a simulated environment.
These results were then applied to the target crash population. The
study not only simulated benefits for equipping heavy trucks with then-
available technology, but also simulated benefits for next and future
systems that were expected to have enhanced capabilities.
---------------------------------------------------------------------------

\49\ Woodrooffe, J., et al., ``Performance Characterization and
Safety Effectiveness Estimates of Forward Collision Avoidance and
Mitigation Systems for Medium/Heavy Commercial Vehicles,'' Report
No. UMTRI-2011-36, UMTRI (August 2012). Docket No. NHTSA-2013-0067-
0001, available at https://www.regulations.gov/document/NHTSA-2013-0067-0001.
---------------------------------------------------------------------------

The study simulated estimates based on next and future systems that
would utilize radar as the main sensor, and provided haptic, auditory,
and visual warnings to the driver (just as the current in-production
system). The in-production system could decelerate the vehicle up to a
maximum of 0.35g without any driver intervention. However, it could not
react to fixed objects (i.e., objects that were stationary before they
were in the range of the radar). The primary improvements expected for
the next system included the ability to react and brake at about 0.3g
in response to fixed objects and increased braking control authority on
stopped and moving vehicles to engage

[[Page 43190]]

the foundation brakes to produce as much as 0.6g of longitudinal
deceleration. The study used the same increased control authority on
stopped and moving vehicles as the next generation system, but required
the system to more aggressively react to fixed objects with
longitudinal deceleration of up to 0.6g.
Based on these capabilities, the study estimated that equipping all
tractor-semitrailers with AEB and FCW would reduce fatalities relative
to the base population for current, next, and future generation systems
by 24, 44, and 57 percent, respectively. Additionally, the predicted
reduction in injuries compared to the base population for current,
next, and future generation systems was estimated at 25, 47, and 54
percent, respectively. The combined annual benefit for straight truck
and tractor semitrailers, including property damage reduction for
current, next, and future generation systems was estimated at $1.4,
$2.6, and $3.1 billion, respectively.
The study concluded with multiple observations. The enhancements
depicted by the next generation system in comparison to the current
generation system were substantially larger than when comparing the
next generation to the future generation. These improvements were due
mainly to the ability of the system to react to fixed vehicles and the
increased braking. Overall, this evaluation depicted that the collision
mitigation measures studied would achieve significant benefits.
2. 2016 Field Study
NHTSA sponsored a field study with the Virginia Tech Transportation
Institute (VTTI) to assess the performance of heavy-vehicle crash
avoidance systems using 150 Class 8 tractor-trailers.\50\ The vehicles
were each equipped with a collision avoidance system from one of two
companies that included AEB and FCW. The purpose of the study was to
evaluate system reliability, assess driver performance over time,
assess overall driving behavior, provide data on real-world conflicts,
and generate inputs to a safety benefits simulation model.
---------------------------------------------------------------------------

\50\ See ``Field Study of Heavy-Vehicle Crash Avoidance
Systems'' (June 2016), available at https://www.nhtsa.gov/sites/nhtsa.gov/files/812280_fieldstudyheavy-vehiclecas.pdf (last accessed
June 3, 2022).
---------------------------------------------------------------------------

The vehicles were operated by drivers for one year with a total of
over 3 million miles travelled. Each vehicle was equipped with a data
acquisition system that collected roadway-facing video, driver-facing
video, activations, and vehicle network data. About 85,000 hours of
driving and 885,000 activations were collected across all activation
types. Of the sampled 6,000 activations, 264 were AEB activations and
1,965 were impact alerts.
According to the study, safety benefits of collision avoidance
systems could be estimated based on data describing driver use of
systems and their responses to the activations. Since the systems
depict warnings through an audio and visual display, a precise model of
the benefits would show how fast drivers react and if reactions vary
based on warning type. For 84 percent of the AEB activations, the
driver reacted prior to the alert, and 13 percent of the time, the
driver responded to the alert. Drivers did not respond to 3 percent of
the AEB activations. Over 50 percent of the false AEB activations
received driver responses. Average driving speeds and headway distances
at the initiation of AEB activations prior to safety-critical events
were similar to values recorded for other activations. While at the
initiation of many warranted AEB activations, drivers had already
implemented braking, every warranted AEB activation did not receive a
driver reaction.
The analysis included a driver frustration assessment for each AEB
activation. This was a subjective assessment based on whether drivers
appeared to show frustration during an activation. Advisory warnings
resulted in lower percentages of general frustration. The highest
instances of frustration were noted during false activations with
frustration noted 11 percent of the time.
In summary, the study found that crash avoidance systems can be
effective in collision avoidance. Driver performance and behavior
exhibited almost no changes over time, and there was limited
frustration with the AEB activations. There were some limitations in
the study including varied calibration options between the systems, no
control group, different geographical locations, and unequal driving
time amongst participants.
3. 2017 Target Population Study
In 2017, NHTSA completed a study on a target population for AEB in
vehicles with a GVWR over 4,536 kg (10,000 pounds).\51\ The objective
of the study was to determine which forward collisions would
theoretically benefit from AEB if all vehicles over 4,536 kg (10,000
pounds) GVWR were equipped with the system. First, NHTSA reviewed
literature for then-existing AEB systems manufactured by Bendix and
Meritor. Although the systems varied in some ways, they shared a tiered
functionality approach, including the sequential use of auditory and
visible warnings, automatic torque reduction, application of the engine
retarder, and finally automatic brake application as needed.\52\ The
research efforts concentrated on the FCW and CIB elements.
---------------------------------------------------------------------------

\51\ See ``A Target Population for Automatic Emergency Braking
in Heavy Vehicles,'' available at https://crashstats.nhtsa.dot.gov/Api/Public/Publication/812390 (last accessed June 7, 2022).
\52\ See page 8 ``A Target Population for Automatic Emergency
Braking in Heavy Vehicles,'' available at https://crashstats.nhtsa.dot.gov/Api/Public/Publication/812390 (last
accessed June 7, 2022).
---------------------------------------------------------------------------

Second, collisions were sampled from NHTSA and FMCSA's Large Truck
Crash Causation Study \53\ for an engineering review because this
database provides comprehensive information on heavy vehicle collisions
in the United States. The engineering review focused on 29 crashes from
the Large Truck Crash Causation Study that involved injuries and
fatalities to determine whether FCW and/or CIB would be effective in
preventing the crash. Effectivity was defined as both reviewing
engineers determining that there was a 50 percent chance or greater
that the crash would be prevented. The analysis determined that FCW and
CIB would both be effective in preventing 17 of the 29 crashes, much
more often than cases in which only either was effective or neither was
effective. Considering a summary of the weighted effectiveness, the
combination of FCW and CIB were effective in 50 percent of the cases.
While FCW alone was effective in 23 percent of cases, there was a
significant 21 percent of cases where neither FCW nor CIB was
effective.\54\
---------------------------------------------------------------------------

\53\ See ``Large Truck Crash Causation Study,'' available at
https://www.fmcsa.dot.gov/safety/research-and-analysis/large-truck-crash-causation-study-analysis-brief (last accessed October 19,
2022).
\54\ Additionally, there was at least one case that consensus
was not reached regarding the effectiveness of CIB, and there was no
investigation of crashes of lower severity where only property
damage resulted.
---------------------------------------------------------------------------

Third, the outcomes from the first two phases allowed for the
development of filters to identify the categories of collisions that
AEB would improve. These filters were then implemented to collisions in
NHTSA's crash databases to approximate how many collisions annually AEB
could have prevented. A combination of data from the FARS and the GES
was used for the calculations while ensuring that an overlap in fatal
crashes was removed to prevent duplicate tallies. Vehicle collision
information for the United States

[[Page 43191]]

involving injuries and fatalities for years 2010 to 2012 was utilized
from these databases.\55\ Both injury-related and fatal collisions
totaled 5,457,387, and this total was filtered to determine the target
population. The filtering exclusions were made cautiously in order to
yield a conservative benefit estimate. Crashes during which the subject
vehicle departed from its original travel lane and the lead vehicle
maintained the lane were not included. Similarly, collisions involving
the lead vehicle changing from the original lane and the subject
vehicle remaining in its lane were excluded. Additional exclusions
included collisions on icy and snowy roads, situations where the lead
vehicle turns from a perpendicular street in front of the subject
vehicle, cases involving acceleration maneuvers to avoid collision,
collisions where the lead vehicle was obscured by an object, collisions
into motorcycles, and cases where the subject vehicle was traveling on
a curved road toward an object such as a guardrail.
---------------------------------------------------------------------------

\55\ LTCCS was not selected due to the age of the crash data,
for it is possible heavy vehicle collisions differ tremendously
since 2001. The UMTRI Trucks Involved in Fatal Accidents study
(https://deepblue.lib.umich.edu/bitstream/handle/2027.42/107389/48532_A56.pdf?isAllowed=y&sequence=1, last accessed June 3, 2022)
was excluded because its detailed information regarding vehicle
style and driving time is only provided for collisions involving
fatalities, where data for collisions of less severity involving
only injuries would not be available.
---------------------------------------------------------------------------

Fourth, the target population estimated in the third phase was
modified to reflect recent and probable future regulations. This
modification eliminated collisions that would be avoided based on the
implementation of other required technologies that had not yet
completely proliferated in heavy vehicles. Accounting for safety
equipment including ESC, ABS, and speed limiters allowed for the
overall target population to be modified to reflect the anticipated
number of future collisions. Crashes that were included in the final
future target population were those involving heavy vehicles in which
the rear-end crash resulted in injuries and fatalities. Further, the
crashes were refined to include only crashes where both vehicles
remained in the original lane after the crash was deemed imminent and
collisions where lane changes prior to crash imminency were allowed as
long as only one of the vehicles changed lanes. Additionally,
situations where the driver attempted to steer around the collision or
used insufficient braking were included.
After all adjustments were completed, the study estimated a target
population of 11,499 crashes annually involving 7,703 injured persons
and 173 fatalities. It also discussed possible sampling error as well
as three sources of uncertainty. However, the size of a target
population provided only an estimated upper bound to the benefits at
that time. The report added value in the detailed descriptions of
affected crashes and subpopulation breakouts that have traditionally
fed into benefits estimation.
4. 2018 Cost and Weight Analysis
In 2018, Ricardo Inc. completed a study sponsored by NHTSA that
focused on the cost and weight implications of requiring AEB on heavy
trucks. The study aimed to determine the product price, total system
cost, incremental consumer price, and weight of FCW and AEB systems on
heavy trucks to provide insight into the safety and efficiency benefits
of using the systems.\56\ The initial steps of the study were vehicle
research, vehicle segregation, and vehicle selection. Model year 2015-
2018 heavy vehicles manufactured by Ford, Cascadia, Volvo, Daimler, and
International LT were chosen for teardown examination and ranged in
mean annual sales from approximately 24,000 to 86,542. The associated
FCW and AEB systems installed on these vehicles were manufactured by
Delphi Technologies, Meritor, Bendix Commercial Vehicle Systems, and
Detroit Assurance (Daimler).
---------------------------------------------------------------------------

\56\ Ricardo, Inc. (2018), ``Cost and Weight Analysis of Heavy
Vehicle Forward Collision Warning (FCW) and Automatic Emergency
Braking (AEB) Systems for Heavy Trucks'' Van Buren Township, MI.
---------------------------------------------------------------------------

Service technician consultations, manuals, and OEM parts
descriptions were used to itemize components of the FCW and AEB
systems. Specific assessments of the related displays, sensors,
mounting hardware, and other elements of the FCW and AEB systems were
provided to prevent extraneous parts from being included in the cost
and weight evaluations. The cost and weight evaluations were executed
by a group of automotive system and integration experts, cost modeling
specialists, and procurement personnel. A bill of materials was
compiled using a ``teardown'' process to inventory the parts, define
manufacturing processes, and ascertain materials utilized. Specialized
cost software allowed for calculation of cost and weight.
In general, components that were not distinct to the FCW and AEB
systems were not included in the cost and weight evaluation. Therefore,
shared parts such as electronic control units and wiring harnesses were
not considered as additions if they were already incorporated into the
vehicle configuration without FCW/AEB. The manufacturing costs were
estimated, factoring in research and development, labor, material
costs, machinery, machine occupancy and tooling.
The five selected vehicles were the Ford F-Series Super Duty,
Freightliner M2-106, Freightliner Cascadia, International LT, and Volvo
VNL. While there was some overlap of similar components, the FCW and
AEB systems in the five selected vehicles had substantial variation
amongst the system mechanisms and functionality. Based on these
differences the vehicles were separated into four groups, and the
average manufacturing costs and weights were assessed for each
category. Overall, the average incremental cost to manufacturers for
these FCW/AEB systems ranged from $44.23 to $197.51; and associated
end-user prices ranged from $70.80 to $316.18. Additionally, the
average incremental weights ranged from approximately 0.46 to 3.10 kg.

B. VRTC Research Report Summaries and Test Track Data

1. Relevance of Research Efforts on AEB for Light Vehicles
AEB was first introduced on light vehicles. For this reason,
NHTSA's research and testing of AEB systems began with light vehicles
and was subsequently used to inform NHTSA's work on heavy vehicle AEB.
NHTSA conducted extensive research on AEB systems to support
development of the technology and eventual deployment in vehicles.
There were three main components to this work. Early research was
conducted on FCW systems that warn drivers of potential rear-end
crashes with other vehicles. This was followed by research into AEB
systems designed to prevent or mitigate rear-end collisions through
automatic braking.
NHTSA's earliest research on FCW systems began in the 1990s, at a
time when the systems were under development and evaluation had been
conducted primarily by suppliers and vehicle manufacturers. NHTSA
collaborated with industry stakeholders to identify the specific crash
types that an FCW system could be designed to address, the resulting
minimum functional requirements, and potential objective test
procedures for evaluation.\57\ In the late 1990s, NHTSA

[[Page 43192]]

worked with industry to conduct a field study, the Automotive Collision
Avoidance System Program. NHTSA later contracted with the Volpe
National Transportation Systems Center (Volpe) to conduct data analyses
of data recorded during that field study.\58\ From this work, NHTSA
learned about the detection and alert timing and information about
warning signal modality (auditory, visual, etc.) of FCW systems, and
predominant vehicle crash avoidance scenarios where FCW systems could
most effectively play a role in alerting a driver to brake and avoid a
crash. In 2009, NHTSA synthesized this research in the development and
conduct of controlled track test assessments on three vehicles equipped
with FCW.\59\
---------------------------------------------------------------------------

\57\ This research was documented in a report, ``Development and
Validation of Functional Definitions and Evaluation Procedures for
Collision Warning/Avoidance Systems,'' Kiefer, R., et al., DOT HS
808 964, August 1999. Additional NHTSA FCW research is described in
Zador, P.L., et al., ``Final Report--Automotive Collision Avoidance
System (ACAS) Program,'' DOT HS 809 080, August 2000; and Ference,
J.J., et al., ``Objective Test Scenarios for Integrated Vehicle-
Based Safety Systems,'' Paper No. 07-0183, Proceedings of the 20th
International Conference for the Enhanced Safety of Vehicles, 2007.
\58\ Najm, W.G., Stearns, M.D., Howarth, H., Koopmann, J., and
Hitz, J., ``Evaluation of an Automotive Rear-End Collision Avoidance
System,'' DOT HS 810 569, April 2006 and Najm, W.G., Stearns, M.D.,
and Yanagisawa, M., ``Pre-Crash Scenario Typology for Crash
Avoidance Research,'' DOT HS 810 767, April 2007.
\59\ Forkenbrock, G., O'Harra, B., ``A Forward Collision Warning
(FCW) Program Evaluation, Paper No. 09-0561, Proceedings of the 21st
International Technical Conference for the Enhanced Safety of
Vehicles, 2009.
---------------------------------------------------------------------------

NHTSA's research and test track performance evaluations of AEB
began around 2010. The agency began a thorough examination of the state
of forward-looking advanced braking technologies, analyzing their
performance and identifying areas of concern or uncertainty, to better
understand their safety potential. NHTSA issued a report \60\ and a
request for comments (RFC) seeking feedback on its CIB and DBS research
in July 2012.\61\ Specifically, NHTSA wanted to enhance its knowledge
further and help guide its continued efforts pertaining to AEB
effectiveness, test operation (including how to ensure repeatability
using a target or surrogate vehicle), refinement of performance
criteria, and exploration of the need for ``false positive'' tests to
minimize the unintended negative consequences of automatic braking in
non-critical driving situations where a crash was not imminent.
---------------------------------------------------------------------------

\60\ The agency's initial research and analysis of CIB and DBS
systems were documented in a report, ``Forward-Looking Advanced
Braking Technologies: An analysis of current system performance,
effectiveness, and test protocols'' (June 2012). http://www.regulations.gov, NHTSA 2012-0057-0001.
\61\ 77 FR 39561.
---------------------------------------------------------------------------

NHTSA considered feedback it received on the RFC and conducted
additional testing to support further development of the test
procedures. The agency's work was documented in two additional reports,
``Automatic Emergency Braking System Research Report'' (August 2014)
\62\ and ``NHTSA's 2014 Automatic Emergency Braking (AEB) Test Track
Evaluations'' (May 2015),\63\ and in accompanying draft CIB and DBS
test procedures.\64\
---------------------------------------------------------------------------

\62\ https://www.regulations.gov, NHTSA 2012-0057-0037.
\63\ DOT HS 812 166.
\64\ https://www.regulations.gov, NHTSA 2012-0057-0038.
---------------------------------------------------------------------------

In 2016, NHTSA published a report identifying the most recurrent
AEB-relevant pre-crash scenarios for heavy vehicles. NHTSA identified
the three most recurrent situations as a heavy vehicle moving toward a
stopped lead vehicle, a heavy vehicle moving toward a slower moving
lead vehicle, and a heavy vehicle moving toward a lead vehicle that is
decelerating.\65\ These were the same three crash scenarios that had
been identified as the most prevalent AEB-relevant crash scenarios for
light vehicles.
---------------------------------------------------------------------------

\65\ Boday, C., et al., ``Class 8 Truck-Tractor and Motorcoach
Forward Collision Warning and Automatic Emergency Braking Test Track
Research--Phase I,'' Washington, DC: National Highway Traffic Safety
Administration (June 2016). Docket No. NHTSA[hyphen]2015-0024-0004.
---------------------------------------------------------------------------

2. Phase I Testing of Class 8 Truck-Tractors and Motorcoach
In 2016, NHTSA published its first report on track-testing of AEB
for heavy vehicles. The previous studies describing the test procedures
for light vehicles provided a framework for the establishment of heavy
vehicle test procedures. Since test procedures were not yet developed
for heavy vehicles, the goal of the research was to first adapt
existing testing protocols for light vehicle AEB and then follow these
adapted test procedures to quantify the performance of FCW and AEB
systems on heavy vehicles. The research was conducted in two phases.
NHTSA's Phase I work began with using a combination of the specific
test situations established for NHTSA's NCAP for assessment of FCW and
AEB systems and a modified version of the light vehicle test procedures
to create heavy vehicle draft research test procedures. NCAP tests
involved use of a strikable surrogate vehicle; however, for early heavy
vehicle Phase I work, NHTSA used a surrogate lead vehicle comprised of
canvas-covered foam to exhibit geometric and reflective features of the
rear of a passenger car. The testing for Phase I was performed with
four heavy vehicles outfitted with FCW and AEB, including three Class 8
truck-tractors and one Class 8 motorcoach. Specifically, the four Class
8 vehicles were a 2006 Volvo VNL 64T630 6x4 tractor, a 2006
Freightliner Century Class 6x4 tractor, a 2012 Freightliner Cascadia
6x4 tractor, and a 2007 MCI 56-passenger motorcoach (bus). Each vehicle
was equipped with ABS, ESC, FCW, and AEB systems. The 2006 and 2012
Freightliners and the MCI motorcoach employed a Meritor WABCO system,
and the 2006 Volvo was equipped with a Bendix Wingman Advanced system.
In general, the FCW and AEB systems utilized a front bumper mounted
sensor to detect objects in front of the vehicle and a display to warn
the driver with audio and visual alerts.
For each vehicle, NHTSA planned to run ten tests that are
summarized in Table 8. These situations covered the three most common
AEB-relevant pre-crash scenarios, as well as two false positive tests
and two tests performed at different weighted conditions.

Table 8--Phase I Test Scenarios
----------------------------------------------------------------------------------------------------------------
Lead vehicle Subject vehicle Lightly loaded Loaded at GVWR
Scenario speed (km/h) speed (km/h) (number of trials) (number of trials)
----------------------------------------------------------------------------------------------------------------
Lead vehicle Stopped................. 0 40 10 ..................
Lead Vehicle Moving.................. 16 40 10 10
Lead Vehicle Moving.................. 32 72 10 10
Lead Vehicle Decelerating............ 40 40 10 10
Lead Vehicle Decelerating............ 48 48 .................. 10
Lead Vehicle Decelerating............ 56 56 5 5
Steel Trench Plate False Positive.... N/A 40 5 5

[[Page 43193]]

Steel Trench Plate False Positive.... N/A 72 5 5
----------------------------------------------------------------------------------------------------------------

The test scenarios were defined by the initial speeds of the
subject vehicle and lead vehicle, and the starting headway distance
between the vehicle was monitored. For all the tested scenarios, the
test driver was instructed to modulate the accelerator pedal to
maintain the desired test speed until FCW initiated, upon which the
accelerator pedal input was removed. Steering was applied to maintain
lateral position test tolerances to the lead vehicle. Manual brake
pedal applications were only applied in certain scenarios where AEB was
not designed to activate, or an impact occurred with the leading
surrogate vehicle. Additionally, the previously described test
situations were conducted under both a lightly loaded condition and a
fully loaded vehicle weight condition (i.e., loaded up to the vehicle's
GVWR). Based upon potential damage to the subject vehicle, the
feasibility of completing each test scenario with the specific load,
and the fact that there was no discernable difference between the
performance under the lightly loaded and GVWR loaded conditions in the
trials executed, some of the speed combinations were not investigated
under both loads. The false positive tests were conducted by driving
the selected vehicles toward and over a steel trench plate to determine
if these commonly used road construction covers would trigger false
alerts or unintentional automatic braking.
Stationary lead vehicle testing was limited to the 2006 Volvo, as
it was equipped with the only system that would trigger an FCW on
stationary vehicles. At the time these evaluations were performed, none
of the systems tested were designed to activate AEB on stationary
vehicles. During every slower moving lead vehicle test, FCW was
activated. Additionally, every vehicle's AEB activated and avoided
collision during each slower moving test performed with a subject
vehicle speed of 40 km/h, and a lead vehicle speed of 16 km/h.
The lead vehicle decelerating test was used to evaluate all four
heavy vehicles, but multiple test adjustments had to be applied. For
the lead vehicle decelerating test performed with both the subject and
lead vehicle speeds of 40 km/h, the lead vehicle was slowed to 8 km/h
instead of a stop to account for the failure of the subject vehicles to
activate AEB for stopped vehicles. Once the change was implemented,
both the FCW and the AEB systems were activated, and speeds were
reduced. Collisions between the subject and lead vehicle did occur, but
testing of this scenario mainly led to the observation that the test
procedure's headway would also have to be adjusted since heavy vehicles
have different braking capabilities than light vehicles.
The steel trench plate false positive test was performed using the
2006 Volvo, 2006 Freightliner, and 2007 MCI at 40 km/h and 72 km/h.\66\
For both velocities examined, the 2006 Freightliner and 2007 MCI
exhibited no false positives in all five trials. However, the 2006
Volvo triggered unnecessary auditory warnings in all five trials for
both velocities. None of the false positive testing trials resulted in
AEB system activation.
---------------------------------------------------------------------------

\66\ The 2012 Freightliner was not evaluated with steel trench
plate scenario due to the short window that the vehicle was
available for testing.
---------------------------------------------------------------------------

During this early testing, the surrogate lead vehicle was towed
onto the test track and fixed laterally in the test lane via a low-
profile plastic monorail track. Initially, the test system employed a
low-stretch rope to pull the surrogate lead vehicle by a tow vehicle.
This configuration performed well in the slower moving lead vehicle
situation because the lead vehicle moves at a constant velocity,
allowing the tow rope to stay in tension. In contrast, when testing the
lead vehicle decelerating scenario, the tension in the tow rope was not
maintained once the tow vehicle decelerated, and subsequently the tow
rope was prone to becoming stuck under the surrogate lead vehicle. This
issue resulted in a loss of surrogate lead vehicle lateral stability
and consequently decreased the test repeatability.
To address this shortcoming, the foam surrogate lead vehicle was
replaced with a vertical cylinder wrapped with a layer of radar
reflective material secured to the top of a movable platform with more
consistent and stable deceleration properties. However, because the
cylinder was not representative of a real vehicle, this was identified
as needing further development and modification of the test protocols.
A significant portion of this early AEB testing focused on
developing draft research test procedures that could be used to safely
and objectively assess AEB performance. The development history of test
protocols is important for two reasons. First, it explains how NHTSA
came to the conclusion to propose the performance parameters described
in the notice and its basis that the performance requirements are
objective and practicable. Second, it provides some context as to some
of the limitations of early performance evaluations of AEB for heavy
vehicles. In general, this initial phase of research demonstrated that
the scenarios were generally repeatable and practical, and the tests
showed additional development would potentially result in better
controlled deceleration and stability of the lead vehicle.
3. Phase II Testing of Class 8 Truck-Tractors
NHTSA's primary objectives of the Phase II efforts were to continue
to develop the FCW and AEB test procedures executed in Phase I such
that they could be effectively utilized on a closed-course track test
to assess performance of heavy vehicle FCW and AEB systems. For this
testing, NHTSA used four Class 8, truck-tractors, three of which were
from Phase I. The fourth vehicle from Phase I, the MCI motorcoach, was
replaced with a 2016 Freightliner. Specifically, these subject vehicles
were a 2016 Freightliner, a 2012 Freightliner, a 2006 Volvo, and a 2006
Freightliner. Like in Phase I, all vehicles were outfitted with ABS,
ESC, FCW, and AEB systems. Both the 2006 and 2012 Freightliners
employed the Meritor WABCO system, the 2016 Freightliner had the
Detroit Assurance Safety System, and the 2006 Volvo utilized the Bendix
Wingman Advance system. All AEB systems on the selected vehicles
utilized radar installed on the front bumper and each AEB system
provided auditory and visual alerts. For Phase II testing, NHTSA used
the test scenarios from Phase I; however, a second false positive test
scenario was added. Specifically, NHTSA investigated a pass-through
test from

[[Page 43194]]

Europe's AEB requirements \67\ involving a subject vehicle being driven
in a central lane between two parked vehicles.
---------------------------------------------------------------------------

\67\ United Nations, ``Uniform provisions concerning the
approval of motor vehicles with regard to the Advanced Emergency
Braking Systems (AEBS)'' 2013. Available at https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2013/R131e.pdf (last accessed
February 10, 2023).
---------------------------------------------------------------------------

While other standards \68\ were considered for this research study,
the use of United States collision data and different testing goals led
to establishment of specific test procedures. While vehicle test speeds
were similar, with some overlap, NHTSA's test procedures included
higher velocity tests to be executed at 55 km/h with more
specifications governing the test conditions and test completion.
NHTSA's Phase II test scenario matrix is summarized in Table 9.
---------------------------------------------------------------------------

\68\ The following were among the standards considered:
International Organization for Standardization (ISO) 22839:2013,
``Intelligent transport systems--Forward vehicle collision
mitigation systems--Operation, performance, and verification
requirements; ISO 15623:2013, ``Intelligent transport systems--
Forward vehicle collision warning systems--Performance requirements
and test procedures,'' and SAE International recommended practice
J3029, ``Forward collision warning and mitigation vehicle test
procedure--Truck and bus.''
---------------------------------------------------------------------------

Phase II also further enhanced the testing of Phase I by
implementing a new strikable surrogate vehicle (SSV) system as the lead
vehicle. The SSV system was created for NHTSA's light vehicle AEB
assessment and was engineered to enhance test repeatability and lateral
stability in higher velocity tests.

Table 9--Phase II Test Scenarios
----------------------------------------------------------------------------------------------------------------
Lead vehicle Subject vehicle Lightly loaded Loaded at GVWR
Scenario speed (km/h) speed (km/h) (number of trials) (number of trials)
----------------------------------------------------------------------------------------------------------------
Lead Vehicle Stopped................. 0 40 6 8
Lead Vehicle Moving.................. 0 40 8 8
Lead Vehicle Moving.................. 35 75 8 8
Lead Vehicle Decelerating............ 40 40 8 8
Lead Vehicle Decelerating............ 55 55 6 or 8 6 or 8
Steel Trench Plate False Positive.... N/A 40 8 8
Steel Trench Plate False Positive.... N/A 75 8 8
Stationary Vehicle False Positive.... N/A 50 8 8
----------------------------------------------------------------------------------------------------------------

The SSV served as the lead vehicle or the vehicle test device (VTD)
in the AEB tests. The rear of the SSV was designed to depict features
of a typical passenger car. The carbon fiber surrogate exemplified
these aspects, considering physical measurements, reflective
properties, and visual characteristics. Its structure was not only
developed to be detected as a real vehicle by the AEB systems, but it
was also intended to endure wind gusts and recurrent impacts up to
approximately 40 km/h. The required surrogate test velocities and
deceleration of the VTD were achieved by a tow vehicle equipped with a
brake controller in conjunction with a towed two-rail track used to
move the SSV during the test.
NHTSA implemented changes in the test procedures from Phase I to
Phase II. The Phase II test procedures contained more detail as input
from within NHTSA and data collected during both phases of heavy
vehicle research were used to develop and refine the procedures. For
example, the test procedures contained structure for test scenario
descriptions, minimum data channels to collect, and general testing
requirements (e.g., ambient temperature range, wind, speed, brake
burnish, etc.). Definitions were added for when the initial test
conditions started, and more detail was added to the definition of when
a test trial ended. The test conditions were established to be on dry,
straight roadways in the daylight, based on a previous analysis of
crash data and observed safety critical events in field operation
testing. FCW activation, AEB activation, collision detection, and
accelerator pedal release time were measured in the tests. Similar to
Phase I, the testing of each scenario occurred under two different load
conditions.
After reviewing the Phase I test outcomes, NHTSA determined that
the lead vehicle stopped scenario could only be assessed by the latest
model year test vehicle outfitted with a capable AEB system. In Phase
II, the subject vehicle traveled 40 km/h and approached a stationary
lead vehicle in the same lane. Valid trials required the driver to
remain centered in the traveling lane and continue driving at the
target velocity until AEB was triggered. Once AEB was triggered, the
test driver fully released the accelerator pedal, and the driver was
not allowed to use the brake pedal of the test vehicle unless the
vehicle collided with the lead vehicle or if the AEB system completely
stopped the vehicle. The results showed that FCW was activated,
followed by automatic braking by the AEB system in all 8 trials
performed under the GVWR condition.
The lead vehicle moving test situation was evaluated at multiple
velocity combinations for all four test vehicles. During this test, the
subject test vehicle traveled at 40 km/h or 75 km/h and approached a
slower-moving lead vehicle traveling at 15 km/h or 35 km/h,
respectively, in the same lane. Valid trials required the driver to
remain centered in the traveling lane and continue driving at the
target velocity until AEB was triggered. Once AEB was triggered, the
test driver fully released the accelerator pedal. Testing for this
scenario was conducted for both lightly loaded and GVWR conditions. All
of the vehicles tested consistently issued FCW alerts and activated the
AEB systems; however, impacts occurred.
The lead vehicle decelerating situation was executed with all the
test vehicles except the 2006 Volvo due to its Phase I performance. Two
initial velocity and initial headway combinations of the subject and
lead vehicles were tested (i.e., 40 km/h and 80 m; 55 km/h and 23 m).
After a short period of steady state driving using constant speeds and
a constant headway, the lead vehicle was braked at approximately 0.3g
while traveling in the same lane as the subject vehicle. The subject
vehicle driver kept the subject vehicle centered in the traveling lane
and continued driving until AEB was triggered. Under both the lightly
loaded and GVWR load conditions testing was completed.
The lead vehicle decelerating test scenario with initial test
speeds of 55 km/h and 23 m of headway presented the greatest challenges
when compared to other tests. In Phase II, the initial headway was
changed from 30.5 m to 23

[[Page 43195]]

m to keep the lead vehicle from transitioning to a stopped lead vehicle
test scenario near the end of a test trial, as it did in Phase I
testing with a headway of 30.5 m. Testing for this scenario was
conducted for both lightly loaded and GVWR conditions and all four
vehicles. All of the vehicles consistently issued FCW alerts and
activated the AEB systems; however, most tests resulted in impact.
Two false positive test types were also conducted. The steel trench
plate scenario was executed at 40 km/h and 75 km/h for all test
vehicles. Each vehicle was evaluated in the GVWR load condition, but
only the 2016 Freightliner was also assessed in the lightly loaded
condition. Most of the vehicles did not exhibit any FCW or AEB
activations in these tests. However, one vehicle's FCW/AEB system
perceived the steel trench plate as a stationary object on the path of
travel and the reaction to this false positive detection was not
consistent in terms of warning time, brake initiation time, and
deceleration level. The second test involved two stationary vehicles in
lanes on either side of the test vehicle's travel lane; and only the
2012 Freightliner and the 2016 Freightliner were evaluated under the
GVWR load condition. Neither vehicle exhibited any false FCW or AEB
activations in this test.
Overall, the Phase II test results demonstrated the ability of the
vehicles and AEB systems tested to avoid contact in the lead vehicle
stopped and lead vehicle moving test scenarios at the different
velocities and achieve no collisions. These capabilities extended to
the lead vehicle decelerating tests performed at 40 km/h and a headway
of 80 m. In contrast, there was a much lower likelihood of these
vehicles avoiding contact with the lead vehicle using an initial speed
of 55 km/h and a headway of 23 m.
4. NHTSA's 2018 Heavy Vehicle AEB Testing
NHTSA conducted test track research in 2017 and 2018 on heavy
vehicles equipped with FCW and AEB. This section describes the third
phase of NHTSA's heavy vehicle testing and the results from three
single-unit trucks. These trucks included a class 3 2016 Freightliner
3500 Sprinter, a class 6 2017 International 4300 SBA 4x2, and a class 7
2018 Freightliner M2-106. The main goal of this third phase was to
develop objective test procedures for evaluating the performance of
heavy vehicles equipped with FCW and AEB systems on a closed course
test track.

Table 10--Phase III Test Scenarios
----------------------------------------------------------------------------------------------------------------
Lead vehicle Subject vehicle Initial
Scenario speed (km/h) speed (km/h) headway (m)
----------------------------------------------------------------------------------------------------------------
Lead Vehicle Stopped............................................ 0 40 55
Lead Vehicle Moving............................................. 15 40 35
Lead Vehicle Moving............................................. 35 75 56
Lead Vehicle Decelerating....................................... 40 40 80
Lead Vehicle Decelerating....................................... 55 55 23
Steel Trench Plate False Positive............................... N/A 40 56
Steel Trench Plate False Positive............................... N/A 75 105
Stationary Vehicle Pass-Through False Positive.................. N/A 50 60
----------------------------------------------------------------------------------------------------------------

In this third phase of research, the newly developed heavy vehicle
AEB test procedures included test conditions where the driver applies
the subject vehicle brakes while approaching a lead vehicle, but with
an input insufficient to prevent a rear-end crash, to complement the
previously developed scenarios.
The 2017 International 4300 was outfitted with a Bendix system
which includes FCW and AEB. This system was enhanced since Phase II of
NHTSA's research where, in Phase III, it used camera and radar to
engage automatic emergency braking and demonstrated the ability to
respond to traveling and stationary vehicles. The FCW provided alerts
at velocities greater than 8 and 15 km/h for moving and stationary
objects, respectively. For the AEB system to be engaged, the vehicle
had to travel above 25 km/h.
The 2018 Freightliner M2-106 was outfitted with an OnGuardACTIVE
Collision Mitigation system which features FCW and AEB. This system
used radar to engage automatic emergency braking and displayed the
ability to respond to traveling and stationary vehicles. The FCW
provided alerts with visual and auditory cues and a braking warning was
issued when the AEB was activated. In order for the AEB system to be
engaged, the vehicle had to travel above 25 km/h.
The study concluded that the test procedures were reproducible and
appropriate for heavy vehicles outfitted with FCW and AEB systems.
After Phase II, the test procedures and scenarios were updated and
applied to heavy vehicles with different weight classifications. The
inclusion of heavy vehicles with updated AEB systems in Phase III
allowed for evaluation of more systems in the lead vehicle stopped
scenario; during the lead vehicle stopped evaluations with no driver
braking, at least one vehicle experienced no collisions for all trials
tested. This showed improvement in comparison to the prior phase, which
was only able to test lead vehicle stopped on one vehicle and resulted
in multiple collisions. The lead vehicle moving scenario test results
also displayed improvement where the percentage of collisions decreased
in comparison to Phase II. Overall, the outcomes showed that the FCW/
AEB systems have the capacity for being able to decrease rear-end
collisions by exhibiting velocity reductions before a collision or
avoiding contact with a lead vehicle entirely. While some FCW false
positives were observed, the overall results depicted that the systems
have the ability to avoid collision on the test track.
The results of this research show that the test procedures are
applicable to many heavy vehicles and indicate that performance
improvements in heavy vehicles equipped with these safety systems can
be objectively measured.\69\ Further, this was the first phase of the
series that was able to apply the test procedures to single-unit trucks
across multiple weight classifications; and new test scenarios were
added.
---------------------------------------------------------------------------

\69\ Salaani, M.K., Elsasser, D., Boday, C., ``NHTSA's 2018
Heavy Vehicle Automatic Emergency Braking Test Track Research
Results,'' SAE International. J Advances & Current Practices in
Mobility 2(3):1685-1704, 2020, doi:10.4271/2020-01-1001.
---------------------------------------------------------------------------

5. NHTSA's Research Test Track Procedures
NHTSA's most recently published heavy vehicle AEB research test
track

[[Page 43196]]

procedures were published in March 2019 and evaluate AEB performance in
crash-imminent scenarios both with and without manual brake pedal
applications.\70\ These procedures, with some modification, form the
basis for the proposed test procedure in this NPRM.
---------------------------------------------------------------------------

\70\ Elsasser, D., Salaani, M.K., & Boday, C., ``Test track
procedures for heavy-vehicle forward collision warning and automatic
emergency braking systems,'' Report No. DOT HS 812 675, Washington,
DC: National Highway Traffic Safety Administration (March 2019).
Available at https://rosap.ntl.bts.gov/view/dot/42186/dot_42186_DS1.pdf (last accessed June 28, 2022).
---------------------------------------------------------------------------

The test procedures were based upon prior research and include the
lead vehicle stopped, lead vehicle moving, and lead vehicle
decelerating test scenarios, as well as the steel trench plate and
stationary vehicles false positive scenarios. The testing was divided
into three phases. First, the subject vehicle and the lead vehicle are
situated on the test track to the proper location and test velocity.
The second stage involves determining whether the vehicles have met the
proper starting test conditions to achieve valid and reproducible test
outcomes. The third and final stage serves to assess test validity and
system performance as well as response to any FCW or AEB triggers. In
the research test procedure, if an invalid test is detected, the test
is repeated until at least seven valid test attempts are completed.
Testing was executed during daylight, avoiding inclement weather and
irrelevant obstructions such as overhead signs, bridges, overpasses,
etc. For test procedures that include manual brake pedal applications,
the pedal was displaced at a rate of 254 mm/s to achieve a target
longitudinal acceleration of -3.0 m/s\2\, simulating a manual brake
pedal application of a panicked driver. Test procedures for brake pedal
input characterization and verification assessment are described for
checking uniformity and to ensure the set braking magnitude and
response can be achieved.
The lead vehicle stopped test scenario requires the test subject
vehicle to be driven toward the stationary lead vehicle at 40 km/h. The
subject vehicle is to maintain its velocity and relative lateral
position to the straight testing path as it advances toward the lead
vehicle. When the time to collision is equal to 5 seconds there is a
nominal separation distance of 56 m between the front of the subject
vehicle and the rear of the lead vehicle. Once braking is initiated,
the accelerator pedal input of the subject vehicle is discontinued
fully within 0.5 seconds after the start of braking. For lead vehicle
stopped tests performed with insufficient brake pedal applications, the
brake pedal is applied at a time to collision of 1.51 seconds. The
point at which the brake pedal rate exceeds 50 mm/s is used to define
the beginning event of brake pedal input. The conclusion of testing is
marked by a collision between the subject and lead vehicle or the
subject vehicle stopping prior to colliding with the lead vehicle. The
test procedures are repeated until seven valid test trials are obtained
for each lead vehicle stopped test with and without brake pedal
applications, to obtain a total of 14 valid tests.
The test procedure for the lead vehicle moving scenario is similar
for its two vehicle speed combinations. The subject vehicle travels to
reach the target speed of 40 or 75 km/h for a minimum of 1 second; and
the lead vehicle travels at 15 or 35 km/h, respectively. Prior to
approaching the lead vehicle there should be a separation distance of
at least 100 m. Additionally, by a time to collision equal to 5
seconds, the separation range is 35 m for 40 km/h and 56 m for 75 km/h.
Once the subject vehicle encounters the lead vehicle and braking is
automatically initiated, the subject vehicle accelerator pedal was
fully released within 0.5 seconds.
The lead vehicle decelerating test procedure starts with the
subject vehicle traveling toward the lead vehicle while maintaining an
80 m separation distance. Both the subject vehicle and the lead vehicle
are required to reach and maintain a velocity of 40 km/h for at least 1
second while keeping the headway distance. Once the subject vehicle
encounters the lead vehicle and braking is initiated, the subject
vehicle accelerator pedal was fully released within 0.5 seconds. This
test procedure is repeated with similar steps for a 55 km/h velocity
and a 23 m separation distance.
In order to evaluate false positives, the steel trench plate test
scenario was executed at 40 and 75 km/h, and the stationary vehicles
test was completed at 50 km/h. For the seven test trials performed at
40 and 75 km/h, a short edge of the rectangular steel trench plate was
centered on the roadway about the x-axis. The subject vehicle was
driven toward the steel trench plate such that an initial 110.0 m
headway existed, and a nominal velocity of 40 or 75 km/h was maintained
for at least 1.0 second. The test initial test condition began when the
separation distance between the subject vehicle and steel trench plate
was 56 m and 105 m for 40 and 75 km/h, respectively. Once the subject
vehicle encountered the steel trench plate at a headway of 16.83 or
40.88 m for 40 and 75 km/h, respectively, the brakes of the subject
vehicle were engaged. The test ends when either the subject vehicle
drives over the steep trench plate or the subject vehicle stops before
crossing over the steel trench plate.
The preliminary conditions of the stationary vehicles test involved
two vehicles parked with a lateral separation of 4.5 m. These two
vehicles were faced in the forward direction of the test track and were
aligned. The subject vehicle was driven along the test track with a
100.0 m headway from the stationary vehicles. The subject vehicle was
then driven to maintain a velocity of 50 km/h for at least 1.0 second.
The starting test condition is a headway of 60 m where the steering
wheel of the subject vehicle was controlled to center the vehicle along
the test track. Once the subject vehicle encountered the stationary
vehicles at a range of approximately 23.74 m the subject vehicle
accelerator pedal was fully released within 0.5 seconds of the
initiation of braking.
6. 2021 VRTC Testing
The test track data that follows represents vehicle performance
with the latest generation AEB systems and the procedures and
conditions proposed in this NPRM largely match the procedures and
conditions used for this testing.
2021 Freightliner Cascadia
The 2021 Freightliner Cascadia was tested under the lead vehicle
stopped, lead vehicle moving, and lead vehicle decelerating scenarios
at the NHTSA VRTC in 2021. The GVT was used as the lead vehicle in
these test scenarios. The lead vehicle stopped scenario was executed at
multiple initial subject vehicle velocities from 20 km/h up to 95 km/h.
While contact with the VTD occurred at 20, 25, 30, and 35 km/h, there
were measurable speed reductions. At test velocities between 40 and 85
km/h, no collisions were observed. Collisions also occurred at 90 and
95 km/h, but the FCW at both speeds was issued earlier than 2 seconds
before contact. Ten additional test trials were conducted at 40 km/h,
and only one trial resulted in contact. Four additional test trials
were executed at 50, 60, 70, 80, and 85 km/h; in all four trials, there
were no collisions at three speeds and one collision at two speeds
(i.e., 80 and 85 km/h, respectively) which ultimately resulted in a
speed reduction when compared to the other trials.
The lead vehicle moving scenario was performed at several
combinations of subject vehicle and lead vehicle initial speeds. The
first set of eight trials

[[Page 43197]]

involved the subject vehicle at a range of velocities of 30 km/h to 90
km/h and the initial speed of the lead vehicle was 20 km/h for each.
Contact occurred only at the 30 and 60 km/h test velocities. The
initial speeds for the subject vehicle and lead vehicle for the second
set of eight trials was 40 and 15 km/h, respectively. One of these
trials ended in a collision and this run exhibited a notably lower
speed reduction when compared to the other trials. The third and fourth
sets of trials included subject vehicle and lead vehicle initial
velocity combinations of 75 and 35 km/h and 80 and 12 km/h,
respectively, and contact was avoided in all trials. For the lead
vehicle decelerating scenario collision was avoided for all trials
during the 40 km/h test. Impact occurred during four out of five runs
in the 50 km/h test with an initial headway of 18 m. However, at the
longer headway lengths of 21, 23, 25, and 40 m there were no collisions
during the 50 km/h tests. Additionally, contact was avoided for the 80
km/h test with headway lengths of 23, 25, 28, 40, and 45 m.

Table 11--2021 Freightliner Cascadia Test Track Scenarios
------------------------------------------------------------------------
Lead vehicle Subject vehicle
Scenario speed (km/h) speed (km/h)
------------------------------------------------------------------------
Lead Vehicle Stopped................. 0 20-95
Lead Vehicle Moving.................. 20 30-90
Lead Vehicle Moving.................. 15 40
Lead Vehicle Moving.................. 35 75
Lead Vehicle Moving.................. 12 80
Lead Vehicle Moving.................. 32 80
Lead Vehicle Decelerating............ 40 40
Lead Vehicle Decelerating............ 50 50
Lead Vehicle Decelerating............ 55 55
Lead Vehicle Decelerating............ 80 80
------------------------------------------------------------------------

2021 Ram 5500
The class 5 2021 Ram 5500 was tested under the lead vehicle
stopped, lead vehicle moving, and lead vehicle decelerating scenarios
at the NHTSA VRTC in 2022. The tests performed for these scenarios
involved no manual brake application; and the GVT was used as the lead
vehicle. For the lead vehicle stopped scenario, the Ram truck avoided
collisions at 10, 20, 30, 40 km/h, while impact occurred during two of
the five trials in the 50 km/h test, although there was an
approximately 80 percent reduction in speed. In general, these results
seemed to align with limitations described in the vehicle owner's
manual that indicated that the system works up to 50 km/h. Testing up
to 80 km/h was not completed to avoid damage to the subject vehicle and
test equipment. During the lead vehicle moving scenario, the truck
avoided contact at 30, 40, 50, 60, 70, and 80 km/h. Impact did occur at
90 km/h, though there was a speed reduction of 63 percent. At 50 km/h,
the lead vehicle decelerating scenario resulted in consecutive impacts
with some speed reduction. Due to the repeated collisions, testing was
discontinued to prevent damage to the subject vehicle and the GVT.
NHTSA also tested The Ram 5500 under the three scenarios with
manual brake application. The lead vehicle stopped scenario resulted in
avoidance of contact for all trials at 30, 40, and 60 km/h. Collision
did occur at 50 km/h, though there was a speed reduction of
approximately 80 percent. The lead vehicle moving scenario resulted in
impact avoidance for all 40 to 90 km/h trials, but impact did occur
during the 100 km/h test. For the lead vehicle decelerating scenario,
impact occurred during the 50 km/h test with an initial headway of 40,
32, and 23 m. Collision also occurred for the 80 km/h test with a
headway of 40 m.

Table 12--2021 Ram 5500 Test Track Scenarios
------------------------------------------------------------------------
Lead vehicle Subject vehicle
Scenario speed (km/h) speed (km/h)
------------------------------------------------------------------------
Lead Vehicle Stopped................. 0 10-60
Lead Vehicle Moving.................. 20 30-100
Lead Vehicle Decelerating............ 50 50
Lead Vehicle Decelerating............ 80 80
------------------------------------------------------------------------

In general, no single vehicle avoided collisions at all speeds in
the tested scenarios. While one vehicle may have performed better at
lower speeds and the other better at higher speeds, the combination of
results from the individual vehicles showed positive results over a
range of speeds. Overall, the performance demonstrated that the AEB
technology has improved over time, as shown in Tables 13 and
14.^{71 72 73 74}
---------------------------------------------------------------------------

\71\ Phase 1--Boday, C., et al., ``Class 8 Truck-Tractor and
Motorcoach Forward Collision Warning and Automatic Emergency Braking
Test Track Research--Phase I,'' Washington, DC: National Highway
Traffic Safety Administration (June 2016). Docket No.
NHTSA[hyphen]2015-0024-0004.
\72\ Phase II- U.S. DOT/NHTSA- Class 8 Truck- Tractor and
Motorcoach Forward Collision Warning and Automatic Emergency Braking
System Test Track Research- Draft Report. Docket No. NHTSA-2015-
0024-0006.
\73\ Phase III--Salaani, M.K., Elsasser, D., Boday, C.,
``NHTSA's 2018 Heavy Vehicle Automatic Emergency Braking Test Track
Research Results,'' SAE International. J Advances & Current
Practices in Mobility 2(3):1685-1704, 2020, doi:10.4271/2020-01-
1001.
\74\ This information is available in the report titled ``NHTSA
Heavy Vehicle AEB Test Track Performance Data Summary Report--
2022,'' placed in the docket identified in the heading of this NPRM.

[[Page 43198]]

Table 13--Technology Improvement Over Time
[Class 7-8]
----------------------------------------------------------------------------------------------------------------
1st period-- 2nd period--2nd
Class 7-8 heavy vehicle capability introduction generation (2015) Current (2022)
----------------------------------------------------------------------------------------------------------------
FCW and AEB activate for moving Yes...................... Yes..................... Yes.
vehicles.
AEB can avoid contact at test No....................... Yes..................... Yes.
speeds up to 80 km/h in lead
vehicle moving scenarios.
AEB can avoid contact at test No....................... N/A..................... Yes.
speeds greater than 80 km/h in
lead vehicle moving scenarios.
FCW alerts for stopped vehicles.... Yes...................... Yes..................... Yes.
AEB activates for stopped vehicles. No....................... Yes..................... Yes.
AEB can avoid contact at test No....................... No...................... Yes.
speeds up to 80 km/h in lead
vehicle stopped scenarios.
AEB can avoid contact at test No....................... No...................... Yes.
speeds greater than 80 km/h.
----------------------------------------------------------------------------------------------------------------

Table 14--Technology Improvement Over Time
[Class 3-6]
------------------------------------------------------------------------
Class 3-6 heavy vehicle AEB
capability Up to 2015 2016-2022
------------------------------------------------------------------------
FCW and AEB activate for Yes................. Yes.
moving vehicles.
AEB can avoid contact at test No.................. Yes.
speeds up to 80 km/h in lead
vehicle moving scenarios.
AEB can avoid contact at test No.................. Yes.
speeds greater than 80 km/h
in lead vehicle moving
scenarios.
FCW alerts for stopped Yes................. Yes.
vehicles.
AEB activates for stopped No.................. Yes.
vehicles.
AEB can avoid contact at test No.................. No.
speeds up to 80 km/h in lead
vehicle stopped scenarios.
AEB can avoid contact at test No.................. No.
speeds greater than 80 km/h.
------------------------------------------------------------------------

C. NHTSA Field Study of a New Generation Heavy Vehicle AEB System

NHTSA has an ongoing field study with VTTI that aims to collect
naturalistic driving data of at least 150 heavy vehicles over a one-
year timeframe. The goal is to collect data from each driver
participant for a three-month segment of the year. This research has
very similar parameters and objectives as those described above for the
``Field Study of Heavy-Vehicle Crash Avoidance Systems'' study.
However, several years have elapsed since the data were collected for
the prior study; and the trucks included in this ongoing research
project are equipped with newer generation AEB systems, including
stationary object braking and system integration into instrument
clusters.
The data acquisition systems installed on the heavy vehicles will
allow VTTI to sample various system activations including AEB,
stationary object alerts and FCWs. The focus of the study's real-world
data collection and analysis is to ascertain an understanding of
vehicle performance, driver behavior, and driver adaptation. VTTI is
evaluating Bendix Commercial Vehicle Systems and Detroit Assurance
(Daimler) systems and the five objectives include evaluation of system
reliability, assessment of driver performance over time, assessment of
overall driving behavior, collection of data on real-world conflicts,
and generation of inputs to a safety benefits simulation model.
Preliminary results from the driver survey responses indicate that
many drivers agree that collision mitigation technology makes drivers
safer. Approximately 50 percent of drivers surveyed at least slightly
agree that AEB is beneficial and helps drivers avoid a crash.\75\
---------------------------------------------------------------------------

\75\ This information is available in a report titled ``HV AEB
Driver Exit Survey Summary as of August 31, 2022,'' which has been
placed in the docket for this rulemaking.
---------------------------------------------------------------------------

V. Need for This Proposed Rule and Guiding Principles

A. Estimating AEB System Effectiveness

In developing this NPRM, NHTSA has examined the effectiveness of
AEB, proposing only those amendments that contribute to improved crash
safety, and have considered the principles for regulatory decision-
making set forth in Executive Order 12866 (as amended), Regulatory
Planning and Review.
The effectiveness of AEB indicates the efficacy of the system in
avoiding a rear-end crash. This NPRM proposes to require heavy vehicles
to have AEB systems that enable the vehicle to completely avoid an
imminent rear-end collision under a set of test scenarios. One method
of estimating effectiveness would be to perform a statistical analysis
of real-world crash data and observe the differences in statistics
between heavy vehicles equipped with AEB and those not equipped with
AEB. However, this approach is not feasible currently due to the low
penetration rate of AEB in the on-road vehicle fleet. Consequently,
NHTSA estimated effectiveness of AEB systems using performance data
from the agency's vehicle testing. The agency assessed effectiveness
against all crash severity levels collectively, rather than for
specific crash severity levels (i.e., minor injury versus fatal).
The performance data derived from four different test vehicles was
used to estimate AEB effectiveness,\76\ and the agency is continuing
its effort to test a larger variety of vehicles to further evaluate AEB
system performance. These vehicles were subject to the same test
scenarios (stopped lead vehicle, slower-moving lead vehicle,
decelerating lead vehicle) that are proposed in this NPRM, and
effectiveness estimates are based on each vehicle's capacity to avoid a
collision during a test scenario. For example, if a vehicle avoided
colliding with a stopped lead vehicle in four out of five test runs,
its effectiveness in that scenario would be 80 percent. The test
results for each vehicle were combined
---------------------------------------------------------------------------

\76\ This information is available in the report titled ``NHTSA
Heavy Vehicle AEB Test Track Performance Data Summary Report--
2022,'' placed in the docket identified in the heading of this NPRM.

---------------------------------------------------------------------------

[[Page 43199]]

into an aggregate effectiveness value by vehicle class range and crash
scenario, as displayed in Table 15.

Table 15--AEB Estimated Effectiveness (Percent)
[By vehicle class range and crash scenario]
----------------------------------------------------------------------------------------------------------------
Stopped lead Slower-moving Decelerating
Vehicle class range vehicle lead vehicle lead vehicle
----------------------------------------------------------------------------------------------------------------
7-8............................................................ 38.5 49.2 49.2
3-6............................................................ 43.0 47.8 47.8
----------------------------------------------------------------------------------------------------------------

As shown in Table 15, after aggregating class 7 and class 8
together, the agency has estimated AEB would avoid 38.5 percent of
rear-end crashes for the stopped lead vehicle scenario, and 49.2
percent of slower-moving and decelerating lead vehicle crashes. For
class 3-6, AEB is estimated to be 43.0 percent effective against
stopped lead vehicle crashes and 47.8 percent against slower-moving and
decelerating lead vehicle crashes. These effectiveness values are the
values NHTSA used for assessing the benefits of this proposed rule.

B. AEB Performance Over a Range of Speeds Is Necessary and Practicable

The performance requirements proposed in this NPRM are designed
around the goal of realizing as much of the safety potential of AEB
systems, while remaining realistic and practicable both economically
and technically. AEB performance guidelines created outside of the
agency's rulemaking process appear not to have been created with these
same goals, and thus may not represent the optimal balance of safety
and practicability. Several AEB performance tests developed in the
private sector are limited to a maximum test speed of around 40 km/h
(25 mph), and do not test the capability of AEB system at highway
speeds.^{77 78}
---------------------------------------------------------------------------

\77\ IIHS Autonomous Emergency Braking Test Protocol (Version
I). Available at https://www.iihs.org/media/a582abfb-7691-4805-81aa-16bbdf622992/REo1sA/Ratings/Protocols/current/test_protocol_aeb.pdf.
(last accessed August 5, 2022).
\78\ SAE International Forward Collision Warning and Mitigation
Vehicle Test Procedure--Truck and Bus J3029_201510. (For more
details, see https://www.sae.org/standards/content/j3029_201510)
(last accessed August 5, 2022).
---------------------------------------------------------------------------

NHTSA considered two primary factors in selecting the proposed test
speed ranges. The first factor is the practical ability of AEB
technology to consistently operate and avoid contact with a lead
vehicle at the widest reasonable range of speeds. A larger range of
speeds would likely yield more safety benefits and would more
thoroughly test the capabilities of the AEB system. Furthermore, as
observed in vehicle testing for NHTSA research, AEB performance during
testing at higher speeds does not necessarily indicate what the same
system's performance will be at lower speeds. For example, NHTSA's
testing of the 2021 Freightliner Cascadia truck showed that the AEB
system was able to avoid a collision with the lead vehicle at test
speeds of 40 to 85 km/h, but not at speeds below 40 km/h. Thus, testing
over a range of speeds is necessary to more fully assess AEB
performance.\79\
---------------------------------------------------------------------------

\79\ This information is available in the report titled ``NHTSA
Heavy Vehicle AEB Test Track Performance Data Summary Report--
2022,'' placed in the docket identified in the heading of this NPRM.
---------------------------------------------------------------------------

The second factor is the practical limit of safely conducting
vehicle tests of AEB systems. Test data indicates that AEB performance
is less consistent, becoming less likely to avoid a collision when test
speeds approach or exceed the proposed upper limits, indicating that
testing at higher speeds than proposed would be beyond technological
feasibility.\80\
---------------------------------------------------------------------------

\80\ More detail on test data is discussed in the NHTSA and
FMCSA Research and Testing section.
---------------------------------------------------------------------------

NHTSA's testing must be safe and repeatable as permitted by track
conditions and testing equipment. For example, if the AEB system does
not intervene as required, or if test parameters inadvertently fall
outside of the specified limits, it should be possible to safely abort
the test. In the event the subject vehicle does collide with the lead
vehicle, it should not injure the testing personnel nor cause excessive
property damage. Additionally, test tracks may be constrained by
available space and there may be insufficient space to accelerate a
heavy vehicle up to a higher speed and still have sufficient space to
perform a test. Many types of heavy vehicles are not capable of
accelerating as quickly as lighter vehicles and reaching higher test
speeds may require longer stretches that exceed available testing
facilities. At approximately 100 km/h, the agency found that
constraints with available test track length, in conjunction with the
time required to accelerate the vehicle to the desired test speed, made
performing these higher speed tests with heavy vehicles logistically
challenging.\81\ The agency has tentatively concluded that at this time
the maximum practicable test speed is 100 km/h.
---------------------------------------------------------------------------

\81\ During testing of a 2021 Freightliner Cascadia at speeds
approaching 100 km/h, NHTSA experienced difficulty establishing
valid test conditions due to test facility use restrictions.
Facility use restrictions limited where emergency braking tests by
heavy vehicles and automated lead vehicle robots could co-operate,
thereby reducing the effective useable track length to less than
1100 meters.
---------------------------------------------------------------------------

The maximum speed of 100 km/h is included in the test speed range
when manual braking is present; the manual braking will reduce impact
speed if the FCW issues a warning and the AEB system does not activate
before reaching the lead vehicle. This would limit potential damage to
the test equipment and avoid injury to testing personnel. With no
manual braking, the maximum test speed is 80 km/h so that in the event
that the AEB system does not provide any braking at all, damage to the
subject vehicle and test equipment is reduced and potential injuries
avoided.
The stopped lead vehicle test scenario uses a no-manual-braking
test speed range of 10-80 km/h and a manual-braking test speed range of
70-100 km/h. Similarly, the slower-moving lead vehicle test scenario
uses subject vehicle speed ranges of 40-80 km/h for no manual-braking
and 70-100 km/h for manual braking, while the lead vehicle travels
ahead at a constant speed of 20 km/h. The lower end of the subject
vehicle test speed range is 40 km/h so that the subject vehicle is
traveling faster than the lead vehicle. The decelerating lead vehicle
tests are run at either 80 or 50 km/h. This latter test is performed at
two discreet speeds rather than at ranges of speeds because the main
factors that test AEB performance are the variation of headway, or the
distance between the subject vehicle

[[Page 43200]]

and lead vehicle, and how hard the lead vehicle brakes. Also, because
these tests contain a larger number of variables requiring more complex
test choreography, limiting the test to two discreet test speeds
reduces the number of potential test conditions and reduces potential
test burden. Together, these test speed ranges provide good coverage of
the travel speeds at which heavy vehicle rear-end crashes occur in the
real world, while reducing the potential risk and damage to test
equipment and vehicles and not exceeding the practical physical size
limits of test tracks.
Additionally, the agency is proposing that these requirements would
not apply at speeds below 10 km/h. NHTSA believes that there are real-
world cases where heavy vehicles are being maneuvered intentionally in
proximity of other objects at low-speed, and AEB intervention could be
in conflict with the vehicle operator's intention. For example, if an
operator intends to drive towards the rear of another vehicle in a
parking lot in order to park the vehicle near the other, automatic
braking during this parking maneuver would be unwanted. The agency
tentatively concluded that excluding speeds below 10 km/h from the AEB
requirement would allow these types of low-speed maneuvers. This
proposal does not require AEB systems to be disabled below 10 km/h.
However, publicly available literature from at least one manufacturer
shows that some or all of the AEB system functions are not available
below 15 mph (24 km/h), indicating that current manufacturers may have
similar considerations about low-speed AEB functionality.\82\ A lower
bound for FCW and AEB activation speed of 10 km/h is also consistent
with the lower bound testing proposed for light vehicle AEB and the
Euro NCAP rating program.\83\
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\82\ Bendix Wingman Fusion Brochure, or SD-61-4963 Service Data
manual for Bendix Wingman Fusion Driver Assistance System. Available
at https://www.bendix.com/media/documents/technical_documentsproduct_literature/bulletins/SD-61-4963_US_005.pdf (last accessed August 23, 2022).
\83\ Euro NCAP Test Protocol--AEB Car-to-Car systems v3.0.3
(April 2021). See https://cdn.euroncap.com/media/62794/euro-ncap-aeb-c2c-test-protocol-v303.pdf.
---------------------------------------------------------------------------

During each test run in any of the test scenarios, the vehicle test
speed will be held constant until the test procedure specifies a
change. NHTSA is proposing that vehicle speed would be maintained
within a tolerance range of 1.6 km/h of the specified test value. In
NHTSA's experience, both the subject vehicle and lead vehicle speeds
can be reliably controlled within the 1.6 km/h tolerance range, and
speed variation within that range yields consistent test results. A
tighter speed tolerance is unnecessary for repeatability and burdensome
as it may result in a higher test-rejection rate, without any greater
assurance of accuracy of the test track performance.
NHTSA's vehicle testing suggested that the selected speed ranges
for the various scenarios are within the capabilities of at least some
recent model year AEB-equipped production vehicles.\84\ While these
current AEB systems perform a bit differently depending on the vehicle,
given that this notice proposes a lead time for manufacturers to come
into compliance with the proposed performance requirement, the agency
expects that future model year performance in accordance with a final
rule schedule will be achievable.
---------------------------------------------------------------------------

\84\ This information is available in the report titled ``NHTSA
Heavy Vehicle AEB Test Track Performance Data Summary Report--
2022,'' placed in the docket identified in the heading of this NPRM.
---------------------------------------------------------------------------

C. Market Penetration Varies Significantly Among Classes of Heavy
Vehicles

Though the presence of AEB in heavy vehicles has increased over the
years, many new heavy vehicles sold in the U.S. are not equipped with
AEB. Market data obtained by NHTSA indicates that although AEB is
likely equipped on the majority of class 8 vehicles and is available on
nearly all class 3 and class 4 vehicles, few of class 5 and 6 vehicles
come equipped with any type of AEB system. In addition, though the
capabilities of these AEB systems have also improved over time, there
has been no set of standardized performance metrics in the U.S. that
manufacturers could use as a benchmark to meet. This NPRM proposes
standard performance metrics that would meet a motor vehicle safety
need.
Among the variety of heavy vehicle types, class 7 and 8 truck
tractors have been the earliest to voluntarily adopt AEB systems. These
vehicles are (with some exceptions) already subject to the electronic
stability control requirement in FMVSS No. 136 and contain fewer
variations in vehicle type, configuration, and operational pattern. It
was estimated that as of 2013 only 8 to 10 percent of class 8 trucks in
the U.S. were equipped with this technology.\85\ In 2017 a FMCSA report
extrapolated available information to estimate that 12.8 percent of the
entire on-road fleet of class 8 trucks in the United States were
equipped with an AEB system,\86\ while the industry estimated that up
to 15 percent of class 8 trucks were equipped with AEB.\87\ More
recently, a survey of public information on AEB availability for heavy
vehicles reveals that this technology is becoming more prevalent on new
trucks. In 2016, Peterbilt announced the option of AEB in its class 8
model 579 truck tractor, and then made the technology standard in
2019.^{88 89} As of 2017, Volvo Trucks made AEB standard
equipment on all of its class 8 truck tractor models, as a part of its
Volvo Active Driver Assist safety package.\90\ While several fleets or
manufacturers have made AEB standard, it remains an option for some
class 8 vehicles, such as the Peterbilt single-unit truck models 337
and 348.\91\ Data from a recent study indicates that the large majority
of class 8 vehicles sold from 2018 until mid-2022 had AEB as a standard
feature, and that the top ten selling class 8 vehicles all include
standard AEB.\92\
---------------------------------------------------------------------------

\85\ National Transportation Safety Board. 2015. ``Special
Investigation Report: The Use of Forward Collision Avoidance Systems
to Prevent and Mitigate Rear-End Crashes.'' Report No. NTSB/SIR-15/
01 PB2015-104098. Washington, DC.
\86\ Grove, K., et al., ``Research and Testing to Accelerate
Voluntary Adoption of Automatic Emergency Braking (AEB) on
Commercial Vehicles,'' VTTI (May 2020). Available at https://rosap.ntl.bts.gov/view/dot/49335 (last accessed June 9, 2022).
\87\ Cannon, J., ``Automatic emergency braking is the next
generation of driver assist technologies,'' Commercial Carrier
Journal, December 14, 2017. https://www.ccjdigital.com/business/article/14936178/future-of-automatic-emergency-braking-driver-assist-tech.
\88\ https://www.peterbilt.com/about/news-events/news-releases/peterbilt-introduces-bendix-wingman-fusion-advanced-safety-system
(last accessed August 23, 2022).
\89\ https://www.peterbilt.com/about/news-events/peterbilt-trucks-introduce-bendix-wingman-fusion-standard (last accessed
August 23, 2022).
\90\ https://www.volvotrucks.us/news-and-stories/press-releases/
2017/july/volvo-active-driver-assist-now-standard/
#:~:text=Volvo%20Active%20Driver%20Assist%20is%20now%20standard%20equ
ipment,is%20fully%20integrated%20with%20Volvo%E2%80%99s%20Driver%20In
formation%20Display (last accessed August 23, 2022).
\91\ https://www.peterbilt.com/about/news-events/peterbilt-announces-bendix-wingman-fusion-medium-duty (last accessed August
23, 2022).
\92\ This information is available in the S&P Global's
presentation titled ``MHCV Safety Technology Study,'' which has been
placed in the docket identified in the heading of this NPRM.
---------------------------------------------------------------------------

AEB systems are also available on nearly all class 3 and 4 trucks
that are relatively similar in size to light trucks, are manufactured
by companies that also manufacture light vehicles, and likely have
similar component and component suppliers as light vehicles. Although
these vehicles are not required to have ESC systems, many of them are
also available with ESC, likely because these vehicles are similar in
size and use to light trucks. However, while NHTSA has information on
ESC and AEB system availability, NHTSA has no

[[Page 43201]]

information on what percentage of class 3 and 4 vehicle purchases are
equipped with ESC and AEB. For classes 5 and 6, there is substantially
lower ESC and AEB system availability. However, NHTSA believes that
this slower pace of voluntary adoption does not imply that these
vehicles are not capable of being deployed with an AEB system. The
system components are largely the same and have little to do with a
vehicle's size. There are also vehicles within these classes that are
available with ESC, and the availability of ESC has increased since
NHTSA issued FMVSS No. 136. This market information indicates that AEB
is practicable for all vehicles included in this proposal.

D. This NPRM Would Compel Improvements in AEB

This rulemaking is also needed to drive improvements in AEB
systems. The performance requirements proposed in this NPRM are
designed around the goal of realizing as much of the safety potential
of AEB systems as possible, while remaining realistic and practicable.
Some contemporary AEB systems are currently designed to detect and
mitigate collision with a vehicle ahead when travelling at a wide range
of speeds, including interstate speeds.\93\ While the systems are also
functional at lower speeds, the higher speed capabilities indicate that
AEB will be capable of reducing the frequency of interstate rear-end
crashes rather than just slower speed events.
---------------------------------------------------------------------------

\93\ See https://www.bendix.com/media/documents/technical_documentsproduct_literature/bulletins/SD-61-4963_US_005.pdf (last accessed March 1, 2023).
---------------------------------------------------------------------------

NHTSA has tentatively concluded that the improvements to AEB
systems by manufacturers in the absence of regulation have
insufficiently addressed the safety problem associated with rear-end
crashes. No individual vehicle's AEB system tested by NHTSA is
currently capable of avoiding a collision over the range of test speeds
that aligns with the majority of the safety problem. However, the range
of speeds included in this proposal is practicable as at least some
vehicles were able to achieve the desired results at each tested speed.
While manufacturers may continue to improve AEB systems, only a
regulation would ensure that all heavy vehicles are equipped with an
AEB system that can avoid a collision at a range of speeds that targets
the majority of the safety problem. Establishing performance criteria
that meet the safety need of preventing fatalities and serious injuries
will also ensure that the systems will be designed to address the
serious safety problem associated with these crashes. This NPRM
proposes that all heavy vehicles be subject to the same performance
requirements such that the entire heavy vehicle fleet benefits from
improvements in AEB technology.

E. BIL Section 23010(b)(2)(B)

NHTSA is issuing this NPRM in accordance with a statutory mandate
in BIL. Section 23010 of BIL requires the Secretary to prescribe a
Federal motor vehicle safety standard to require all commercial
vehicles subject to FMVSS No. 136 to be equipped with an AEB system.
The FMVSS is required to establish performance standards for AEB
systems. BIL directs the Secretary to prescribe the standard not later
than two years after the date of enactment of the Act.
Section 23010(b)(2)(B) of BIL states that prior to prescribing the
FMVSS for heavy vehicle AEB, the Secretary shall consult with
representatives of commercial motor vehicle drivers regarding the
experiences of drivers with AEB. Prior to this NPRM, NHTSA and FMCSA
have engaged drivers and the industry more generally in various ways.
NHTSA has published research previously that involved surveying the
driving experiences of 18 drivers driving heavy trucks equipped with a
prototype FCW system over a 10-month period in May 2011.\94\ NHTSA has
also been sponsoring studies seeking input of commercial motor vehicle
drivers. The current ongoing field study with VTTI aims to collect and
analyze performance and operational data on newer generation AEB crash
avoidance technologies on new, class 8 tractors by heavy vehicle
original equipment manufacturers and their suppliers. One year of
naturalistic driving data will be collected by monitoring the
production systems used in real-world conditions as deployed by
multiple fleets across the United States. In addition to the
performance and operational data retrieved from on-board data
acquisition systems for evaluation, the study will also involve
conducting subjective surveys with drivers and fleet managers regarding
performance, satisfaction, and overall acceptance of the crash
avoidance technologies.
---------------------------------------------------------------------------

\94\ ``Integrated Vehicle-Based Safety Systems Heavy-Truck Field
Operational Test Independent Evaluation,'' DOT HS 811 464.
---------------------------------------------------------------------------

FMSCA is also engaged consultation with representatives of drivers
through the Tech-Celerate Now program.\95\ This program intends to
accelerate the adoption of advanced crash avoidance technologies by the
trucking industry. The first phase initiatives include national
outreach and education. The outreach element allowed for the successful
creation of training materials for fleets, drivers, and maintenance
personnel related to AEB technology. Additionally, the program features
other avenues to reach drivers including educational videos on braking,
presentations, booth exhibitions, and webinars. As of January 2023,
FMCSA has compiled the findings from drivers and/or representatives of
drivers in a final report that is currently undergoing internal review.
However, planning for the second phase has been initiated and includes
expanding the national outreach and education campaign.
---------------------------------------------------------------------------

\95\ Tech-Celerate Now. FMCSA. Available at https://www.fmcsa.dot.gov/Tech-CelerateNow (last accessed August 8, 2022).
---------------------------------------------------------------------------

Building upon this and other research, NHTSA and FMCSA seek comment
from representatives of commercial motor vehicle drivers, and from
drivers themselves, about their experiences with AEB systems, including
whether the AEB system prevented a crash, whether the FCW warnings were
helpful, and whether any malfunctions or unwarranted activations
occurred. Although members of the public should comment on all aspects
of the NPRM they find relevant, NHTSA also request comments on the
following specific issues:
This proposal includes considerations that automatic
braking is needed for safety and crash prevention. NHTSA seeks comment
from driver experiences with AEB-equipped heavy vehicles on whether AEB
improves heavy vehicle rear-end crash safety.
This proposal includes warning requirements to the driver
as part of the AEB system that braking is needed in a rear-end crash-
imminent situation. NHTSA seeks comments from driver experiences on
whether AEB is helpful in getting a driver's attention back to the task
of driving.
This proposal includes requirements that automatic braking
will occur in the event of an imminent collision on a straight testing
path. NHTSA seeks comment on driver experiences with the performance of
AEB when it is applied on curved roads.
This proposal includes requirements that automatic braking
will be tested under certain weather and roadway pavement conditions.
NHTSA seeks comment on driver experiences when AEB is applied at the
last moment in all weather conditions.
This proposal includes considerations that automatic
braking is needed because of multiple elements, including driver
misjudgments and distractions. NHTSA seeks comment on driver
experiences on whether the

[[Page 43202]]

application of AEB causes drivers to pay less attention to the road; or
whether the application of AEB distracts or annoys drivers.

F. Vehicles Excluded From Braking Requirements

The result of this proposal would require AEB and ESC on nearly all
heavy vehicles. The only vehicles that would be excluded from AEB and
ESC requirements would be vehicles that are already excluded from
NHTSA's braking requirements for vehicles equipped with pneumatic
brakes in FMVSS No. 121. This braking standard includes requirements
for minimum stopping distance. For those vehicles, there is no
assurance that their foundational brake systems would have the
capability to meet the proposed AEB performance requirements, even if
equipped with sensors capable of detecting another vehicle. These
vehicles are also presently excluded from FMVSS No. 136 and would
continue to be excluded under this proposal. The vehicles excluded from
the proposed AEB and ESC requirements are:
Any vehicle equipped with an air brake system and equipped
with an axle that has a gross axle weight rating of 13,154 kilograms
(29,000 pounds) or more;
Any truck or bus that is equipped with an air brake system
and that has a speed attainable in 3.2 km (2 miles) of not more than 53
km/h (33 mph);
Any truck equipped with an air brake system that has a
speed attainable in 3.2 km (2 miles) of not more than 72 km/h (45 mph),
an unloaded vehicle weight that is not less than 95 percent of its
gross vehicle weight rating, and no capacity to carry occupants other
than the driver and operating crew.
FMCSA believes that an exemption from its ESC and AEB regulations
is appropriate for vehicles involved in driveaway-towaway operations,
for example, vehicles that are being transported to dealer locations or
that are manufactured exclusively for use outside of the United States.
Although these vehicles are operated on public roads in the United
States when they are being transported from the point of manufacture to
a domestic or foreign destination, these vehicles have not yet entered
commercial service. The economic burden associated with requiring these
vehicles to be equipped with AEB or ESC for the one-way trip out of the
United States would certainly exceed the potential benefits.
The driveaway-towaway exemption would also be applicable to
vehicles being delivered to the Armed Forces of the United States.
Vehicles operated by the military are exempt from the FMCSRs under
Sec. 390.3(f)(2).\96\
---------------------------------------------------------------------------

\96\ FMCSA notes that the driveaway-towaway exemption provided
in Sec. 393.56 and Sec. 393.57 is consistent with exceptions
provided by NHTSA. Section 571.7(c) provides an exception for
vehicles and items of equipment manufactured for, and sold directly
to, the Armed Forces of the United States in conformity with
contractual specifications. Section 571.7(d), through a cross-
reference to the United States Code, indicates the FMVSSs do not
apply to motor vehicles or motor vehicle equipment intended only for
export, labeled for export on the vehicle or equipment and on the
outside of any container of the vehicle or equipment, and exported
(49 U.S.C. 30112(b)(2)).
---------------------------------------------------------------------------

FMCSA seeks comment on other types of operations for which an
exemption from the AEB or ESC requirements may be appropriate. For
example, what types of exemptions may be needed for CMVs with auxiliary
equipment installed that would interfere with the operation of the AEB
system?

VI. Heavy Vehicles Not Currently Subject to ESC Requirements

A. AEB and ESC Are Less Available on These Vehicles

NHTSA is proposing to include nearly all vehicles with a GVWR
greater than 4,536 kg (10,000 lbs.). This includes vehicles that are
currently exempted from FMVSS No. 136 such as trucks other than truck
tractors, school buses, perimeter-seating buses, transit buses,
passenger cars, and multipurpose passenger vehicles because about half
of the fatalities and serious injuries brought about by heavy vehicles
are caused by class 3 through 6 vehicles.
The FMVSSs do not currently require ESC on class 3 through 6
vehicles or on class 7 and 8 single unit trucks, school buses, and
certain bus types such as transit buses. ESC has not been commercially
available for as long on class 3 through 6 vehicles as it has been for
class 7 and 8 vehicles. However, examples can be found of manufacturers
who offer ESC as an option on their class 3 through 6 vehicles.
Kenworth has made AEB optional for the T880 vocational truck as well as
for their T270 and T370 conventional class 6 trucks. Ford made ESC
standard on its F-650 model in the 2018 model year and has made AEB
optional on model year 2022 F-650 and F-750 class 6 trucks. A number of
school bus manufacturers have made ESC standard on certain models,
including ones that fall into classes 3 through 6. For example, Thomas
Built offers ESC as standard equipment on its type C school buses,
which can be configured to be in class 6. In some cases, ESC technology
originating in hydraulic-brake passenger cars has moved up into the
lower classes of heavy vehicles. For example, the 2019 Mercedes
Sprinter, a cargo van which can be configured as a class 3 heavy
vehicle, has ESC as standard equipment. Other class 3 and 4 vehicles
that resemble light vehicles, such as pickup trucks, are available with
ESC.
The availability of ESC as an option across multiple brands and
models within class 3 through 6 leads NHTSA tentatively to conclude
that providing ESC is technically and economically feasible. NHTSA
believes it is reasonable and practicable to require that ESC to be
installed on class 3 through 6 vehicles.

B. This NPRM Proposes To Require ESC

NHTSA has tentatively determined that ESC is necessary for safety
to include as a foundation for an AEB requirement. Historically, the
two technologies have been thought of as supplement or complementary
rather joined technologies. That is, while ESC and AEB share hardware
fundamental to both technologies, such as brake actuators, ESC is
generally not described or advertised as a component of AEB.
That said, despite this theoretical separation, in a survey NHTSA
has conducted on the availability of ESC and AEB systems, NHTSA was
unable to identify any heavy vehicle that could currently be purchased
with an AEB system, other than an FCW-only system (i.e., not capable of
automatic brake application), that did not also have an ESC system.\97\
In a 2017 white paper Bendix indicated that collision mitigation
technology is built on a foundation of full stability. Bendix stated
that as we look to more automated, autonomous functionality in the
future, all of this is likely to be built on an ESC foundation as
well.\98\ In a 2018 news release, Bendix stated that ESC provides the
necessary platform for more advanced driver assistance systems (ADAS),
including collision mitigation technologies.\99\ Manufacturers such as
Ford have ESC as a must-have system for installing driver assist
technology on the stripped commercial chassis, including AEB.\100\

[[Page 43203]]

Also, Ford has ESC and AEB as standard equipment on other chassis
models such as the E-series models, F-650, and F-750 truck series. Ram
Trucks also offers ESC and AEB for Chassis Cab models like RAM 3500
trucks.^{101 102} Based upon these factors and its own
understanding of the capabilities of AEB and ESC systems, NHTSA has
tentatively concluded that there may be safety risks associated with
the installation of an AEB system without an ESC system. For example, a
driver who responds to an imminent collision by steering to avoid a
collision while an AEB system is simultaneously applying braking may
induce a lateral instability event that is not addressed by ABS, but
that may be prevented with an ESC system. Thus, this NPRM proposes to
require both AEB and ESC for the class 3 through 8 vehicles not
currently subject to FMVSS No. 136.
---------------------------------------------------------------------------

\97\ This information is available in NHTSA's VRTC class 3 to 6
market scan for ESC-FCW-AEB spreadsheet, which has been placed in
the docket identified in the heading of this NPRM.
\98\ Full Stability and the Road Map to The Future- Are we still
on the Right Road? https://www.bendix.com/media/documents/products_1/absstability/BW8055_US_000.pdf (last accessed March 3,
2023).
\99\ October 16, 2018. Bendix News Release, ``WORKING TOGETHER,
BENDIX AND NORTH AMERICA'S SCHOOL BUS MANUFACTURERS ENHANCE STUDENT
TRANSPORTATION SAFETY''.
\100\ 2022 Ford Commercial Vehicles, F-59 Commercial Stripped
Chassis. ESC is required for the stripped chassis Driver Assist
Technology Package.
\101\ ESC equipped standard on E-Series models, and F-650/F-750
trucks, available at this link https://www.ford.com/cmslibs/content/dam/vdm_ford/live/en_us/ford/nameplate/f-650-750/2022/brochures/BRO_SUF_130E80EB-C9B2-936F-6F54-72CA6F5472CA.pdf (last viewed March
3, 2023).
\102\ https://www.ramtrucks.com/gab.html, ESC equipped standard
on the RAM Chassis cab models and RAM 3500 trucks, available at this
link (last accessed March 3, 2023).
---------------------------------------------------------------------------

NHTSA requests comment on this tentative conclusion that ESC is
necessary to ensure safe AEB operation or whether ESC systems are
necessary prerequisites for AEB systems for any other reason. NHTSA
further requests comments on specific safety scenarios where ESC
systems would be necessary for safe operation of an AEB system.
Currently, pursuant to FMVSS No. 136, only class 7 and 8 truck
tractors and certain large buses are required to have ESC systems.
FMVSS No. 136 includes both vehicle equipment requirements and
performance requirements. This proposal would require nearly all heavy
vehicles to have an ESC system that meets the equipment requirements,
general system operational capability requirements, and malfunction
detection requirements of FMVSS No. 136. The general ESC system
operational capability requirements are the nine capabilities that are
specified in the definition of ESC system in S4 of FMVSS No. 136, which
include a means to augment directional stability and enhance rollover
stability by having control over the brake systems individually at each
wheel position and the means to control engine torque. However, NHTSA
is not proposing test track performance requirements at this time
because NHTSA is conscious of the potential testing burden on small
businesses and the multi-stage vehicle manufacturers involved in class
3 through 6 vehicle production.
NHTSA's proposed approach would provide vehicle manufacturers the
ability to ascertain the ESC system design most appropriate for their
vehicles. The approach recognizes that ESC system design is dependent
on vehicle dynamics characteristics, such as the total vehicle weight
and location of that weight (center of gravity), which would differ
depending on the final vehicle configuration. Vehicles not subject to
FMVSS No. 136 include a large variety of vehicle configurations, which
can result in numerous variations of ESC system design. The approach
provides maximum flexibility to vehicle manufacturers to evaluate the
characteristics of their vehicles and design an ESC system.
In Europe, ESC was predicted to prevent about 3,000 fatalities (14
percent), and about 50,000 injuries (6 percent) per year.\103\ In
Europe, ESC has been mandatory for new types of vehicles since 2011,
and for all new vehicles is mandatory since 2014.\104\ More information
about international regulations can be found in Appendix B.
---------------------------------------------------------------------------

\103\ Iombiller, S.F., Prado, W.B., Silva M.A. (September 15,
2019). Comparative Analysis between American and European
Requirements for Electronic Stability Control (ESC) Focusing on
Commercial Vehicles. SAE International.
\104\ July 31, 2009, Official Journal of the European Union,
Regulation (EC) No. 661/2009, Articles 12 & 13, and Annex V.
---------------------------------------------------------------------------

C. BIL Section 23010(d)

Section 23010 of BIL requires the Secretary to prescribe a Federal
motor vehicle safety standard to require any commercial vehicle subject
to FMVSS No. 136, that is manufactured after the effective date of an
AEB standard, to be equipped with an AEB system that meets established
performance standards. In addition, Section 23010(d) of BIL requires
NHTSA to study equipping AEB on a variety of commercial motor vehicles
not subject to FMVSS No. 136, including an assessment of the
feasibility, benefits, and costs associated with installing AEB systems
on a variety of newly manufactured commercial motor vehicles with a
GVWR greater than 10,000 pounds. Section (d)(3) states that the
Secretary shall issue a notice in the Federal Register containing the
findings of the study and provide an opportunity for public comment.
After completion of this study, the Secretary must determine whether a
motor vehicle safety standard would meet the requirements and
considerations described in paragraphs (a) and (b) of section 30111 of
the Safety Act, and if the Secretary finds that an FMVSS would meet
such requirements, initiate a rulemaking to prescribe such an FMVSS.
This NPRM and the accompanying PRIA fulfils the mandate of section
23010(d)(1) concerning a study on equipping commercial vehicles not
subject to FMVSS No. 136 with AEB. Pursuant to the mandate section
23010(d)(3) of BIL, NHTSA seeks comment on the tentative conclusions in
this NPRM and the PRIA regarding the feasibility, benefits, and costs
associated with installing AEB on all heavy vehicles, particularly
class 3-6 vehicles and class 7 and 8 single-unit trucks. Further, as
part of this rulemaking, the agency has considered whether proceeding
with an AEB mandate for these vehicles meet the necessary provisions of
the Safety Act, and will continue to do so in any final rule. Finally,
although the agency notes that paragraph (d) concerns when the agency
would be mandated to initiate a rulemaking to require AEB for these
vehicles, that section does not affect the agency's discretionary
ability to issue an FMVSS when it believes doing so is compelled by the
Safety Act.

D. Multi-Stage Vehicle Manufacturers and Alterers

Heavy vehicles include many specialty or vocational vehicles such
as work trucks, delivery box trucks, motorhomes, and school buses, and
the complexities within this large variety of special purpose vehicles
make installation of ESC and AEB more challenging. These specialized
vehicles may be produced in lower volumes with customized features to
suit the specific needs of individual customers and in multiple stages
by several manufacturers. Concepts and terminology relating to the
certification of vehicles built in two or more stages (multi-stage
vehicles) and alters are described below.
In the typical situation, a vehicle built in two or more stages is
one in which an incomplete vehicle, such as a chassis-cab or cut-away
chassis built by one manufacturer, is completed by another manufacturer
who adds work-performing or cargo-carrying components to the vehicle.
For example, the incomplete vehicle may have a cab, but nothing built
on the frame behind the cab. As completed, it may be a dry freight van
(box truck), dump truck, tow truck, or plumber's truck. Like all
vehicles that are manufactured for sale in the United States, a multi-
stage vehicle must be certified as complying with all applicable
Federal motor

[[Page 43204]]

vehicle safety standards (FMVSS) before the vehicle is introduced into
interstate commerce.
Manufacturers involved in the production of multi-stage vehicles
can include, in addition to the incomplete vehicle manufacturer, one or
more intermediate manufacturers, who perform manufacturing operations
on the incomplete vehicle after it has left the incomplete vehicle
manufacturer's hands, and a final-stage manufacturer who completes the
vehicle so that it is capable of performing its intended function.
In some circumstances, a manufacturer at an earlier stage in the
chain of production for a multi-stage vehicle can certify that the
vehicle will comply with one or more FMVSS when completed, provided
specified conditions are met. This allows what is commonly referred to
as ``pass-through certification.'' As long as a subsequent manufacturer
meets the conditions of the prior certification, that subsequent
manufacturer may rely on this certification and pass it through when
certifying the completed vehicle.
NHTSA requests comments on how this proposal may impact multi-stage
manufacturers and alterers. The agency seeks comment on the specific
challenges that would be faced by the manufacturers in certifying to
the proposed AEB or ESC or in altering a vehicle certified to the
proposed requirements, and on whether and how NHTSA could revise this
proposal to minimize any disproportionate impact.
We believe that small-volume vehicle manufacturers are not likely
to certify compliance with the proposed AEB and ESC requirements
through their own testing but will use a combination of component
testing by brake system suppliers and engineering judgment. Already
much of the braking development work, including for ABS and ESC, for
these small-volume vehicle manufacturers is done by brake suppliers.
That is, small-volume manufacturers already must certify their vehicles
to FMVSS Nos. 136, 105, and 121. NHTSA believes that small-volume
manufacturers would certify to the proposed ESC and AEB requirements
using the means they use now to certify to those braking requirements,
which involves collaborating with their brake system suppliers, first
and second stage manufacturers, etc. This NPRM would also provide one
year after the last applicable date for manufacturer certification of
compliance, in accordance with 49 CFR 571.8(b).
NHTSA's regulations governing vehicles manufactured in two or more
stages at 49 CFR part 568 require incomplete vehicle manufacturers to
provide with each incomplete vehicle an incomplete vehicle document
(IVD). This document details, with varying degrees of specificity, the
types of future manufacturing contemplated by the incomplete vehicle
manufacturer and must provide, for each applicable safety standard, one
of the following three statements that a subsequent manufacturer can
rely on when certifying compliance of the vehicle, as finally
manufactured, to some or all of all applicable FMVSS.
First, the IVD may state, with respect to a particular safety
standard, that the vehicle, when completed, will conform to the
standard if no alterations are made in identified components of the
incomplete vehicle. This representation, which is referred to as a
``Type 1 statement,'' is most often made with respect to chassis-cabs,
since a significant portion of the occupant compartment in incomplete
vehicles of that type is already complete.
Second, the IVD may provide a statement of specific conditions of
final manufacture under which the completed vehicle will conform to a
particular standard or set of standards. This statement, which is
referred to as a ``Type 2 statement,'' is applicable in those instances
in which the incomplete vehicle manufacturer has provided all or a
portion of the equipment needed to comply with the standard, but
subsequent manufacturing might be expected to change the vehicle such
that it may not comply with the standard once finally manufactured. For
example, the incomplete vehicle could be equipped with a brake system
that would, in many instances, enable the vehicle to comply with the
applicable brake standard once the vehicle was complete, but that would
not enable it to comply if the completed vehicle's weight or center of
gravity height were altered from those specified in the IVD.
Third, the IVD may identify those standards for which no
representation of conformity is made because conformity with the
standard is not substantially affected by the design of the incomplete
vehicle. This is referred to as a ``Type 3 statement.'' A statement of
this kind could be made, for example, by a manufacturer of a stripped
chassis who may be unable to make any representations about conformity
to any crashworthiness standards if the incomplete vehicle does not
contain an occupant compartment. When it issued the original set of
regulations regarding certification of vehicles built in two or more
stages, the agency indicated that it believed final-stage manufacturers
would be able to rely on the representations made in the IVDs when
certifying the completed vehicle's compliance with all applicable
FMVSS.
Although the final-stage manufacturer normally certifies the
completed vehicle's compliance with all applicable FMVSS, this
responsibility can be assumed by any other manufacturer in the
production chain. To take on this responsibility, the other
manufacturer must ensure that it is identified as the vehicle
manufacturer on the certification label that is permanently affixed to
the vehicle. The identified manufacturer also has legal responsibility
to provide NHTSA and vehicle owners with notification of any defect
related to motor vehicle safety or noncompliance with an FMVSS that is
found to exist in the vehicle, and to remedy any such defect or
noncompliance without charge to the vehicle's owner.
An altered vehicle is one that is completed and certified in
accordance with the agency's regulations and then altered, other than
by the addition, substitution, or removal of readily attachable
components, such as mirrors or tire and rim assemblies, or by minor
finishing operations such as painting, before the first retail sale of
the vehicle, in such a manner as may affect the vehicle's compliance
with one or more FMVSS or the validity of the vehicle's stated weight
ratings or vehicle type classification. The person who performs such
operations on a completed vehicle is referred to as a vehicle
``alterer.'' An alterer must certify that the vehicle remains in
compliance with all applicable FMVSS affected by the alteration.
NHTSA seeks comment on the impacts of this NPRM on multi-stage
manufacturers and alterers and requests comments on the following
questions.
Are certain multi-stage or altered vehicles manufactured
or altered in a manner that makes it impracticable to comply with this
proposed rule? If so, please explain which vehicles and why it is
impracticable.
If an incomplete vehicle were equipped with sensors for
AEB that could become obstructed by equipment added in later
manufacturing steps, how should NHTSA apply an AEB requirement to that
vehicle?
Are there any changes needed to 49 CFR part 567 or part
568 to facilitate certification to the proposed requirements? If so,
what would those changes be? Would a final-stage manufacturer be able
to certify a vehicle based on the information provided by an
intermediate or incomplete vehicle manufacturer, or is additional
information needed in IVDs? If

[[Page 43205]]

additional information is needed, please describe the needed
information.
Are there any requirements in this proposal that ought not
to apply to multi-stage vehicles or altered vehicles? Are there
proposed requirements that should be lowered in stringency to better
enable pass-through certification? Please provide details on those
requirements and provide associated rationale.
Would intermediate manufacturers, final-stage
manufacturers, and alterers have sufficient information to identify
when an impermissible change has been made? Please explain why or why
not.
Assuming there would be cases where it may not be
practical to comply with the proposed requirements, are the existing
exemption processes detailed in 49 CFR 555, ``Temporary exemption from
motor vehicle safety and bumper standards,'' sufficient to accommodate
unique vehicles, or should NHTSA explicitly consider applicability
exclusions for certain multi-stage vehicles? If applicability
exclusions are needed, please explain what they include and why the
exclusion is needed. For example, should there be exclusions for
vehicles with permanently installed work-performing equipment installed
on the front of or extending past the front of the vehicle (e.g., auger
trucks, bucket trucks, cable reel trucks, certain car carriers, etc.)
or vehicles with a GVWR equal to or greater than 120,000 pounds (i.e.,
heavy haulers)?

VII. Proposed Performance Requirements

This NPRM proposes that all heavy vehicles, class 3-8, are subject
to the same performance requirements such that the entire heavy vehicle
fleet benefits from improvements in AEB technology. The proposed set of
requirements would compel AEB technology to operate at its highest
safety potential, while at the same time being objective and
practicable. In order to establish these requirements, the agency
considered the key aspects of the technology and how they would best be
applied to address the safety problem. For example, requiring AEB
systems to perform only at lower speeds may address a significant
portion of the rear-end crash problem, but it would not address the
rear-end crash fatalities that mostly occur at higher speeds. Thus,
NHTSA is proposing that AEB systems must be capable of activating
across a wide spectrum of speeds. Similarly, the agency is aware that
some current AEB systems may occasionally cause unwarranted braking
events, or ``false activations,'' which could lead to unwanted
consequences; we are thus proposing two test scenarios which vehicles
must pass without false activation of the AEB system.
While creating the proposed performance requirements, NHTSA
considered the capabilities and limitations of current AEB
technologies. Using information from vehicle testing, this proposal
includes test scenarios and parameters that the agency found to be
within the potential of current production vehicles. This means that at
least one vehicle model demonstrated the ability to avoid impacting a
lead vehicle, represented by a vehicle test device, or that it so
nearly avoided the impact that we expect that the additional
development time allowed by this proposal would enable the required
improvement in performance.
While certain requirements can be assessed without vehicle tests, a
large portion of this proposal has performance requirements that are
evaluated through vehicle tests. These tests, discussed in this
section, simulate real-world scenarios and are run according to
specified conditions and test parameters. NHTSA believes that these
test scenarios will realistically evaluate how AEB systems perform
while the vehicle is travelling at normal driving speeds.
Several of the vehicle test scenarios test involve multiple moving
vehicles. In these test scenarios, the heavy vehicle being evaluated
with AEB is referred to as the ``subject vehicle.'' Other vehicles
involved in the test are represented by a vehicle test device. When a
vehicle test device is used ahead of the subject vehicle in the same
lane, in the path of the moving subject vehicle, it is referred to as a
``lead vehicle.'' When moving, a lead vehicle moves in the same
direction as the subject vehicle. The speeds and relative motions of
the subject vehicle and lead vehicle are choreographed in a variety of
ways to represent the most common scenarios which lead to heavy vehicle
rear-end crashes, and the test procedures measure whether the AEB
system is able to avoid impacting the lead vehicle.
The other vehicle tests are two false activation scenarios. A false
activation refers to an unwarranted brake activation by the AEB system
when there is no object present in the path of the vehicle with which
the vehicle would collide. These two test scenarios use objects,
including VTDs and a steel trench plate, arranged in realistic ways in
or near the travel path but without obstructing the path. In these
scenarios, the subject vehicle and AEB system are required to move past
these objects without making a substantial automatic application of the
service brakes.
This proposal also includes system requirements that are not
accompanied by vehicle tests. Vehicles with AEB systems must mitigate
collision at speeds beyond the those covered by the track testing,
ensuring robustness of the system's range of performance. The AEB
system must include a forward collision warning (FCW) system that
alerts the vehicle operator of an impending collision with a lead
vehicle. Also, the system must indicate an AEB malfunction to the
vehicle operator.

A. Proposed Requirements When Approaching a Lead Vehicle

1. Automatic Emergency Brake Application Requirements
The agency is proposing that vehicles be required to have a forward
collision warning system and an automatic emergency braking system that
are able to function continuously to apply the service brakes
automatically when a collision with a vehicle or object is imminent.
The system must operate when the vehicle is traveling at any forward
speed greater than 10 km/h (6.2 mph). This is a general system
equipment requirement with no associated performance test. No specific
speed reduction or crash avoidance would be required. However, this
requirement is included to ensure that AEB systems are able to function
at all times, including at speeds above those NHTSA is proposing as
part of the performance test requirements.
This requirement complements the performance requirements in
several ways. While the track testing described below provides a
representation of real-world crash events, no amount of track testing
can fully duplicate the real world. This requirement ensures that the
AEB's perception system identifies and automatically detects a vehicle,
warns the driver, and applies braking when a collision is imminent.
This requirement also ensures that AEB systems continue to function in
environments that are not as controlled as the test track environment.
For example, unlike during track testing, other vehicles, road users,
and buildings may be present within the view of the sensors. Finally,
track test equipment limitations and safety considerations limit the
ability to test at high speeds. However, crashes still occur at higher
travel speeds. Although generally the number of rear-end crashes
decreases at higher travel speeds, these high-speed crashes are the
ones that more often result in fatalities, as shown in Figure 3. The
automatic braking requirement

[[Page 43206]]

ensures that AEB systems continue to provide safety benefits at speeds
above those for which a track-testing requirement is currently not
practicable, either because of performance capabilities or track test
limitations. Where a performance standard is not practical or does not
sufficiently meet the need for safety, NHTSA may specify an equipment
requirement as part of an FMVSS.\105\
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\105\ See 72 FR 17235, 17299 (Apr. 6, 2007) (discussing the
understeer requirement in FMVSS No. 126); Chrysler Corp. v. DOT, 515
F.2d 1053 (6th Cir. 1975) (holding that NHTSA's specification of
dimensional requirements for rectangular headlamps constitutes an
objective performance standard under the Safety Act).
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These requirements would not apply at speeds below 10 km/h. NHTSA
believes that there are real-world cases where heavy vehicles are being
maneuvered at low-speed and intentionally in proximity of other
objects, and AEB intervention could be in conflict with the vehicle
operator's intention. For example, if an operator intends to drive
towards the rear of another vehicle in a parking lot in order to park
the vehicle near the other, automatic braking during this parking
maneuver would be unwanted. Publicly available literature from at least
one AEB manufacturer shows that some or all of the AEB system functions
are not available below 15 mph (24 km/h), indicating that current
manufacturers may have similar considerations about low-speed AEB
functionality.\106\ NHTSA tentatively concludes that a minimum
operational speed of 10 km/h would allow these types of low-speed
maneuvers. This proposal would not require AEB systems to be disabled
below 10 km/h.
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\106\ SD-61-4963 Bendix Wingman Fusion Driver Assistance System
Brochure, available at https://www.bendix.com/media/documents/technical_documentsproduct_literature/bulletins/SD-61-4963_US_005.pdf (last accessed June 21, 2023).
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Enforcement of such a performance requirement can be based on
evidence obtained by engineering investigation that might include a
post-crash investigation and/or system design investigation. For
instance, if a crash occurs in which the vehicle under examination has
collided with a lead vehicle, NHTSA could investigate the details
surrounding the crash to determine if a warning was provided and the
automatic emergency braking system applied the service brakes
automatically. In appropriate cases in the context of an enforcement
proceeding, NHTSA could also use its information-gathering authority to
obtain information from a manufacturer on the basis for its
certification that its FCW and AEB systems meet this proposed
requirement.
2. Forward Collision Warning Requirement
NHTSA is proposing that AEB-equipped vehicles must have forward
collision warning functionality that provides a warning to the vehicle
operator if a forward collision with a lead vehicle is imminent. The
proposal defines FCW as an auditory and visual warning provided to the
vehicle operator that is designed to elicit an immediate crash
avoidance response by the vehicle operator. The system must operate
when the vehicle is traveling at any forward speed greater than 10 km/h
(6.2 mph).
While some vehicles are equipped with alerts that precede the FCW
and research has examined their use, NHTSA's proposal is not specifying
an advisory or preliminary alert that would

[[Page 43207]]

precede the FCW. Lerner, Kotwal, Lyons, and Gardner-Bonneau (1996b)
differentiated between an imminent alert, which ``requires an immediate
corrective action'' and a cautionary alert, which ``alerts the operator
to a situation which requires immediate attention and may require a
corrective action.'' \107\ A 2004 NHTSA report titled ``Safety Vehicles
using adaptive Interface Technology (Task 9): A Literature Review of
Safety Warning Countermeasures,'' examined the question of whether to
include a cautionary alert level in an FCW system. Although the two FCW
algorithms in the Automotive Collision Avoidance System Field
Operational Test algorithms included a cautionary phase, the Collision
Avoidance Metrics Partnership (1999) program recommended that only
single (imminent) stage warnings be used.
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\107\ Lerner, Kotwal, Lyons, and Gardner-Bonneau (1996).
Preliminary Human Factors Guidelines for Crash Avoidance Warning
Devices. DOT HS 808 342. National Highway Traffic Safety
Administration.
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Unlike the FCW required as part of the track testing, NHTSA is not
specifically requiring that FCW presentation occur prior to the onset
of braking in instances that are not tested on the track. This is to
provide manufacturers with the flexibility to design systems that are
most appropriate for the complexities of various crash situations, some
of which may provide very little time for a driver to take action to
avoid a crash. A requirement that FCW occur prior to automatic braking
could suppress the automatic braking function in some actual driving
scenarios, such as a lead vehicle cutting immediately in front of an
AEB-equipped vehicle, where immediate automatic braking should not wait
for a driver warning.
i. FCW Modalities
Since approximately 1994, NHTSA has completed research and
published related reports for more than 35 research efforts related to
crash avoidance warnings or forward collision warnings. These research
efforts, along with other published research and existing ISO standards
(15623 and 22839) and SAE International (SAE) documents (J3029 and
J2400) provide a basis for the proposed requirements.\108\
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\108\ ISO 15623--Forward vehicle collision warning systems--
Performance requirements and test procedures; ISO 22839--Forward
vehicle collision mitigation systems--Operation, performance, and
verification requirements (applies to light and heavy vehicles); SAE
J3029: Forward Collision Warning and Mitigation Vehicle Test
Procedure and Minimum Performance Requirements--Truck and Bus (2015-
10; WIP currently); SAE J2400 2003-08 (Information report). Human
Factors in Forward Collision Warning Systems: Operating
Characteristics and User Interface Requirements.
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NHTSA NCAP and Euro NCAP information relating to FCW was also
considered. Since model year 2011, the agency has included FCW as a
recommended technology in NCAP and identifies to consumers which light
vehicles have FCW systems that meet NCAP's performance tests. NHTSA's
March 2022 request for comments notice on proposed changes to NCAP
sought comment on which FCW modalities or modality combinations should
be necessary to receive NHTSA's NCAP recommendation.\109\ Commenters
generally supported the use of a multimodal FCW strategy. The Alliance
for Automotive Innovation and Intel both advocated allowing credit for
any effective FCW signal type. Multiple commenters supported allowing
NCAP credit for FCW having either auditory or haptic signals. BMW and
Stellantis supported use of FCW auditory or haptic signals in addition
to a visual signal. NTSB and Advocates for Highway and Auto Safety
recommended that NHTSA conduct research examining the human-machine
interface and examine the effectiveness of haptic warning signals
presented in different locations (e.g., seat belt, seat pan, brake
pulse). Dynamic Research, Inc. advocated allowing NCAP credit for
implementation of a FCW haptic brake pulse, while ZF supported use of a
haptic signal presented via the seat belt. Bosch warned that use of a
haptic signal presented via the steering wheel for lane keeping or
blind spot warning and FCW should be avoided as it may confuse the
driver. The Alliance for Automotive Innovation raised the potential
benefits of standardizing the warning characteristics to improve
effectiveness as individuals move from vehicle to vehicle.
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\109\ 87 FR 13452 (Mar. 9, 2022).
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All current U.S. vehicle models with FCW systems appear to provide
auditory and visual FCW signals, while only a few manufacturers also
provide a haptic signal (e.g., seat pan vibration or a brake pulse).
Visual FCW signals in current models consist of either a symbol or word
(e.g., ``BRAKE!''), presented on the instrument panel or head-up
display, and most are red.
For this NPRM, NHTSA proposes that the FCW be presented to the
vehicle operator via at least two sensory modalities, auditory and
visual. Use of a multimodal warning ensures that most drivers will
perceive the warning as soon as its presented, allowing the most time
for the driver to take evasive action to avoid a crash. As a vehicle
operator who is not looking toward the location of a visual warning at
the time it is presented may not see it, NHTSA's proposal views the
auditory warning signal as the primary modality and the visual signal
as a secondary, confirmatory indication that explains to the driver
what the warning was intended to communicate (i.e., a forward crash-
imminent situation). However, because hearing-impaired drivers may not
perceive an FCW auditory signal, a visual signal is important for
presenting the FCW to hearing-impaired individuals.
A multimodal FCW strategy is consistent with recommendations of
multiple U.S. and international organizations including ISO, SAE
International, and Euro NCAP. ISO recommends a multimodal approach in
both ISO 15623, ``Forward vehicle collision warning systems--
Performance requirements and test procedures'' and ISO 22839, ``Forward
vehicle collision mitigation systems--Operation, performance, and
verification requirements'' (which applies to light and heavy
vehicles). SAE addresses the topic of a multimodal FCW strategy in both
information report J2400 2003-08, ``Human Factors in Forward Collision
Warning Systems: Operating Characteristics and User Interface
Requirements,'' and J3029, ``Forward Collision Warning and Mitigation
Vehicle Test Procedure and Minimum Performance Requirements--Truck and
Bus (2015-10; Work in Progress currently).'' Most of these
recommendations specify an FCW consisting of auditory and visual
signals, while ISO 15623 specifies that an FCW include a visual
warning, as well as an auditory or haptic signal.
ii. FCW Auditory Signal Characteristics
The proposed FCW auditory signal would be the primary means used to
direct the vehicle operator's attention to the forward roadway and
should be designed to be conspicuous to quickly capture the driver's
attention, convey a high level of urgency, and be discriminable from
other auditory signals presented within the vehicle.\110\ Some
specifications from NHTSA's ``Human Factors Design Guidance For
Driver--Vehicle Interfaces'' are proposed as forward collision warning
specifications to meet these criteria.\111\

[[Page 43208]]

As the FCW auditory signal would be the primary warning mode, this
signal would not be permitted to be disabled.
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\110\ DOT HS 810 697, Crash Warning System Interfaces: Human
Factors Insights and Lessons Learned--Final Report.
\111\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
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To be conspicuous and quickly capture the driver's attention, the
FCW auditory signal must ensure that the driver will readily detect the
warning under typical driving conditions (e.g., ambient noise). The
auditory signal must be clearly perceptible and quickly focus the
driver's attention on the forward roadway. To ensure that the FCW
auditory signal is conspicuous to the vehicle operator, any in-vehicle
system or device that produces sound that may conflict with the FCW
presentation would be required to be muted, or substantially reduced in
volume, during the presentation of the FCW.\112\ In order for the
warning to be detectable, a minimum intensity of 15-30 dB above the
masked threshold (MT) should be used.^{113 114 115 116} Because
sound levels inside a vehicle can vary based on any number of different
factors, such as vehicle speed and pavement condition, NHTSA is not
proposing a specific sound level at this time, but requests comments on
suitable and reasonable approaches for ensuring that the FCW auditory
signal can be detected by drivers under typical driving conditions.
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\112\ DOT HS 810 697, Crash Warning System Interfaces: Human
Factors Insights and Lessons Learned--Final Report.
\113\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration. ``The amplitude of auditory signals is in the range
of 10-30 dB above the masked threshold (MT), with a recommended
minimum level of 15 dB above the MT (e.g., [1, 2, 3]).
Alternatively, the signal is at least 15 dB above the ambient noise
[3].''
\114\ Campbell, J.L., Richman, J.B., Carney, C., and Lee, J.D.
(2002). In-vehicle display icons and other information elements.
Task F: Final in-vehicle symbol guidelines (FHWA-RD-03-065).
Washington, DC: Federal Highway Administration.
\115\ International Organization for Standardization. (2005).
Road vehicles--Ergonomic aspects of in-vehicle presentation for
transport information and control systems--Warning systems (ISO/TR
16532). Geneva, Switzerland: International Organization of
Standards.
\116\ MIL-STD-1472F. (1998). Human engineering. Washington, DC:
Department of Defense.
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For communicating urgency and ensuring comprehension of auditory
messages, fundamental frequency, the lowest frequency in a periodic
signal, is a key design parameter.\117\ Research has shown that
auditory warning signals with a high fundamental frequency of at least
800 Hz more effectively communicate urgency.^{118 119} Greater
perceived urgency of a warning is associated with faster reaction
times, which would mean a quicker crash avoidance response by the
driver.^{120 121 122} Therefore, NHTSA proposes that the FCW
auditory signal's fundamental frequency must be at least 800 Hz.\123\
Additional proposed FCW auditory signal requirements that support
communication of the urgency of the situation include a duty
cycle,\124\ or percentage of time sound is present, of 0.25-0.95, and
faster auditory signals with a tempo in the range of 6-12 pulses per
second to be perceived as urgent and elicit rapid driver response.\125\
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\117\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
\118\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
\119\ Guilluame, A., Drake, C., Rivenez, M., Pellieux, L., &
Chastres, V. (2002). Perception of urgency and alarm design.
Proceedings of the 8th International Conference on Auditory Display.
\120\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
\121\ Campbell, J.L., Richman, J.B., Carney, C., & Lee, J.D.
(2004). In-vehicle display icons and other information elements,
Volume I: Guidelines (Report No. FHWA-RD-03-065). Washington, DC:
Federal Highway Administration. Available at www.fhwa.dot.gov/publications/research/safety/03065/index.cfm.
\122\ Suied, C., Susini, P., & McAdams, S. (2008). Evaluating
warning sound urgency with reaction times. Journal of Experimental
Psychology: Applied, 14(3), 201-212.
\123\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
\124\ Duty cycle, or percentage of time sound is present, is
equal to the total pulse duration divided by the sum of the total
pulse duration and the sum of the inter-pulse intervals.
\125\ Gonzalez, C., Lewis, B.A., Roberts, D.M., Pratt, S.M., &
Baldwin, C.L. (2012). Perceived urgency and annoyance of auditory
alerts in a driving context. Proceedings of the Human Factors and
Ergonomics Society Annual Meeting, 56(1), 1684-1687.
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The FCW auditory signal needs to be easily discriminable from other
auditory signals in the vehicle. Therefore, vehicles equipped with more
than one crash warning type should use FCW auditory signals that are
distinguishable from other warnings.\126\ This proposed requirement is
consistent with ISO 15623 5.5.2.6.\127\ Standardization of FCW auditory
signals would likely be beneficial in ensuring driver comprehension of
the warning condition across vehicle makes and models. NHTSA invites
comments on the feasibility of specifying a common FCW auditory signal.
While this proposal contains no specific requirements ensuring that the
FCW auditory signal is distinguishable from other auditory warnings in
the vehicles, NHTSA believes that industry is likely to consider this
in their vehicle designs as part of their due diligence and safety
assurance.
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\126\ DOT HS 810 697, Crash Warning System Interfaces: Human
Factors Insights and Lessons Learned--Final Report.
\127\ ISO 15623--Forward vehicle collision warning systems--
Performance requirements and test procedures.
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iii. FCW Visual Signal Characteristics
Current FCWs in the U.S. vehicle fleet use a mix of symbols and
words as a visual forward collision warning. Use of a common FCW symbol
across makes and models would help to improve consumer understanding of
the meaning of FCWs and encourage more appropriate driver responses in
forward crash-imminent situations.
ISO 7000, ``Graphical symbols for use on equipment--Registered
symbols'' \128\ and the SAE J2400 (2003-08) \129\ information report,
``Human Factors in Forward Collision Warning Systems: Operating
Characteristics and User Interface Requirements,'' contain recommended
FCW symbols shown in Figure 4. These symbols are similar as they both
communicate a forward impact, while the ISO symbol portrays the forward
impact as being specifically with another vehicle.
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\128\ ISO 7000--Graphical symbols for use on equipment--
Registered symbols.
\129\ SAE J2400 (info. report, not RP or standard), 2003-08.
Human Factors in Forward Collision Warning Systems: Operating
Characteristics and User Interface Requirements.

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Because the symbol in SAE J2400 relates the idea of a frontal crash
without depicting a particular forward object, this symbol could
visually represent and apply to scenarios when approaching a lead
vehicle but also scenarios approaching pedestrians or other objects
which may be relevant to AEB systems. To prevent different vehicle
types from having different FCW alerts, NHTSA proposes the same FCW
characteristics and reasoning in both the light vehicle NPRM and this
NPRM. Therefore, NHTSA has taken account of considerations for
pedestrian scenarios, because the light vehicle proposed rule contains
a requirement that FCW and AEB systems function in the case of an
imminent collision with a pedestrian. NHTSA finds the SAE J2400 symbol
to be most applicable to the FCW requirements in this proposal. NHTSA
proposes that FCW visual signals using a symbol must use the SAE J2400
(2003-08) symbol.
Some other vehicle models employ a word-based visual warning, such
as ``STOP!'' or ``BRAKE!'' SAE J2400 also includes a word-based visual
warning recommendation consisting of the word, ``WARNING.'' A well-
designed warning should instruct people about what to do or what not to
do to avoid a hazard. The potential benefit of a word-based warning for
FCW is that it can communicate to the driver an instruction about what
to do to avoid or mitigate the crash, thereby expediting the driver's
initiation of an appropriate crash avoidance response. However,
Consumer Reports noted in its online ``Guide to forward collision
warning'' that for some models, visual warning word use was found to be
confusing to some drivers surveyed.\130\ Respondents reported a common
complaint that ``their vehicle would issue a visual ``BRAKE'' alert on
the dash, but it wouldn't bring the car to a stop . . .'' This
confusion as to whether the word is meant to communicate what the
driver should do or what the vehicle is doing may stem from drivers
assuming that any information presented within the instrument panel
area is communicating something relating to the vehicle's condition or
state, as symbols presented in that location generally do. Presenting a
word-based warning in a higher location away from the instrument panel,
as recommended by SAE J2400, may be interpreted more accurately by
drivers as well as increase the likelihood of FCW visual warning
perception by drivers.\131\ NHTSA requests comments on this issue and
any available objective research data that relates to the effectiveness
of word-based FCW visual signals in instrument panel versus head-up
display locations. NHTSA also requests comments regarding whether
permitting word-based warnings that are customizable in terms of
language settings is necessary to ensure warning comprehension by all
drivers.
---------------------------------------------------------------------------

\130\ ``Guide to forward collision warning: How FCW helps
drivers avoid accidents.'' Consumer Reports. https://www.consumerreports.org/car-safety/forward-collision-warning-guide/
(last accessed April 2022).
\131\ SAE J2400 2003-08 (Information report). Human Factors in
Forward Collision Warning Systems: Operating Characteristics and
User Interface Requirements.
---------------------------------------------------------------------------

One plausible benefit of a word-based visual warning is that some
word choices that instruct the driver to initiate a particular action,
such as ``STOP!,'' would be fully applicable to lead vehicles and other
obstacles or pedestrians, whereas a symbol containing an image of a
lead vehicle would not be directly applicable to other crash-imminent
scenarios. Although this NPRM does not propose requiring pedestrian
AEB, NHTSA believes the warning should not be directed specifically at
lead vehicle AEB. As the response desired from the driver, to apply the
brakes, the content of the visual warning need not be specific to the
type of forward obstacle, but needs simply to communicate the idea of
an impending forward crash. NHTSA requests comments and any available
research data regarding the use and effectiveness of obstacle-specific
symbols and word-based visual warnings and the relative effectiveness
of word-based visual warnings compared to symbols.
While many current vehicle models present a visual FCW signal
within the instrument panel, drawing a driver's eyes downward away from
the roadway to the instrument panel during a forward crash-imminent
situation is likely to have a negative impact on the effectiveness of
the driver's response to the FCW. Research indicates that a visual FCW
signal presented in the instrument panel can slow driver response.\132\
The research findings support the SAE J2400 recommendation advising
against the use of instrument panel based visual FCWs.\133\ SAE J2400
(2003-08) states:
---------------------------------------------------------------------------

\132\ ``Evaluation of Forward Collision Warning System Visual
Alert Candidates and SAE J2400,'' SAE Paper No. 2009-01-0547,
https://trid.trb.org/view/1430473.
\133\ SAE J2400 2003-08 (Information report). Human Factors in
Forward Collision Warning Systems: Operating Characteristics and
User Interface Requirements.

Visual warnings shall be located within a 10-degree cone of the
driver's line of sight. Qualitatively, this generally implies a top-
of-dashboard or head-up display location. A conventional dashboard
location shall not be used for the visual warning. The rationale for
this is based on the possibility that an instrument panel-based
---------------------------------------------------------------------------
visual warning may distract the driver from the hazard ahead.

This FCW visual signal location guidance is also consistent with
ISO 15623, which states that the FCW visual signal shall be presented
in the ``main glance direction.'' Current vehicles equipped with head-
up displays have the ability to present a FCW visual signal within the
driver's forward field of view. Furthermore, some GM vehicles not
equipped with head-up displays currently have the ability to present a
FCW visual signal reflected onto the

[[Page 43210]]

windshield in the driver's forward line-of-sight. Despite the FCW
visual signal being considered secondary to the auditory signal, NHTSA
agrees that the effectiveness of a FCW visual signal would be maximized
for both hearing and hearing-impaired drivers if the signal is
presented at a location within the driver's forward field of view above
the instrument panel. To ensure maximum conspicuity of the FCW visual
signal (be it word-based or a symbol), NHTSA proposes that it be
presented within a 10-degree cone of the driver's line of sight. The
line of sight would be based on the forward-looking eye midpoint
(Mf) as described in FMVSS No. 111, ``Rear visibility,''
S14.1.5.
The FCW visual signal would be required to be red as is generally
used to communicate a dangerous condition and as recommended by ISO
15623 and SAE J2400 (2003-08). Because the FCW visual signal is
intended to be confirmatory for the majority of drivers, the symbol
would be required to be steady burning.
iv. FCW Haptic Signal Discussion
NHTSA considered also specifying a complementary haptic FCW signal
as part of the proposed FCW specifications. Currently, only a portion
of U.S. vehicles equipped with forward collision warning include a
haptic warning component. For example, General Motors vehicles equipped
with the haptic warning feature can present either a haptic seat pulse
(vibration) or auditory warning based on a driver-selectable setting.
Some other vehicle manufacturers, such as Stellantis and Audi, use a
brake pulse, or brief deceleration of the vehicle, as part of the FCW.
Some Hyundai/Kia models incorporate a haptic steering wheel vibration
into the FCW. As haptic steering wheel signals are used by many lane
keeping features of current vehicles to encourage drivers to steer the
vehicle back toward the center of the lane, providing a haptic FCW
signal via the steering wheel may result in driver confusion and be
less effective in eliciting a timely and beneficial driver response.
ISO 15623 allows a haptic signal as an alternative to an auditory
signal.\134\ It permits a haptic brake pulse warning with a duration of
less than 1 second when the driver is not already applying the brakes.
ISO 15623 also allows actuation of a seat belt pretensioner as a haptic
FCW signal.
---------------------------------------------------------------------------

\134\ ISO 15623--Forward vehicle collision warning systems--
Performance requirements and test procedures.
---------------------------------------------------------------------------

Some research has shown that haptic FCW signals can improve crash
avoidance response. NHTSA research on ``Driver-Vehicle Interfaces for
Advanced Crash Warning Systems'' found that a haptic signal delivered
via the seat belt pretensioner would be beneficial in eliciting an
effective crash avoidance response from the vehicle operator. The
research showed for FCWs issued at 2.1-s time to collision (TTC) that
seat belt pretensioner-based FCW signals elicited the most effective
crash avoidance performance.\135\ Haptic FCW signals led to faster
driver response times than did auditory tonal signals. FCW modality had
a significant effect on participant reaction times and on the speed
reductions resulting from participants' avoidance maneuvers (regardless
of whether a collision ultimately occurred). Brake pulsing or seat belt
tensioning were found to be effective for returning distracted drivers'
attention to the forward roadway and eliciting desirable vehicle
control responses; seat vibration similar to a virtual rumble strip
(vibrating the front of the seat) was not found to rapidly and reliably
return driver attention to the forward roadway within the research.
Similarly, research by Aust (2014) found that ``combining sound with
seat belt jerks or a brake pulse leads to significantly faster response
times than combining the sound with a visual warning'' and stated,
``these results suggest that future FCWs should include a haptic
modality to improve driver performance.'' \136\ Aust (2014) also found
use of a haptic seat belt FCW signal to be slightly more effective (100
ms faster driver response) than a haptic brake pulse in one of two
scenarios (response times were equal in a second scenario). Despite
these promising research results associated with use of a seat belt
based FCW haptic component, NHTSA was unable to identify any current
U.S. vehicle models equipped with a haptic seat belt FCW component.
---------------------------------------------------------------------------

\135\ Lerner, N., Singer, J., Huey, R., Brown, T., Marshall, D.,
Chrysler, S., . . . & Chiang, D.P. (2015, November). Driver-vehicle
interfaces for advanced crash warning systems: Research on
evaluation methods and warning signals. (Report No. DOT HS 812 208).
Washington, DC: National Highway Traffic Safety Administration.
\136\ Aust, M. (2014) Effects of Haptic Versus Visual Modalities
When Combined With Sound in Forward Collision Warnings. Driving
Simulation Conference 2014, Paper number 36. Paris, France,
September 4-5, 2014.
---------------------------------------------------------------------------

Other studies found FCW haptic brake pulses effective at getting a
driver's attention and that drivers are more likely to detect a brake
pulse if it produces a sensation of ``jerk'' or ``self-motion.''
^{137 138} Kolke reported reaction times shortened by one-third
(approximately 0.3 s, non-significant) when a brake pulse was added to
an audio-visual warning.\139\ One usability drawback is that drivers
tend to report that vehicle brake pulses are too disruptive, which can
lead to unfavorable annoyance.\140\
---------------------------------------------------------------------------

\137\ Lee, J.D., McGehee, D.V., Brown, T.L., & Nakamoto, J.
(2012). Driver sensitivity to brake pulse duration and magnitude.
Ergonomics, 50(6), 828-836.
\138\ Brown, S.B., Lee, S.E., Perez, M.A., Doerzaph, Z.R.,
Neale, V.L., & Dingus, T.A. (2005). Effects of haptic brake pulse
warnings on driver behavior during an intersection approach.
Proceedings of the Human Factors and Ergonomics Society 49th Annual
Meeting, 1892-1896.
\139\ Kolke, Gauss, and Silvestro (2012). Accident reduction
through emergency braking systems in passenger cars. Presentation at
the 8th ADAC/BASt-Symposium ``Driving Safely in Europe.'' October 5,
2012, Workshop B.
\140\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
---------------------------------------------------------------------------

Presentation of a FCW haptic signal via the driver's seat pan has
also been investigated. NHTSA's ``Human factors design guidance for
driver-vehicle interfaces'' contains best practice information for
implementation of haptic displays, including ``Generating a Detectable
Signal in a Vibrotactile Seat.'' \141\ In a large-scale field test of
FCW and LDW systems on model year 2013 Chevrolet and Cadillac vehicles,
the University of Michigan Transportation Research Institute and GM
found that GM's Safety Alert Seat, which provides haptic seat vibration
pulses, increases driver acceptance of both FCW and LDW systems
compared to auditory signals.\142\
---------------------------------------------------------------------------

\141\ Campbell, J.L., Brown. J.L., Graving, J.S., Richard, C.M.,
Lichty, M.G., Sanquist, T., . . . & Morgan, J.L. (2016, December).
Human factors design guidance for driver-vehicle interfaces (Report
No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety
Administration.
\142\ Flannagan, C., LeBlanc, D., Bogard, S., Nobukawa, K.,
Narayanaswamy, P., Leslie, A., Kiefer, R., Marchione, M., Beck, C.,
and Lobes, K. (2016, February), Large-scale field test of forward
collision alert and lane departure warning systems (Report No. DOT
HS 812 247), Washington, DC: National Highway Traffic Safety
Administration.
---------------------------------------------------------------------------

NHTSA's March 2022 request for comments notice on the NCAP sought
comment on which FCW modalities or modality combinations should receive
credit and asked specific questions regarding haptic signals and
whether certain types should be excluded from consideration (e.g.,
because they may be such a nuisance to drivers that they are more
likely to disable the FCW or AEB system). A preliminary review of
comments on that notice found multiple comments highlighting a need for
more

[[Page 43211]]

research relating to FCW signals. The National Transportation Safety
Board highlighted a need for additional information regarding haptic
signals presented in different locations stating ``[w]ithout examining
the efficacy of different means of providing haptic alerts and defining
appropriate, research-supported implementations, a prudent approach
would give credit only for audible unimodal alerts or for bi-modal
alerts that include audible alerts.'' Rivian stated ``[t]he agency
should award credit to systems that provide both audible and haptic
alerts and provide the option to turn either of them OFF based on
driver preference. These audible or haptic alerts should be in sync
with providing a visual alert of an impending collision. The agency
should recommend the decibel level and the haptic feedback location and
type as a baseline and based on research on reducing nuisance to the
driver.''
Given the lack of consensus within available research as to the
best location for a FCW haptic signal (seat belt, seat pan, steering
wheel, or brake pulse), and NHTSA's ongoing review of comments
submitted in response to the March 2022 request for comments, NHTSA is
not at this time proposing to require a haptic FCW component, but
invites comment on whether requiring FCW to contain a haptic component
presented via any location may increase FCW effectiveness or whether a
FCW haptic signal presented in only one specific, standardized location
should be allowed.
While the FCW auditory signal is envisioned as being the primary
means of warning the driver, providing a haptic FCW signal that would
complement or supplant the auditory warning signal would likely improve
FCW perception for hearing-impaired drivers. Some drivers also may
prefer an alternative modality to auditory warnings (e.g., due to
annoyance caused by the auditory warning). However, the degree of
additional benefit that may be accrued by requiring a haptic FCW signal
in addition to a well-designed auditory and visual FCW that meets the
specifications proposed is not known.
A haptic FCW signal, to be effective, would necessarily require the
driver to be in physical contact with the vehicle component through
which the haptic signal is presented in order to perceive the warning.
For example, if the driver is not wearing a seat belt, a haptic FCW
signal presented via the seat belt would not be effectively received. A
seat pan based haptic FCW signal would be unlikely to have such a non-
contact issue. NHTSA is interested in research data documenting the
comparison of a compliant auditory-visual FCW to that same FCW with an
added haptic component. NHTSA also welcomes any objective data
documenting the relative effectiveness of different haptic signal
presentation locations for FCW use.
3. Performance Test Requirements
This NPRM would require that, when approaching a lead vehicle
during testing, the subject vehicle must provide a forward collision
warning and subsequently apply the brakes to avoid a collision. This
performance requirement is conducted under a defined set of conditions,
parameters (e.g., relative vehicle speeds and distances), and test
procedures.
For all vehicle tests where the subject vehicle approaches a lead
vehicle, NHTSA is proposing that the minimum performance requirement is
complete avoidance of the lead vehicle. NHTSA chose the performance
criterion of collision avoidance because it maximizes the safety
benefits of the rule as compared to a metric that might permit a
reduced speed collision. NHTSA has tentatively concluded that a no-
contact criterion for the performance test requirements is practicable
to achieve, consistent with the need for safety, and may be necessary
to ensure test repeatability.
NHTSA also seeks comment on the potential consequences if vehicle
contact were allowed during testing. First, NHTSA seeks comment on how
allowing contact during testing would affect the safety benefits of AEB
systems. Second, NHTSA seeks comment on whether allowing contact during
testing would create additional testing burdens. Specifically, NHTSA is
concerned that any performance test requirement that allows for vehicle
contact not resulting in immediate test failure could result in the
non-repeatability of testing without expensive or time-consuming
interruptions to testing, and seeks comment on this concern. For
instance, if a test vehicle were to strike the lead vehicle test
device, even at a low speed, sensors on the vehicle could become
misaligned or the vehicle test device may be damaged, including in ways
that are not immediately observable. For example, damage to the test
device might affect the radar cross section that requires a long
verification procedure to discover.
4. Performance Test Scenarios
NHTSA is proposing three track test scenarios to evaluate AEB
performance. The test scenarios have the subject vehicle travelling
toward a lead vehicle which is ahead in the same lane. However, the
lead vehicle may be either stopped, moving at a constant but slower
speed, or decelerating to a stop.
These three tests were chosen because they represent the three most
common pre-crash scenarios involving a lead vehicle. A NHTSA research
study of heavy vehicles comprising the striking vehicle in rear-end
crashes in the United States determined that four pre-crash scenarios
exist in data of both fatal and non-fatal crashes.\143\ These four
scenarios include the three listed above, and also a ``cut-in'' case in
which a lead vehicle changed lanes or merged into the path of the heavy
vehicle just prior to the crash. The cut-in scenario was excluded from
the test scenarios for this proposal because the research study shows
that it was much less likely to occur than the other three
scenarios.\144\
---------------------------------------------------------------------------

\143\ Woodrooffe, J., et al. ``Performance Characterization and
Safety Effectiveness Estimates of Forward Collision Avoidance and
Mitigation Systems for Medium/Heavy Commercial Vehicles,'' Pg. 12.
Report No. UMTRI-2011-36, UMTRI (August 2012). Available at https://www.regulations.gov/document/NHTSA-2013-0067-0001 (last accessed
June 9, 2022).
\144\ The cut-in scenario represents less than 5% of the pre-
crash scenarios.
---------------------------------------------------------------------------

i. Stopped Lead Vehicle
This test recreates a roadway scenario where the subject vehicle
encounters a lead vehicle which is stopped ahead in the same lane.
Figure 5 shows the basic setup for the stopped lead vehicle scenario.
The subject vehicle is driven toward the stationary lead vehicle at a
constant speed, and the accelerator is only released if a forward
collision warning is issued. The test ends when the subject vehicle
either automatically stops without impact, or proceeds to strike the
lead vehicle.
NHTSA proposes testing under two conditions for the subject
vehicle: testing without any manual brake application (to test the CIB
component) and testing with manual brake application (to ensure that
the driver's application of the brake pedal does not inhibit the
functionality of the AEB system). Testing with no brake application
simulates a driver who does not intervene in response to an FCW alert
prior to a crash. Testing with brake application simulates a driver who
applies the brakes, but the manual brake application is insufficient to
prevent a collision.
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[[Page 43212]]

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ii. Slower-Moving Lead Vehicle
This test recreates a roadway scenario where the subject vehicle
encounters a lead vehicle that is moving at a constant but slower speed
ahead in the same lane. Figure 6 shows the basic setup for the slower-
moving lead vehicle scenario. The subject vehicle is driven toward the
lead vehicle at a constant speed, and its accelerator is then released
after the AEB system in the subject vehicle issues a forward collision
warning. The test ends when the subject vehicle either slows down to a
speed less than or equal to the lead vehicle's speed without impact or
strikes the lead vehicle. As with the stopped lead vehicle test, NHTSA
proposes testing under two conditions for the subject vehicle: without
any manual brake application and with manual brake application.
[GRAPHIC] [TIFF OMITTED] TP06JY23.006

iii. Decelerating Lead Vehicle
This test recreates a roadway scenario where the subject vehicles
encounter a lead vehicle that is slowing down ahead in the same lane.
At the start of the test, both the subject vehicle and lead vehicle
travel at the same constant speed, while maintaining a predetermined
relative distance, or headway. The lead vehicle then begins to
decelerate, reducing the headway. Once the AEB system in the subject
vehicle issues a forward collision warning, the subject vehicle's
accelerator is released. The test ends when the subject vehicle either
automatically stops without impact or strikes the lead vehicle. As with
the prior two tests, NHTSA proposes testing under two conditions for
the subject vehicle: without any manual brake application and with
manual brake application. Figure 7 shows the basic setup for the
decelerating lead vehicle scenario.
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[[Page 43213]]

5. Parameters for Vehicle Tests
The test procedures for each scenario reference a set of
parameters. These parameters are presented in Table 16, where each row
represents a potential combination of parameters to be used for a test
run. The parameters define the speeds, decelerations, headways, and
manual brake applications used for the choreography of the vehicle test
scenarios. Specifically, these include:

Subject Vehicle Speed (VSV)--speed at which the
subject vehicle travels toward the lead vehicle
Lead Vehicle Travel Speed (VLV)--speed at which the
lead vehicle travels in the same direction as the subject vehicle
Headway--the distance between the subject vehicle and the lead
vehicle
Lead Vehicle Deceleration--the rate at which the lead vehicle
reduces its speed
Manual Brake Application--specifies whether or not the service
brakes of the subject vehicle will be applied ``manually,'' or via a
brake controller

Table 16--Test Parameters When Approaching a Lead Vehicle
--------------------------------------------------------------------------------------------------------------------------------------------------------
Speed (km/h)
Test scenarios ------------------------------------------ Headway (m) Lead vehicle decel. (g) Manual brake
VSV VLV application
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stopped Lead Vehicle.............. Any 10-80............... 0 ........................ ....................... no.
Any 70-100.............. 0 ........................ ....................... yes.
Slower-Moving Lead Vehicle........ Any 40-80............... 20 ........................ ....................... no.
Any 70-100.............. 20 ........................ ....................... yes.
Decelerating Lead Vehicle......... 50...................... 50 Any 21-40............... Any 0.3-0.4............ no.
50...................... 50 Any 21-40............... Any 0.3-0.4............ yes.
80...................... 80 Any 28-40............... Any 0.3-0.4............ no.
80...................... 80 Any 28-40............... Any 0.3-0.4............ yes.
--------------------------------------------------------------------------------------------------------------------------------------------------------

Some of these parameters are proposed as ranges.\145\ The use of
ranges allows NHTSA to ensure AEB system performance remains consistent
under a variety of conditions and that no substantial degradation in
performance occurs at any point within the range. NHTSA tentatively
concludes that requiring a minimum performance only at discreet,
predetermined values within these proposed ranges may not ensure that
AEB system performance is sufficiently robust to meet the need for
safety.
---------------------------------------------------------------------------

\145\ In instances where an FMVSS includes a range of values for
testing and/or performance requirements, the use of the word ``any''
is consistent with 49 CFR 571.4.
---------------------------------------------------------------------------

i. Vehicle Speed Parameters
The proposed test speed ranges were selected considering two
primary factors. The first factor is the practical ability of AEB
technology to consistently operate and avoid contact with a lead
vehicle at the widest reasonable range of speeds. A larger range of
speeds could yield more safety benefits. Also, a larger range of speeds
will more thoroughly test the capabilities of the AEB system. NHTSA,
through its understanding of vehicle braking systems described in
established standards such as FMVSS Nos. 105 and 121, knows that
testing stopping distance at 60 mph is indicative of the service brake
performance over a range of speeds, and in those cases testing at a
single speed is acceptable. However, as observed in vehicle testing for
NHTSA research, AEB performance during testing at interstate speeds
does not necessarily indicate what the same system's performance will
be at lower speeds. Thus, NHTSA tentatively concludes that testing over
a range of speeds is necessary to fully assess AEB performance.
The second factor is the practical limit of safely conducting
vehicle tests of AEB systems. NHTSA's testing must be safe and
repeatable as permitted by track conditions and testing equipment. For
example, if the AEB system does not intervene as required or if test
parameters inadvertently fall outside of the specified limits, it
should be possible to safely abort the test. In the event the subject
vehicle does collide with the lead vehicle, the test should be designed
so that it does so in a manner that will not injure the testing
personnel nor cause excessive property damage. Additionally, test
tracks may be constrained by available space and there may be
insufficient space to accelerate a heavy vehicle up to a high speed and
still have sufficient space to perform a test. Many types of heavy
vehicles are not capable of accelerating as quickly as lighter vehicles
and reaching high test speeds may require long distances that exceed
what is available at many vehicle testing facilities. At approximately
100 km/h, the agency found that constraints with available test track
length, in conjunction with the time required to accelerate the vehicle
to the desired test speed, made performing these high speed tests with
heavy vehicles logistically challenging.\146\ The agency has
tentatively concluded that at this time the maximum practicable test
speed is 100 km/h.
---------------------------------------------------------------------------

\146\ During testing of a 2021 Freightliner Cascadia at speeds
approaching 100 km/h, NHTSA experienced difficulty establishing
valid test conditions due to insufficient track length.
---------------------------------------------------------------------------

The maximum speed of 100 km/h is included in the test speed range
when manual braking is present; the manual braking will guarantee a
speed reduction even if the AEB system does not activate before
reaching the lead vehicle, which would limit potential damage to the
test equipment and reduce other potential risks. When no manual braking
is allowed, the maximum test speed would be 80 km/h so that, in the
event the AEB system does not provide any braking at all, risk to
personnel and damage to test equipment are reduced. Over 82 percent of
rear-end crashes where the heavy vehicle is the striking vehicle occur
at speeds below 80 km/h.\147\ However, the majority of fatal crashes
occur at speeds above 80 km/h, and approximately 40 percent of these
occur at travel speeds between 80 and 100 km/h. The stopped lead
vehicle test scenario uses a no-manual-braking test speed range of 10
to 80 km/h and a manual-braking test speed range of 70 to 100 km/h.
Together, these test speed ranges overlap with the travel speeds at
which heavy vehicle rear-end crashes occur in the real world, while
reducing the potential risk and damage to test equipment and vehicles
and not

[[Page 43214]]

exceeding the practical physical size limits of test tracks.
---------------------------------------------------------------------------

\147\ This is based on analysis of 2017-2019 crash data.
---------------------------------------------------------------------------

Similarly, the slower-moving lead vehicle test scenario uses speed
ranges of 40 to 80 km/h and 70 to 100 km/h for the subject vehicle,
while the lead vehicle travels ahead at a constant speed of 20 km/h.
The lower end of the subject vehicle test speed range is 40 km/h so
that the subject vehicle is traveling faster than the lead vehicle. The
decelerating lead vehicle tests are run at either 50 or 80 km/h. This
test is performed at two discreet speeds rather than at ranges of
speeds because the main factors that test AEB performance are the
variation of headway, or the distance between the subject vehicle and
lead vehicle, and how hard the lead vehicle brakes. Additionally,
because these tests contain a larger number of variables requiring more
complex test choreography, limiting the test to two discreet test
speeds reduces the number of potential test conditions and reduces
potential test burden.
During each test run in any of the test scenarios, the vehicle test
speed will be held constant until the test procedure specifies a
change. NHTSA is proposing that vehicle speed would be maintained
within a tolerance range of 1.6 km/h of the chosen test value. This is
important for test consistency. Vehicle speed determines the time to
collision, which is a critical variable in AEB tests. In NHTSA's
experience, both the subject vehicle and lead vehicle speeds can be
reliably controlled within the 1.6 km/h tolerance range, and speed
variation within that range yields consistent test results. A tighter
speed tolerance is burdensome and unnecessary for repeatability as it
may result in a higher test-rejection rate, without any greater
assurance of accuracy of the test track performance.
NHTSA's vehicle testing suggested that the selected speed ranges
for the various scenarios are within the capabilities of at least some
recent model year AEB-equipped production vehicles. For example, the
2021 Freightliner Cascadia avoided collision in the stopped lead
vehicle test at all speeds between 40 and 85 km/h, most speeds between
30 and 90 km/h (except 30 and 60 km/h) in the slower-moving lead
vehicle test, and in all decelerating lead vehicle tests that were run
at the proposed parameters. This vehicle's AEB system did not prevent a
collision at lower speeds between 20 and 35 km/h for the stopped lead
vehicle test. However, the 2021 Dodge Ram 550 avoided collision in all
stopped lead vehicle tests from 10 to 40 km/h. In many test cases where
current AEB systems did not prevent a collision, the AEB significantly
reduced the speed before the collision. While these current AEB systems
perform a bit differently depending on the vehicle, given that this
notice proposes a lead time for manufacturers to come into compliance
with the proposed performance requirement, the agency expects that
compliance with these requirements would be achievable.
ii. Headway
The decelerating lead vehicle test scenario includes a parameter
defining how far ahead the lead vehicle is from the subject vehicle at
the beginning of the test, which is referred to as headway. Headway and
lead vehicle deceleration are the main factors for the dynamics of the
decelerating lead vehicle test since both the lead and subject vehicles
start the test at the same constant speed. At the start of the test,
when the vehicles are both travelling at 50 km/h, the proposed headway
specification is any distance between 21 m and 40 m.\148\ When the
vehicles are both travelling at 80 km/h, the proposed headway
specification is any distance between 28 m and 40 m. Headways are
proposed as a range in order to assure AEB functionality over a wider
range of driving scenarios. A basic kinematic simulation of heavy
vehicle AEB braking under the proposed test parameters, assuming
factors such as AEB response time and foundation brake reaction time/
deceleration similar to what was observed in testing, indicated that
headways shorter than 21 and 28 m would not be realistic to achieve and
would inevitably result in a collision.
---------------------------------------------------------------------------

\148\ The bounds of the headway range are consistent with the
headways in the April 2021 European New Car Assessment Programme
(Euro NCAP), Test Protocol--AEB Car-to-Car systems, Version 3.0.3
for the same scenario.
---------------------------------------------------------------------------

The upper limit of 40 m was chosen because testing at longer
headways does not provide additional insight into AEB performance with
regard to decelerating lead vehicles. At headways greater than 40 m,
the lead vehicle decelerating may come to a full stop prior to the
subject vehicle actuating the brakes. This essentially becomes a
stopped lead vehicle test. Allowing for a range of headways during
testing also makes the choreography of the test possible by providing a
tolerance for the headway. At the start of the test, the speed of both
the subject vehicle and lead vehicle are the same and are maintained
within the tolerance specified (plus or minus 1.6 km/h). As each
vehicle's speed fluctuates a bit differently within these bounds, in
turn the headway between the vehicles accordingly fluctuates as well.
As long as the headway fluctuation is within the proposed range, the
test can still be considered valid, and no headway tolerance needs to
be established.
iii. Lead Vehicle Deceleration Parameter
The decelerating lead vehicle test scenario includes a deceleration
parameter that dictates how quickly the lead vehicle will slow down in
front of the subject vehicle. The agency has tentatively concluded that
this parameter range of 0.3g to 0.4g represents real-world, manual
application of the service brake. Previous NHTSA research had
identified 3.0 m/s\2\ (.306g) as ``reasonably comfortable for passenger
car occupants'' and that on average, drivers brake in such a manner
that the vehicle decelerates at an average of 0.48g when presented with
a unexpected obstacle.\149\ The upper limit of the lead vehicle braking
is proposed at 0.4g to avoid a test condition in which the lead vehicle
would provide greater brake inputs than those necessary to meet the
minimum stopping distance requirements. NHTSA took into consideration
the stopping distance requirements for heavy vehicles under FMVSS Nos.
105 and 121 and the resulting average decelerations that those vehicles
would be required to achieve. For example, an air-braked tractor
trailer under FMVSS No. 121 would need to brake at 0.41g to meet the
stopping distance of 310 ft from 60 mph.\150\ Given the headway
parameters and vehicle speeds in this proposal, the agency believes a
lead vehicle deceleration above 0.4g would create a requirement that
could effectively reduce the minimum stopping distance requirements for
vehicles generally.
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\149\ Gregory M. Fitch, Myra Blanco, Justin F. Morgan, Jeanne C.
Rice, Amy Wharton, Walter W. Wierwille, and Richard J. Hanowski
(April 2010). Human Performance Evaluation of Light Vehicle Brake
Assist Systems: Final Report (Report No. DOT HS 811 251) Washington,
DC: National Highway Traffic Safety Administration, pgs. 13 and 101.
\150\ This assumes an average deceleration that is achieved
after an initial brake actuation time of 0.45 seconds, as this is
the maximum actuation time allowed by FMVSS No. 121.
---------------------------------------------------------------------------

6. Manual Brake Application in the Subject Vehicle
Each of the three lead vehicle test scenarios includes tests that
are conducted with manual brake application in the subject vehicle. The
process for testing with manual brake application is identical to what
is considered a test for dynamic brake support or DBS in NHTSA's NCAP
for light vehicles. While the term DBS is

[[Page 43215]]

not usually associated with heavy vehicles, NHTSA is including this
requirement in this proposal to ensure that the driver's application of
the brake pedal does not inhibit the functionality of the AEB system if
the driver's brake application is insufficient to avoid a crash. The
manual brake application procedure specifies that the subject vehicle's
service brakes are applied by using a robotic brake controller to
ensure accurate and consistent test conduct.
A NHTSA study that examined light vehicle drivers' behavior in
response to potential frontal crash situations found that they
typically exhibit multi-stage braking behavior.\151\ This means that
the drivers initially applied and held the brake moderately, and then
continued to a full application if perceived to be necessary. A
subsequent NHTSA study concluded that a significant portion of heavy
vehicle operators display the same multi-stage braking behavior.\152\
The agency believes that in real world cases where the operator may
apply insufficient brake force to avoid a rear-end collision, an AEB
system should apply the necessary supplemental braking necessary to
avoid a collision. Furthermore, by using manual brake application in
the test scenarios, NHTSA is able to test AEB performance at higher
test speeds.
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\151\ Mazzae, E., Barickman, F., Scott Baldwin, G., and
Forkenbrock G., ``Driver Crash Avoidance Behavior with ABS in an
Intersection Incursion Scenario on Dry Versus Wet Pavement,'' SAE
Technical Paper 1999-01-1288, 1999, doi:10.4271/1999-01-1288.
\152\ Every, J., Salaani, M., Barickman, F., Elsasser, D., et
al., ``Braking Behavior of Truck Drivers in Crash Imminent
Scenarios,'' SAE International Journal of Commercial Vehicles,
7(2):2014, doi:10.4271/2014-01-2380.
---------------------------------------------------------------------------

In real world cases, the brake pedal can be applied by a heavy
vehicle operator in an infinite number of ways (varying force, reaction
time, duration, etc.). Since the manual brake application represents an
operator's response to an unexpected obstacle and the forward collision
warning, the agency is proposing a brake pedal application that results
in a mean deceleration of 0.3g. A heavy vehicle field study by NHTSA
indicated that when presented with an FCW triggered by a valid object
and requiring a crash avoidance maneuver, the operators braked on
average at a maximum of 0.3g.\153\ Manually applying the brake at 0.3g
also is a low enough value to improve the capability of observing an
AEB automatic braking intervention that is occurring simultaneously on
top of that. The minimum stopping distance requirements for heavy
vehicles in existing FMVSSs require braking at around 0.4g. Thus
hypothetically, if a heavy vehicle's service brakes were manually
applied at a higher deceleration of 0.4g for example, and the brakes
were only capable of a maximum of 0.4g of deceleration, AEB
intervention would be incapable of producing additional deceleration
and would not be observable.
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\153\ Grove, K., Atwood, J., Hill, P., Fitch, G., Blanco, M.,
Guo, F., . . . & Richards, T. (2016, June). Field study of heavy-
vehicle crash avoidance systems. (Final report. Report No. DOT HS
812 280). Washington, DC: National Highway Traffic Safety
Administration.
---------------------------------------------------------------------------

There are two methods to perform the manual brake application--
using either displacement feedback or hybrid feedback. Both methods are
intended to be carried out by a robotic brake pedal controller in
closed loop operation, and the method that is most suitable to the
subject vehicle is chosen. Regardless of the method, it is necessary
initially to determine a pedal position which, in the absence of any
automatic braking from the AEB system, results in an average vehicle
deceleration of 0.3g. The displacement feedback method then simply
requires moving the brake pedal to the 0.3g position quickly, at a rate
of 254 mm/s,\154\ and then maintaining that position. However,
automatic braking in certain vehicles requires the pedal position to
move further toward the floor, and can cause conflict with the
displacement feedback method's control of pedal position, in turn
adversely affecting test results.\155\ The hybrid feedback pedal
control method provides a solution to this conflict. The hybrid method
initially requires the same pedal position control, but then almost
immediately begins to control the force on the pedal (and not the
position) to maintain the 0.3g deceleration. If the AEB system
thereafter requires further movement of the pedal, the brake controller
is able to ``follow'' the pedal while still applying the appropriate
force.\156\ NHTSA is proposing that the brake will be applied 1.0
second after the vehicle has provided a FCW; this is based on the
average time it takes a driver to react when presented with an
obstacle.\157\ Although these average decelerations and reaction times
are based on behavior of light vehicle drivers, we feel that it is
sufficient basis to simulate a scenario in which a heavy vehicle
operator brakes partially and insufficiently to fully avoid a rear-end
collision.
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\154\ Previous NHTSA research related to AEB examined pedal
application rates by drivers in emergency and non-emergency
situations, and determined that pedal application rate is important
in AEB testing with manual braking, and that the appropriate
application rate is 254 mm/s. NHTSA, August 2014. Automatic
Emergency Braking System (AEB) Research Report, An Update of the
June 2012 Research Report Titled, ``Forward-Looking Advanced Braking
Technologies Research Report.'' Docket NHTSA-2012-0057-0037.
\155\ NHTSA, August 2014. Automatic Emergency Braking System
(AEB) Research Report, An Update of the June 2012 Research Report
Titled, ``Forward-Looking Advanced Braking Technologies Research
Report.'' Docket No. NHTSA-2012-0057-0037.
\156\ Id.
\157\ Previous NHTSA research has shown that on average, it
takes drivers 1.04 s to begin pressing the brake when presented with
an unexpected obstacle and 0.8 s when presented with an anticipated
obstacle. Gregory M. Fitch, Myra Blanco, Justin F. Morgan, Jeanne C.
Rice, Amy Wharton, Walter W. Wierwille, and Richard J. Hanowski
(2010, April) ``Human Performance Evaluation of Light Vehicle Brake
Assist Systems: Final Report'' (Report No. DOT HS 811 251),
Washington, DC: National Highway Traffic Safety Administration, p.
101.
---------------------------------------------------------------------------

B. Conditions for Vehicle Tests

The test conditions are used to control the environmental, road
surface, subject vehicle, and equipment conditions to ensure
consistency both to define potential variabilities in conditions under
which an AEB system would be expected to operate while also providing
consistent conditions to reduce test variability due to extraneous
factors. NHTSA recognizes that there are an unlimited number of non-
ideal environmental conditions present in the real world, and it would
be unreasonable to attempt to reproduce most of them within practical
constraints in the testing environment. Thus, in many cases, the
proposed test conditions were chosen to represent near-ideal conditions
with the goal of reducing variability in the test results. For example,
if testing were conducted at below-freezing temperatures with snowfall,
it would be difficult to interpret whether poor test results were due
to the AEB system or reduced road surface friction.
Many of the proposed conditions were selected based on research
data and engineering practices, and reasonable deduction. In some
cases, as appropriate, the agency considered that conditions should be
the same or similar to what is specified in other heavy vehicle brake-
related FMVSS. This usage of pre-established conditions may help reduce
testing burden, since fewer testing conditions would need to be
adjusted between different FMVSS brake-related compliance tests. It
also ensures that the minimum stopping distance requirements in the
braking standards would be achievable during an AEB test.
Each test procedure for the three scenarios specifies a point at
which thereafter the test conditions described in this section apply
and will be maintained. For the stopped lead vehicle and slower-moving
lead vehicle

[[Page 43216]]

test scenarios, this point is at a 5 second time to collision. For the
decelerating lead vehicle test scenario, this point is 1 second prior
to the onset of lead vehicle deceleration.
1. Environmental Conditions
The ambient temperature range specified in this proposal is 2 to 40
degrees Celsius; this is the same range as specified in FMVSS No. 136,
which avoided testing at 0 degrees Celsius because it could impact tire
performance and in turn the variability of test results.
The maximum wind speed is 5 m/s, which is the same as what is
specified in FMVSS No. 136. This value was chosen to reduce the
potential lateral displacement of certain heavy vehicles.
NHTSA considered that certain environmental conditions should be
near-ideal to prevent sensor performance degradation and maintain
repeatability of vehicle testing. First, ambient illumination would be
at or above 2,000 lux. This represents daytime illumination that is at
a minimum equivalent to an overcast day.\158\ A NHTSA study has shown
that darkness can cause degradation of sensor performance.\159\ NHTSA
analysis shows that 87 percent of heavy vehicle rear-end crashes occur
during daylight conditions.\160\ Therefore, NHTSA tentatively concludes
that daylight testing is necessary to ensure that AEB systems address
the rear-end crash safety problem.
---------------------------------------------------------------------------

\158\ During an overcast day (no sun), when the solar altitude
is around 6 degrees, the light intensity on a horizontal surface is
around 2,000 lux. Illuminating Engineering Society of North America.
1979. ``Recommended Practice of Daylighting.''
\159\ NHTSA, August 2014. ``Automatic Emergency Braking System
(AEB) Research Report--An Update of the June 2012 Research Report
Titled, `Forward-Looking Advanced Braking Technologies Research
Report.' '' Docket NHTSA-2012-0057-0037.
\160\ Data are from 2017-2019 FARS and CRSS crash databases, as
discussed in the PRIA section on initial AEB target population.
---------------------------------------------------------------------------

Second, during testing, the sun would not be below 15 degrees of
elevation and within 25 degrees laterally from the center plane of the
subject vehicle. This specification reduces the likelihood of glare or
washout for camera-based sensors that could lead to degradation of
sensor and AEB system performance.\161\
---------------------------------------------------------------------------

\161\ NHTSA, August 2014. ``Automatic Emergency Braking System
(AEB) Research Report--An Update of the June 2012 Research Report
Titled, `Forward-Looking Advanced Braking Technologies Research
Report.' '' Docket NHTSA-2012-0057-0037.
---------------------------------------------------------------------------

Visibility also would not be affected by fog, smoke, ash or other
particulate, as recommended in previous agency research findings.\162\
This improves test repeatability and also aligns with many real-world,
rear-end crash conditions. A review of NHTSA's crash data indicates
that 81 percent of those occur when the weather conditions are clear or
cloudy and with no precipitation.\163\
---------------------------------------------------------------------------

\162\ NHTSA, August 2014. ``Automatic Emergency Braking System
(AEB) Research Report--An Update of the June 2012 Research Report
Titled, `Forward-Looking Advanced Braking Technologies Research
Report.' '' Docket NHTSA-2012-0057-0037.
\163\ This is also supported by another study (Grove, Atwood,
Fitch and Blanco, M, 2016, ``Field Study of Heavy-Vehicle Crash
Avoidance Systems'') which concluded that over 88 percent of heavy
vehicle crashes occurred when the conditions were, clear, partly
cloudy, or overcast.
---------------------------------------------------------------------------

2. Road Surface Conditions
The road surface upon which vehicle tests will be conducted must
also be in a defined condition to help achieve repeatable testing. The
proposed conditions specify that the road surface is free of debris,
irregularities, or undulations, such as loose pavement, large cracks,
or dips. These could affect the vehicle's ability to brake properly or
maintain its heading, and ultimately reduce the repeatability of a
test. The test surface is also required to be level, with a slope
between 0 and 1 degrees, because the slope of a road surface can affect
the performance of an AEB-equipped vehicle.\164\ A surface that slopes
up and down could obstruct a sensor's view of an object ahead. It could
also influence the dynamics and layout involved in the proposed AEB
test scenarios, as travelling up or down a slope makes braking to a
stop more or less difficult. In order to have predictable tire
adherence under braking, the surface must also be dry and have a
controlled coefficient of friction. NHTSA is proposing that the test
track surface have a peak friction coefficient of 1.02 when measured in
accordance with ASTM International (ASTM) E1337 \165\ using an ASTM
F2493 standard reference test tire and without water delivery.\166\
Surface friction is a critical factor in brake system performance
testing, including AEB, since it correlates with tire grip and the
achievable stopping distance. The presence of moisture will
significantly change the measured performance of a braking system. A
dry surface is more consistent and provides for greater test
repeatability. Also, the proposed peak friction coefficient is the same
value that NHTSA uses for brake performance testing.
---------------------------------------------------------------------------

\164\ Kim, H. et al., ``Autonomous Emergency Braking Considering
Road Slope and Friction Coefficient,'' International Journal of
Automotive Technology, 19, 1013-1022 (2018).
\165\ ASTM International, ASTM E1337, ``Standard Test Method for
Determining Longitudinal Peak Braking Coefficient (PBC) of Paved
Surfaces Using Standard Reference Test Tire.''
\166\ See 87 FR 34800 (June 8, 2022), Final Rule, Federal Motor
Vehicle Safety Standards, Consumer Information; Standard Reference
Test Tire.
---------------------------------------------------------------------------

This proposal specifies up to two straight lines be marked on the
test surface to simulate lane markings. In order to provide flexibility
for different road configurations at a variety of test track
facilities, lane markings may or may not be present during testing. If
present, the lines would be of any color or configuration (e.g., solid,
dashed, double-line, etc.). If two lines are used, they would be
parallel to each other and between 2.7 to 4.5 m apart, which is
representative of typical lane widths.
Lastly, the environment would not contain obstructions that could
interfere with detection of a lead vehicle or other test equipment
ahead and have an unintentional effect on the field of view of the AEB
system, in turn compromising test repeatability. Thus, the subject
vehicle during testing would not travel beneath overhead structures
such as signs, bridges, or gantries, and each compliance test would be
conducted without any vehicles, obstructions, or stationary objects
within one lane width of either side of the subject vehicle path unless
called for in the test procedure.
3. Subject Vehicle Conditions
Many of the subject vehicle conditions exist to ensure that a
vehicle chosen for testing is in a working condition that represents
the vehicle as it is sold into the market, and capable of performing as
intended by the manufacturer. Thus, the vehicle conditions specify that
no AEB malfunction telltale is active, vehicle components ahead of AEB
sensors are clean and do not obstruct the sensors, the original tires
are installed and properly inflated, and non-consumable fluids (e.g.,
brake fluid, engine coolant, etc.) are full.
Other conditions exist to ensure that vehicle performance is
comparable to that found in the real world. Prior to testing, the
vehicle's service brakes are burnished according to the burnishing
procedures already used in FMVSS No. 121 or 105 testing, as appropriate
for the vehicle prior to the beginning of testing. Burnishing helps to
gradually seat and condition new brake components, particularly the
brake pads and rotors/drums, which come into contact and provide
friction under braking. Burnishing helps achieve optimal and repeatable
brake performance. If burnishing was done previously, for example due
to the running of compliance tests for other FMVSS, it would not be
repeated.
The agency also proposes that the brake temperatures be between 66
and

[[Page 43217]]

204 degrees Celsius prior to the beginning of a test, which is the same
as specified in FMVSS No. 136. In the agency's experience, this initial
temperature range allows the brakes to perform well without being under
or over heated during testing, and the upper end of 204 degree Celsius
does not require unreasonably long cool-down time between test runs.
The agency has also considered that vehicles may have adjustable
characteristics or configurable systems that a vehicle operator may
choose to adjust, and some of these are factors that could affect the
outcome of an AEB test. Since each vehicle operator could potentially
choose different settings for these systems, the testing would ensure
that AEB systems are capable of meeting the test requirements
regardless of which choices were made. Accordingly, this proposal
specifies that these adjustable factors will be nearly in any
configurable level during testing. Consumable fluids (e.g., fuel,
diesel exhaust fluid, etc.) and propulsion battery charge will be
between 5-100 percent of their capacity. Cruise control systems would
be tested in any available setting, including adaptive cruise control
modes. In the event that adaptive cruise control is engaged and remains
engaged during the event, the FCW would not be required. This is
because an adaptive cruise control system is intended to slow the
vehicle to avoid a collision prior to a collision being imminent and
without notification to the driver.\167\
---------------------------------------------------------------------------

\167\ Adaptive cruise control is a driver assistance technology
that automatically adjusts vehicle speed to maintain a certain
distance from a vehicle ahead.
---------------------------------------------------------------------------

Forward collision warnings would be tested in any configurable
setting. If the vehicle is equipped with an engine-braking system,
tests would be conducted with the system either engaged or disengaged.
The controls for the headlamps and regenerative braking would be tested
in any available position.
Regarding the weight of the subject vehicle during testing, this
proposal specifies that the vehicle is loaded to its gross vehicle
weight rating. Truck tractors will be loaded to its GVWR by connecting
a control trailer. The specifications for this control trailer, which
is an unbraked, single-axle flatbed, are equivalent to those found in
FMVSS No. 136. The agency believes it is important to test the
performance of AEB systems when the vehicle is at its heaviest
allowable condition, because heavy vehicles often travel in a fully
loaded condition and it generally presents the most challenging
scenario for braking (i.e., stopping a heavier vehicle is more
difficult). This loading condition is identical to the loaded condition
specified for FMVSS stopping distance assessment. This may improve
testing efficiency for NHTSA by having fewer loading conditions
specified among FMVSS.
Finally, because a vehicle will be tested at its GVWR, this
proposal specifies that, if a vehicle is equipped with a liftable axle,
it will be placed in the down position during testing.

C. Proposed Requirements for False Activation

1. No Automatic Braking Requirement
NHTSA proposes a requirement that the subject vehicle, when
presented with two false activation test scenarios, must not
automatically apply braking that results in a peak deceleration of more
than 0.25g when manual braking is not applied, nor a peak deceleration
of more than 0.45g when manual braking is applied. False activation
refers to cases where the AEB systems automatically activates the
service brakes although there is no object present in the path of the
vehicle with which it would collide. The associated vehicle tests are
run both with and without manual braking. During test runs without
manual braking, the AEB system must not initiate braking that results
in a peak deceleration of more than 0.25g. A 0.25g deceleration is
below the 0.3g threshold described earlier as a comfortable
deceleration which has a low probability of creating safety concerns
such as rear-end crashes (if the subject vehicle would brake too
hard).\168\ Also, 0.25g is an easily measurable deceleration when
testing.
---------------------------------------------------------------------------

\168\ Gregory M. Fitch, Myra Blanco, Justin F. Morgan, Jeanne C.
Rice, Amy Wharton, Walter W. Wierwille, and Richard J. Hanowski
(2010, April) Human Performance Evaluation of Light Vehicle Brake
Assist Systems: Final Report (Report No. DOT HS 811 251) Washington,
DC: National Highway Traffic Safety Administration, p. 13.
---------------------------------------------------------------------------

During test runs when manual braking is being applied, the AEB
system must not initiate braking that results in a peak deceleration of
more than 0.45g. When testing using manual braking, the goal is to have
a manual braking deceleration of 0.3g, and so the AEB system must not
cause more than approximately 0.15g of additional deceleration. This
0.15g amount is less than the 0.25g of peak deceleration permitted in
tests without manual braking--however, allowing the same 0.25g above
manual braking would mean that up to a total peak deceleration of 0.55g
would be permitted. Because 0.55g could exceed the maximum deceleration
capacity of certain heavy vehicles, it would, in turn, render the test
impossible to fail for those vehicles. Therefore, the lower threshold
of additional deceleration is proposed for false activation tests with
manual braking.
2. Vehicle Test Scenarios
Under this proposal, the false activation requirement would be
evaluated by executing two vehicle test scenarios--a steel trench plate
test and a pass-through test. The steel trench plate test was chosen
because in previous agency testing that included eight different false
activation test scenarios, the steel trench plate scenario was the only
one that produced false activation of the AEB system.\169\ The pass-
through test is similar to the United Nations Economic Commission for
Europe (UNECE) Regulation 131 pass-through test.\170\
---------------------------------------------------------------------------

\169\ Snyder, A., Martin, J., & Forkenbrock, G. (2013, July).
``Evaluation of CIB system susceptibility to non-threatening driving
scenarios on the test track.'' (Report No. DOT HS 811 795).
Washington, DC: National Highway Traffic Safety Administration.
\170\ UNECE Regulation 131, ``Uniform provisions concerning the
approval of motor vehicles with regard to the Advanced Emergency
Braking Systems (AEBS),'' see 6.8 False reaction test, U.N.
Regulation No. 131 (Feb. 27, 2020), available at https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2015/R131r1e.pdf.
---------------------------------------------------------------------------

The proposed false activation tests establish only a baseline for
system functionality. For practical reasons they are not comprehensive,
nor sufficient to eliminate susceptibility to false activations in the
myriad of circumstances in the real world. However, the proposed tests
are a practicable means to establish a minimum threshold of
performance. The agency expects that vehicle manufacturers will design
AEB systems to thoroughly address the potential for false
activations.\171\ Manufacturers have a strong market incentive to
mitigate false positives and have been successful even in the absence
of specific requirements.
---------------------------------------------------------------------------

\171\ From NHTSA's NCAP Request for Comments notice regarding
AEB: ``Specifically, the Alliance stated that vehicle manufacturers
will optimize their systems to minimize false positive activations
for consumer acceptance purposes, and thus such tests will not be
necessary. Similarly, Honda stated that vehicle manufacturers must
already account for false positives when considering marketability
and HMI.'' 87 FR 13452 at 13460.
---------------------------------------------------------------------------

i. Steel Trench Plate
This test recreates a roadway scenario where the subject vehicles
encounter a steel trench plate which is placed on the road surface
ahead in the same lane. The subject vehicle is driven at 80 km/h toward
the steel trench plate at a constant speed.

[[Page 43218]]

The tests would be conducted either with or without manual brake
application. Manual braking is included in these scenarios to ensure
that even when a vehicle's service brake is actuated, false activation
would not occur. For tests without manual braking, the accelerator is
only released if a forward collision warning is issued. For test with
manual braking, the accelerator is released at either the forward
collision warning or 1 second prior to the manual braking, whichever
occurs first. Manual braking begins when the subject vehicle is 1.1
seconds away from the steel trench plate. The test ends when the
subject vehicle either comes to a stop prior to crossing over the
leading edge of the steel trench plate, or it proceeds to drive over
the steel trench plate. Figure 8 shows the basic setup for the steel
trench plate scenario.
[GRAPHIC] [TIFF OMITTED] TP06JY23.008

Unlike the test scenarios in which the subject vehicle approaches a
lead vehicle, the agency proposes that the false activation tests be
run at a single speed rather than over a range of speeds. False
activations occurring at interstate speeds would create the most severe
unintended consequences of AEB braking. Therefore, the proposal
includes only a test at a single speed of 80 km/h.
ii. Pass-Through
This test recreates a roadway scenario where the subject vehicle
must travel between two parked cars that are adjacent to the left and
right sides of the subject vehicle's travel lane. The parked cars are
represented by two vehicle test devices. The lateral distance between
the parked cars is 4.5 m, which is sufficient to give the subject
vehicle enough space to pass between them and yet be close enough to be
in the field of view of AEB sensors. The subject vehicle is driven
along the center of the travel lane and toward the gap between the
parked cars at a speed of 80 km/h. For tests without manual braking,
the accelerator is only released if a forward collision warning is
issued. For tests with manual braking, the accelerator is released at
either the forward collision warning or 1 second prior to the manual
braking, whichever occurs first; manual braking begins when the front
plane of the subject vehicle is 1.1 seconds away from the rear plane of
the two parked cars).
[GRAPHIC] [TIFF OMITTED] TP06JY23.009

D. Conditions for False Activation Tests

The false activation requirement is conducted under a set test
conditions identical to those used for AEB tests. However, there are
equipment conditions which apply specifically to these false activation
tests.
The equipment conditions that apply to the two false positive
scenarios in this proposal relate to the steel trench plate and the
vehicles used for the pass-through test. The steel trench plate is a
piece of equipment that represents a steel plate typically used to
cover excavation holes or irregularities in the road surface during
construction work, and which is meant to be driven over by

[[Page 43219]]

vehicles. The steel trench plate specified in this proposal is made of
ASTM A36 steel, a common structural steel alloy, and has the dimensions
2.4 m x 3.7 m x 25 mm. Any metallic fasteners used to secure the steel
trench plate are flush with the top surface of the plate, to avoid
effectively increasing the profile height and radar cross-section of
the plate. The two vehicles used for the pass-through test are vehicle
test devices identical to those that would be used in the lead vehicle
testing.

E. Potential Alternatives to False Activation Tests

As alternatives to these two false activation tests, NHTSA is
considering requiring a robust documentation process, or specifying a
data storage requirement. NHTSA is considering requiring this
documentation and data in addition to or in place of the proposed false
activation tests. First, NHTSA seeks comment on the anticipated impacts
on safety and the certification burden if the agency were to finalize a
rule that did not contain one or both of the proposed false positive
tests.
The agency is considering requiring that manufacturers maintain
documentation demonstrating that process standards were followed
specific to the consideration of false application of automatic
braking. Other industries where safety-critical software-controlled
equipment failures may be life threatening (e.g., aviation,\172\
medical devices \173\) are regulated in some respects via process
controls ensuring that software development engineering best practices
are followed. This approach recognizes that system tests are limited in
their ability to evaluate complex, and constantly changing software
driven control systems.
---------------------------------------------------------------------------

\172\ 14 CFR 33.201(a) The engine must be designed using a
design quality process acceptable to the Federal Aviation
Administration, that ensures the design features of the engine
minimize the occurrence of failures, malfunctions, defects, and
maintenance errors that could result in an in-flight shutdown, loss
of thrust control, or other power loss.
\173\ 21 CFR 920.30(a)(1) Each manufacturer of any class III or
class II device, and the class I devices listed in paragraph (a)(2)
of this section, shall establish and maintain procedures to control
the design of the device in order to ensure that specified design
requirements are met.
---------------------------------------------------------------------------

Software development lifecycle practices that include risk
management, configuration management, and quality systems are used in
various safety-critical industries. ISO 26262 Road vehicles--Functional
safety and related standards are examples of methods for overseeing
software development practices. The agency is considering that a
process standards approach could be a viable and practical way of
regulating the risk of false positives, as false activation of braking
is a complex engineering problem with multiple factors and conditions
that must be considered in the real world. The agency seeks public
comment on all aspects of requiring that manufacturers document that
they have followed process standards in the consideration of the real-
world false activation performance of the AEB system.
Finally, the agency considered requiring targeted data recording
and storage of significant AEB activations. These data could then be
used by manufacturers to improve system performance, or by the agency
to review if a particular alleged false activation is part of a safety
defect investigation. The agency is considering requiring that an AEB
event that results in a speed reduction of greater than 20 km/h should
activate the recording and storage of the following key information:
date, time, engine hours (the time as measured in hours and minutes
during which an engine is operated), AEB activation speed, AEB exit
speed (vehicle speed at which the automatic braking is completely
released), AEB exit reason (e.g. driver override with throttle, or
brake, or system decision), location, and camera image data. This
information could be used by investigators to analyze the source of the
activation and determine if an activation was falsely applied. Such
data would need to be accessible by the agency and potentially the
vehicle operator for a full and transparent analysis. The agency seeks
comment on all aspects of this data collection approach as an
alternative to false positive testing, including whether this list of
potential elements is incomplete, overinclusive, or impractical.

F. Proposed Requirements for Malfunction Indication

NHTSA is proposing that AEB systems must continuously detect system
malfunctions. If an AEB system detects a malfunction that prevents it
from performing its required safety function, the vehicle would be
required to provide the vehicle operator with a warning. The warning
would be required to remain active as long as the malfunction exists
while the vehicle's starting system is on. NHTSA would consider a
malfunction to include any condition in which the AEB system fails to
meet the proposed performance requirements. NHTSA is proposing that the
driver must be warned in all instances of component or system failures,
sensor obstructions, environmental limitations (like heavy
precipitation), or other situations that would prevent a vehicle from
meeting the proposed AEB performance requirements. While NHTSA is not
proposing the specifics of the telltale, NHTSA anticipates that the
characteristics of the alert will be documented in the vehicle owner's
manual and provide sufficient information to the vehicle operator to
identify it as an AEB malfunction.
NHTSA considered proposing requirements pertaining to specific
failures and including an accompanying test procedure. For instance,
the agency could develop or use available tests that specify
disconnecting sensor wires, removing fuses, or covering sensors to
simulate field malfunctions. Such requirements are not included in the
proposed regulatory text, but NHTSA is interested in comments on this
issue.
NHTSA also considered proposing minimum requirements for the
malfunction telltale, to standardize ways of communicating to the
vehicle operator. NHTSA understands that some malfunctions of the AEB
system require repair (loose wires, broken sensors, etc.) while other
malfunctions are temporary and will correct themselves over time (ice
buildup on a camera). The agency considered requiring that the
malfunction telltale convey the actions that a driver should take when
a malfunction is detected. Such requirements are not included in the
proposed regulatory text, but NHTSA is interested in comments on this
issue. NHTSA seeks comment, including cost and benefit data, on the
potential advantages of specifying test procedures that would describe
how the agency would test a malfunction telltale and on the level of
detail that this regulation should require of a malfunction telltale.
Additionally, the agency considered requiring more details for the
telltale itself, such as a standardized appearance (color, size, shape,
illuminance). The agency seeks comment on the need and potential safety
benefits of requiring a standardized appearance of the malfunction
telltale and what standardized characteristics would achieve the best
safety outcomes.

G. Deactivation Switch

The proposed regulatory text does not permit vehicle manufacturers
to install a manual deactivation switch that would enable the vehicle
operator to switch off the AEB. The text is silent regarding the
permissibility of a switch but, under the framework of the FMVSS

[[Page 43220]]

and NHTSA's interpretations of the standards, a deactivation switch
would be prohibited if it would allow an AEB system to be deactivated
in any circumstance in which the standard requires an AEB system to
function. This is consistent with other FMVSS, such as FMVSS No. 108,
``Lamps, reflective devices, and associated equipment,'' which is
silent about a switch deactivating the stop lamps but where NHTSA has
interpreted the standard as prohibiting such a switch.\174\ Standards
in which a deactivation switch is permitted expressly permit the switch
in the regulatory text, for example, FMVSS No. 126, ``Electronic
stability control systems for light vehicles,'' where the standard
specifically permits and regulates the performance of a deactivation
switch,\175\ and FMVSS No. 208, ``Occupant crash protection,'' where
the standard permitted an on-off switch for the air bag for the front
passenger seat on particular vehicles.\176\
---------------------------------------------------------------------------

\174\ https://isearch.nhtsa.gov/files/23833.ztv.html (last
accessed August 31, 2022).
\175\ FMVSS No. 126, ``ESC systems for light vehicles,'' S5.4:
The manufacturer may include an ``ESC Off'' control whose only
purpose is to place the ESC system in a mode or modes in which it
will no longer satisfy the performance requirements of S5.2.1,
S5.2.2, and S5.2.3.
\176\ FMVSS No. 208, ``Occupant crash protection.'' FMVSS No.
208 was written such that it permited such switches only on vehicles
configured with no back seat or a back seat too small to accommodate
a rear-facing child restraint system. This was an interim step to
allow advanced air bag technology to mature and be fully
implemented.
---------------------------------------------------------------------------

NHTSA and FMCSA realize a switch or other method that could
deactivate a vehicle's AEB system could be useful in some
circumstances. There might be some heavy vehicle design or aftermarket
equipment installations where the configuration of the vehicle could
potentially interfere with the AEB sensing system. For example, a
snowplow might be attached in a manner that obstructs an AEB sensor.
Some vehicles may have uses where an AEB system may be incompatible
with its operating environment, for example, logging operations or
other on/off road environments.
Special conditions could be addressed by drafting the standard to
allow manual deactivation under limited circumstances when the system
is compromised. However, an FMVSS in which deactivation of the system
is easily accomplished would likely reduce the safety benefit of the
proposed rule. NHTSA seeks comments on the merits of and need for
manual deactivations of AEB systems. If the standard were to permit a
deactivation mechanism of some sort, how could NHTSA allow for
deactivations while ensuring the mechanism would not be abused or
misused by users? Alternatively, NHTSA is interested in comments on the
approach of the standard's restricting the automatic deactivation of
the AEB system generally but providing for special conditions in which
the vehicle is permitted to automatically deactivate or otherwise
restrict braking authority given to the AEB system.
NHTSA seeks comment on the merits of various performance
requirements related to manual deactivation switches for AEB systems.
The agency seeks comment on the appropriate performance requirements if
the agency were to permit the installation of a manually operated
deactivation switch. Such requirements might include limitations such
that the default position of the switch be ``AEB ON'' with each cycle
of the starting system or that the deactivation functionality be
limited to specific speeds.

H. System Documentation

NHTSA seeks comment on alternate regulatory approaches that might
be appropriate for regulating complex systems that depend heavily on
software performance. FMVSS have historically included requirements
that can be inspected or tested by the agency to verify compliance. In
some cases, such as in FMVSS No. 126, the agency has required
manufacturers to maintain technical documentation available for agency
review upon request to ensure that electronic stability control systems
were designed to mitigate vehicle understeer (49 CFR 571.126 S5.6). The
agency established this requirement in the absence of suitable test
procedures for evaluating understeer.
In the case of AEB, there are similar limits to testing systems in
controlled environments. AEB systems operating on roadways will be
subject to many scenes and stimuli that are not present on a test
track--e.g., precipitation, lighting, roadway curvature and elevation
changes, signage, other road users, animals, debris, etc.--and these
scenes and stimuli could potentially influence real world effectiveness
of AEB systems. The agency seeks comment on documentation requirements
that may be effective in encouraging real world effectiveness (e.g.,
maximizing true positive rate and minimizing false positive rate) and
in ensuring that AEB systems are developed and maintained in a manner
that minimizes performance risks.
The agency is considering requirements for manufacturers to
document a risk-based design approach identifying and mitigating
reasonably foreseeable risks alongside configuration management records
of all software/hardware updates performed by the manufacturer.
Manufacturers would also need to disclose certain servicing and system
limitation requirements and make AEB-related data stored in vehicles
available. Examples of requirements under consideration include:
Manufacturers must establish and maintain procedures that
provide a risk-based approach in designing, implementing, and (if
applicable) updating each system required under this standard.
Manufacturers must maintain documentation over the system lifetime
detailing the outcome of the risk-based approach taken to ensure the
safety of such systems.
Where servicing is required to maintain system
performance, each manufacturer must establish and maintain instructions
and procedures for performing and verifying that the servicing meets
the specified requirements.
Certain information must be disclosed to consumers at the
time of first sale in a single document such as an owner's manual:
[cir] If servicing requirements include periodic maintenance, the
maintenance schedule must be identified.
[cir] Manufacturers must include a statement describing the
limitations of AEB and explaining that AEB is an emergency system that
does not replace the need for normal actuation of the service brakes.
Each manufacturer must maintain documentation that
captures the full system configuration, including all hardware,
software, and firmware, for each vehicle at the time of first sale and
at the time of any update to the system configuration by the
manufacturer.
Each AEB system or a system that communicates with the AEB
system must store information logging at least the last three AEB
activation events or all AEB activation events occurring within the
past three drive cycles.
The vehicle must store the status of the AEB system
(active, inactive, disabled, warning, engaged, disengaged,
malfunctioning, etc.).
NHTSA believes that manufacturers that have installed AEB systems
in their fleet may already be meeting many of the documentation
requirements above. The agency seeks comment on the suitability of
these requirements and on any changes that manufacturers would have to
introduce in their internal processes and consumer-facing documentation
(e.g., owner's manuals). NHTSA is interested in learning

[[Page 43221]]

whether manufacturers find discrepancies between real-world performance
and data collected on test tracks with surrogate vehicles.

I. ESC Performance Test

This proposal would require nearly all heavy vehicles to have an
ESC system that meets the equipment requirements, general system
operational capability requirements, and malfunction detection
requirements of FMVSS No. 136. However, this proposal would not require
vehicles not currently required to have ESC systems to meet any test
track performance requirements for ESC systems because NHTSA is
conscious of the potential testing burden on small businesses and the
multi-stage vehicle manufacturers involved in class 3 through 6 vehicle
production. NHTSA requests comments on whether the agency should
establish performance requirements for ESC for all vehicles covered by
this proposal. If ESC performance requirements would be appropriate,
NHTSA seeks comment on which regulatory tests and requirements would be
appropriate for the class 3-8 vehicles which this notice proposes to
make applicable to FMVSS No. 136. NHTSA also seeks comment on whether
manufacturers of these vehicles should have the option to certify to
FMVSS No. 126 or FMVSS No. 136, whether a new ESC test procedure should
be developed for some or all of these vehicles, or whether NHTSA should
give the manufacturer the option to choose the ESC standard to which to
certify.
NHTSA conducted some limited ESC testing for class 3-6 vehicles, as
part of research efforts during the development of FMVSS No. 136, which
was established in 2015, and as part of its recent AEB testing.\177\
The ESC testing performed has however been sufficient to indicate that
the test procedures currently established in FMVSS Nos. 126 and 136
would require modification in order to better suit class 3 through 6
vehicles. For example, the vehicle test speeds specified in FMVSS No.
136, which are designed to induce ESC activation in class 7 and 8
trucks and buses at speeds under 48 km/h (30 mph), did not induce ESC
activation in the vehicles that were tested. This testing indicates
that the maximum test speeds and speed reduction requirements would
likely need to be modified.
---------------------------------------------------------------------------

\177\ This information is available in ``ESC Track Test Data for
Class 3-6 Vehicles,'' which has been placed in the docket identified
in the heading of this NPRM.
---------------------------------------------------------------------------

J. Severability

The issue of severability of FMVSSs is addressed in 49 CFR 571.9.
It provides that if any FMVSS or its application to any person or
circumstance is held invalid, the remainder of the part and the
application of that standard to other persons or circumstances is
unaffected. NHTSA seeks comment on the issue of severability.

VIII. Vehicle Test Device

NHTSA has proposed the same vehicle test device described below for
use in the proposed requirements for AEB for light vehicles. An
identical discussion of the vehicle test device appears in the NPRM
proposing the FMVSS for light vehicles.

A. Description and Development

To ensure repeatable and reproducible testing that reflects how a
subject vehicle would be expected to respond to an actual vehicle in
the real world, this proposal includes broad specifications for a
vehicle test device to be used as a lead vehicle or pass through
vehicle during testing. NHTSA is proposing that the vehicle test device
be based on certain specifications defined in ISO 19206-3:2021, ``Road
vehicles--Test devices for target vehicles, vulnerable road users and
other objects, for assessment of active safety functions--Part 3:
Requirements for passenger vehicle 3D targets.'' \178\ The vehicle test
device is a tool that NHTSA proposes to use to facilitate the agency's
compliance tests to measure the performance of AEB systems required by
the proposed FMVSS. This NPRM describes the vehicle test device that
NHTSA would use.
---------------------------------------------------------------------------

\178\ https://www.iso.org/standard/70133.html. May 2021.
---------------------------------------------------------------------------

The surrogate vehicle NHTSA currently uses in its research testing
is the Global Vehicle Target (GVT). The GVT is a full-sized, harmonized
surrogate vehicle developed to test crash avoidance systems while
addressing the limitations of earlier generation surrogate vehicles. To
obtain input from the public and from industry stakeholders, NHTSA
participated in a series of five public workshops and three radar
tuning meetings between August 2015 and December 2016. These workshops
and meetings provided representatives from the automotive industry with
an opportunity to inspect, measure, and assess the realism of prototype
surrogates during the various stages of development. Workshop and
meeting participants were permitted to take measurements and collect
data with their own test equipment, which they could then use to
provide specific recommendations about how the surrogate vehicle's
appearance, to any sensor, could be improved to increase realism.
After feedback from automotive vehicle manufacturers and suppliers
was incorporated into an earlier design of the GVT, a series of high-
resolution radar scans were performed by the Michigan Tech Research
Institute (MTRI) under NHTSA contract. These measurements provided an
independent assessment of how the radar characteristics of the GVT
compared to those from four real passenger cars.\179\ This study found
that the GVT has generally less radar scatter than the real vehicles to
which it was compared. However, MTRI found that ``even though the [GVT]
may more often reflect a greater amount of energy than the [real]
vehicles, it is not exceeding the maximum energy of the returns from
the vehicles. Thus, a sensor intended for the purpose of detecting
vehicles should perform well with the [GVT].'' \180\
---------------------------------------------------------------------------

\179\ The comparison passenger cars used were a 2008 Hyundai
Accent, a 2004 Toyota Camry, a 2016 Ford Fiesta hatchback, and a
2013 Subaru Impreza.
\180\ Buller, W., Hart, B., Aden, S., and Wilson, B. (2017, May)
``Comparison of RADAR Returns from Vehicles and Guided Soft Target
(GST),'' Michigan Technological University, Michigan Tech Research
Institute. Docket NHTSA-2015-0002-0007.
---------------------------------------------------------------------------

NHTSA also performed tests to determine the practicality of using
the GVT for test-track performance evaluations by examining how
difficult it was to reassemble the GVT after it was struck in a test.
Using a randomized matrix designed to minimize the effect of learning,
these tests were performed with teams of three or five members familiar
with the GVT reassembly process. NHTSA found that reassembly of the GVT
on the robotic platform takes approximately 10 minutes to complete;
however, additional time is often required to re-initialize the robotic
platform GPS afterwards.\181\
---------------------------------------------------------------------------

\181\ Snyder, Andrew C. et al., ``A Test Track Comparison of the
Global Vehicle Target (GVT) and NHTSA's Strikeable Surrogate Vehicle
(SSV),'' July 2019. https://rosap.ntl.bts.gov/view/dot/41936.
---------------------------------------------------------------------------

Finally, NHTSA conducted its own crash imminent braking tests to
compare the speed reduction achieved by three passenger cars as they
approached the GVT, compared to the Strikable Surrogate Vehicle (SSV),
the surrogate vehicle NHTSA currently uses for its NCAP AEB tests.
These tests found that any differences that might exist between the GVT
and the SSV were small enough to not appreciably influence the outcome
of vehicle testing.\182\
---------------------------------------------------------------------------

\182\ Id.
---------------------------------------------------------------------------

When used during AEB testing, the GVT is secured to the top of a
low-

[[Page 43222]]

profile robotic platform. The robotic platform is essentially flat and
is movable and programmable. The vehicle test device's movement can be
accurately and repeatably defined and choreographed with the subject
vehicle and testing lane through the use of data from the robotic
platform's on-board inertial measurement unit, GPS, and closed-loop
control facilitated by communication with the subject vehicle's
instrumentation. The shallow design of the robotic platform allows the
test vehicle to drive over it. The GVT is secured to the top of the
robotic platform using hook-and-loop fastener attachment points, which
allow the pieces of the GVT to easily and safely break away without
significant harm to the vehicle being tested if struck.
The internal frame of the GVT is constructed primarily of vinyl-
covered foam segments held together with hook-and-loop fasteners. The
GVT's exterior is comprised of multiple vinyl ``skin'' sections
designed to provide the dimensional, optical, and radar characteristics
of a real vehicle that can be recognized as such by camera and radar
sensors.\183\ If the subject vehicle impacts the GVT at low speed, the
GVT is typically pushed off and away from the robotic platform without
breaking apart. At higher impact speeds, the GVT breaks apart as the
subject vehicle essentially drives through it.
---------------------------------------------------------------------------

\183\ ``A Test Track Comparison of the Global Vehicle Target
(GVT) and NHTSA's Strikeable Surrogate Vehicle,'' DOT HS 812-698.
---------------------------------------------------------------------------

B. Specifications

The most recent, widely-accepted iteration of vehicle test device
specifications is contained in ISO 19206-3:2021.\184\ Using data
collected by measuring the fixed-angle/variable-range radar cross
section for several real vehicles, ISO developed generic
``acceptability corridors,'' which are essentially boundaries that the
vehicle test device's radar cross section must fit within to be deemed
representative of a real vehicle.\185\ All vehicles that ISO tested
have radar cross section measurements that fit within the boundaries
set forth in the ISO standard.
---------------------------------------------------------------------------

\184\ Road vehicles--Test devices for target vehicles,
vulnerable road users and other objects, for assessment of active
safety functions--Part 3: Requirements for passenger vehicle 3D
targets.
\185\ The vehicles tested to develop the ISO standard are: 2016
BMW M235i, 2006 Acura RL, 2019 Tesla Model 3, 2017 Nissan Versa,
2018 Toyota Corolla, 2019 Ford Fiesta.
---------------------------------------------------------------------------

This proposal would incorporate by reference ISO 19206-3:2021 into
NHTSA's regulations and specify that the vehicle test device meets
several specifications in ISO 19206-3:2021, in addition to other
specifications identified by NHTSA. Because the GVT was considered
during the development of ISO 19206-3:2021, the GVT would meet the
standard's specifications. However, should the design of the GVT change
or a new vehicle test device be developed, reference to the more
general specifications of ISO 19206-3:2021 should ensure that NHTSA is
able to test with such other vehicle test devices and should also
ensure that such vehicle test devices have properties needed by an AEB
system to identify it as a motor vehicle.
The vehicle test device's physical dimensions are proposed to be
consistent with those of the subcompact and compact car vehicle class.
The specific range of dimensions in this proposal for individual
surfaces of the vehicle test device are incorporated from ISO 19206-
3:2021, Annex A, Table A.4. These include specifications for the test
device's width and the placement of the license plate, lights, and
reflectors relative to the rear end of the vehicle test device.
The vehicle test device is proposed to have features printed on its
surface to represent features that are identifiable on the rear of a
typical passenger vehicle, such as tail lamps, reflex reflectors,
windows, and the rear license plate. The proposed color ranges for the
various surface features, including tires, windows, and reflex
reflectors are incorporated from ISO 19206-3:2021, Annex B, Tables B.2
and B.3. Table B.2 specifies the colors of the tires, windows, and
reflectors, which reflect the colors observed the in the real world.
The color of the exterior of the vehicle is specified to be a range
representing the color white, which provides a high color contrast to
the other identifiable features. White is also a common color for motor
vehicles.\186\ The proposed reflectivity ranges for the various
features on the vehicle test device are incorporated from ISO 19206-
3:2021, Annex B, Table B.1. Table B.3 specifies the recommended
minimum, mean, and maximum color range for the white body, specifically
the outer cover.
---------------------------------------------------------------------------

\186\ Globally, white was the most popular color for light
vehicles in 2021. https://gmauthority.com/blog/2022/02/white-was-
the-most-popular-car-color-again-in-2021/
#:~:text=According%20to%20PPG%2C%2035%20percent,by%20silver%20at%2011
%20percent.
---------------------------------------------------------------------------

Because many AEB systems rely on radar sensors in some capacity to
identify the presence of other vehicles, the vehicle test device must
have a radar cross section that would be recognized as a real vehicle
by an AEB system. In particular, the vehicle test device must have a
radar cross section consistent with a real vehicle when approached from
the rear over a range of distances.
NHTSA is proposing that the radar cross section of the vehicle test
device fall within an ``acceptability corridor'' when measured using an
automotive-grade radar sensor. This acceptability corridor would be
defined by the upper and lower boundaries specified by ISO 19206-
3:2021, Annex C, Equations C.1 and C.2, using the radar cross section
boundary parameters defined in ISO 19206-3:2021, Annex C, Table C.3 for
a fixed viewing angle of 180 degrees. NHTSA is aware that, unlike some
predecessor specification documents such as Euro NCAP Technical
Bulletin 025 from May 2018, ISO 19206-3:2021 does not specify that the
radar cross section measurements be verified using a specific model of
radar. Rather, the ISO standard specifies that the radar sensor used
have certain specifications and operational characteristics. NHTSA's
proposal similarly does not specify that the vehicle test device's
initial radar cross section be measured with a specific model or brand
of radar. NHTSA only proposes that the radar sensor used to validate
the radar cross section operate within the 76-81 GHz bandwidth, have a
horizontal field of view of at least 10 degrees, a vertical field of
view of at least 5 degrees, and a range greater than 100 m.
Additionally, NHTSA's proposal does not specify that the VTD's radar
cross section during in-the-field verifications be performed to
objectively assess whether the radar cross section still falls within
the acceptability corridor. NHTSA seeks comment about whether use of
the optional field verification procedure provided in ISO 19206-3:2021,
Annex E, section E.3 should be used.
Because the test procedures proposed in this rule only involve
rear-end approaches by the subject vehicle, NHTSA is at this time only
proposing to establish specifications applicable for the rear end of
the vehicle test device. NHTSA seeks comment on whether the
specifications for the vehicle test device should include all sides of
the vehicle. If NHTSA were to include, in a final rule, specifications
for all sides of a vehicle test device, NHTSA anticipates that those
specifications would also be incorporated from ISO 19206-3:2021.

C. Alternatives Considered

One alternative test device that NHTSA considered for use in this
proposal was the agency's self-developed Strikable Surrogate Vehicle
(SSV) device, which NHTSA currently uses in its NCAP testing of AEB
performance. NHTSA adopted the use of

[[Page 43223]]

the SSV as part of its 2015 NCAP upgrade, under which the agency began
testing AEB performance.\187\ The SSV resembles the rear section of a
2011 Ford Fiesta hatchback. The SSV is constructed primarily from a
rigid carbon fiber mesh, which allows it to maintain a consistent shape
over time (unless damaged during testing). To maximize visual realism,
the SSV shell is wrapped with a vinyl material that simulates paint on
the body panels and rear bumper, and a tinted glass rear window. The
SSV is also equipped with a simulated United States specification rear
license plate. The taillights, rear bumper reflectors, and third brake
light installed on the SSV are actual original equipment from a
production vehicle. NHTSA testing shows that AEB systems will recognize
the SSV and will respond in a way that is comparable to how they would
respond to an actual vehicle.\188\
---------------------------------------------------------------------------

\187\ 80 FR 68604.
\188\ 80 FR 68607.
---------------------------------------------------------------------------

While the SSV and GVT are both recognized as real vehicles by AEB
systems from the rear approach aspect, the SSV has several
disadvantages. The foremost disadvantage of the SSV is how easily it
can be irreparably damaged when struck by a subject vehicle during
testing, particularly at high relative velocities. While NHTSA has
tried to address this issue by attaching a foam bumper to the rear of
the SSV to reduce the peak forces resulting from an impact by the
subject vehicle, the SSV can still easily be damaged to a point where
it can no longer be used if the relative impact speed is sufficiently
high (greater than 40 km/h (25 mph)); this speed is much lower than the
maximum relative impact speed of 80 km/h (50 mph) potentially
encountered during the AEB tests performed at the maximum relative
speeds proposed in this notice). Also, unlike the GVT, which has its
movement controlled by precise programming and closed loop control, the
SSV moves along a monorail secured to the test surface, which may be
visible to a camera-based AEB system.
In addition to the vehicle test device specifications, NHTSA seeks
comment on specifying a set of real vehicles to be used as vehicle test
devices in AEB testing. UN ECE Regulation No. 152 specifies that the
lead vehicle be either a regular high-volume passenger sedan or a
``soft target'' meeting the specifications of ISO 19206-1:2018.\189\ UN
ECE regulation does not require the use of real vehicles as targets,
but rather offers them as an alternative to manufacturers to homologate
their systems, at their choice. Although NHTSA has tentatively
concluded that the specification in UN ECE Regulation No. 152 of any
high-volume passenger sedan is not sufficiently specific for an FMVSS,
NHTSA seeks comment on whether it should create a list of vehicles from
which NHTSA could choose a lead vehicle for testing. Unlike the UN ECE
regulation, which provides flexibility to manufacturers, inclusion of a
list of vehicles would provide flexibility to the agency in the
assessment of the performance of AEB systems. Such a list would be in
addition to the vehicle test device proposed in this document, to
provide assurance of vehicle performance with a wider array of lead
vehicles. For example, the list could include the highest selling
vehicle models in 2020.
---------------------------------------------------------------------------

\189\ U.N. Regulation No. 152, E/ECE/TRANS/505/Rev.3/Add.151/
Amend.1 (Nov. 4, 2020), available at https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2020/R152am1e.pdf.
---------------------------------------------------------------------------

Using actual vehicles has various challenges, including the
potential for risk to individuals conducting the tests and damage to
the vehicles involved, and assuring a safe testing environment that
could encounter high energy collisions between real vehicles in cases
of poor AEB system performance or AEB or test equipment malfunctions.
NHTSA seeks comment on the utility and feasibility of test laboratories
safely conducting AEB tests with real vehicles, such as through
removing humans from test vehicles and automating scenario execution,
and how laboratories would adjust testing costs to factor in the risk
of damaged vehicles.
Beyond the practical safety limits and cost of testing described
above, managing a list of relevant lead vehicles would require the
standard to be updated periodically to keep pace with the vehicle fleet
and to ensure that lead vehicles are available years after a final
rule. NHTSA seeks comments on the merits and potential need for testing
using real vehicles, in addition to using a vehicle test device, as
well as challenges, limitations, and incremental costs of such.

IX. Proposed Compliance Date Schedule

NHTSA proposes a two-tiered phase-in schedule for meeting the new
standard. For heavy vehicles currently subject to FMVSS No. 136, any
vehicle manufactured on or after the first September 1 that is three
years after the date of publication of the final rule must meet the
proposed heavy vehicle AEB standard. To illustrate, if the final rule
were published on October 1, 2023, the compliance date would be
September 1, 2027. For heavy vehicles not currently subject to FMVSS
No. 136, with some exclusions, those manufactured on or after the first
September 1 that is four years after the date of publication of the
final rule must meet the amendments to FMVSS No. 136 that would require
ESC systems and the proposed AEB requirements. In the provided example
of a final rule published on October 1, 2023, that date would be
September 1, 2028. Small-volume manufacturers, final-stage
manufacturers, and alterers would be provided an additional year, added
to the dates above, to meet the requirements of this proposal.
Consistent with 49 U.S.C. 30111(d), NHTSA has tentatively concluded
that good cause exists for this proposal to take effect more than one
year after publication of a final rule because it would not be feasible
for all heavy vehicles to be equipped with AEB systems that meet the
proposed performance requirements within one year. Furthermore, NHTSA
seeks comments on whether this proposed phase-in schedule appropriately
addresses challenges to the implementation of AEB for specific
categories of heavy vehicles. The agency is particularly interested in
information about single-unit trucks with permanently installed work-
performing equipment installed on the front of or extending past the
front of the vehicle (e.g., auger trucks, bucket trucks, cable reel
trucks, certain car carriers, etc.), where AEB sensors may be located.
NHTSA seeks comments to discern the best way to implement the
applicability of AEB on class 3-6 single-unit trucks, considering all
scenarios such as vehicle configuration, vehicle service applicability,
and cargo type, which, among other factors, can affect vehicle dynamics
and drivability. The manufacture of single-unit trucks is more complex
than that of truck tractors due to wider variations in vehicle weight,
wheelbase, number of axles, center of gravity height, and cargo type.
These factors, and others, bear on the calibration and performance of
ESC. For example, ESC system design depends on vehicle dynamics
characteristics, such as the total vehicle weight and location of that
weight (center of gravity), which will differ depending on the final
vehicle configuration. Because ESC has been a prerequisite for
voluntary adoption of AEB, single-unit trucks not having had ESC
requirements suggests that AEB implementation has been slower and that
there is a need for effective date flexibility.
NHTSA is also aware that many, if not most, manufacturers of
single-unit trucks are final-stage manufacturers, which are typically
small businesses. To

[[Page 43224]]

provide more flexibility to small businesses to meet the proposed rule,
this NPRM proposes to permit small-volume manufacturers, final-stage
manufacturers, and alterers an additional year to meet the requirements
of the final rule. The additional time would provide flexibility to the
manufacturers to install ESC and collaborate with AEB suppliers to meet
the proposed requirements.
FMCSA proposes that vehicles currently subject to FMVSS No. 136
(i.e., those manufactured on or after August 1, 2019, the initial
compliance date for FMVSS No. 136) would be required to comply with
FMCSA's proposed ESC regulation on the final rule's effective date.
Vehicles with a GVWR greater than 4,536 kilograms (10,000 pounds) not
currently subject to FMVSS No. 136 would be required to meet the
proposed ESC regulation on or after the first September 1 that is five
years after the date of publication of the final rule.
FMCSA proposes that, for vehicles currently subject to FMVSS No.
136, any vehicle manufactured on or after the first September 1 that is
three years after the date of publication of the final rule would be
required to meet the proposed heavy vehicle AEB standard. FMCSA
proposes that vehicles with a gross vehicle weight rating greater than
4,536 kilograms (10,000 pounds) not currently subject to FMVSS No. 136
and vehicles supplied to motor carriers by small-volume manufacturers,
final-stage manufacturers, and alterers would be required to meet the
proposed heavy vehicle AEB standard on or after the first September 1
that is five years after the date of publication of the final rule.
This proposed implementation timeframe simplifies FMCSR training
and enforcement because the Agency expects a large number of final
stage manufacturers supplying vehicles to motor carriers in the
category of vehicles with a gross vehicle weight rating greater than
4,536 kilograms (10,000 pounds).
FMCSA will require the ESC and AEB systems to be inspected and
maintained in accordance with Sec. 396.3.

X. Retrofitting

The Secretary has the statutory authority to promulgate safety
standards for commercial motor vehicles and equipment subsequent to
initial manufacture. The Secretary has delegated authority to NHTSA, in
coordination with FMCSA, to promulgate safety standards for commercial
motor vehicles and equipment subsequent to initial manufacture when the
standards are based upon and similar to an FMVSS.\190\
---------------------------------------------------------------------------

\190\ Sec. 101(f) of Motor Carrier Safety Improvement Act of
1999 (Pub. L. 106-159; Dec. 9, 1999). 49 CFR 1.95(c).
---------------------------------------------------------------------------

NHTSA considered, but decided against, proposing to require
retrofitting of in-service vehicles with GVWR greater than 4,536 kg
(10,000 lbs.) with AEB systems. NHTSA believes that retrofitting in-
service vehicles with AEB systems could be very complex and costly
because of the integration between an AEB system and the vehicles'
chassis, engine, and braking systems. There may be changes that would
have to be made to an originally manufactured vehicle's systems that
interface with an AEB system, such as plumbing for new air brake valves
and lines and a new electronic control unit for a revised antilock
braking system and a new electronic stability control system. NHTSA
might also have to develop and establish additional requirements to
ensure that AEB control components on in-service (used) vehicles are at
an acceptable level of performance for a compliance test of AEB. This
would be likely given the uniqueness of each vehicle's maintenance
condition, particularly for items such as tires and brake components,
which are foundational for AEB performance (and which are subject to
high demands of wear-and-tear).
Nonetheless, although this NPRM does not propose requiring heavy
vehicles to be equipped with AEB subsequent to initial manufacture,
NHTSA requests comment on the following issues related to retrofitting
to learn more about the technical and economic feasibility of a
retrofit requirement going forward.
The complexity, cost, and burdens of a requirement to
retrofit in-service vehicles with AEB.
The changes that would be needed to an originally
manufactured vehicle's systems that interface with an AEB system, such
as plumbing for new air brake valves and lines and a new electronic
control unit for a revised ABS and a new ESC system.
Approaches NHTSA could take to identify portions of the
on-road fleet to which a retrofit requirement could apply. For a
retrofitting requirement, should the requirement distinguish among in-
service vehicles based on the vehicles' date of manufacture? Is it
reasonable to assume that older in-service vehicles would have greater
challenges to meet a retrofit requirement? What should, for example,
the original manufacture date be of vehicles that should be subject to
a retrofit requirement?
Should there be provisions to ensure that the various
components related to AEB performance (e.g., brakes and tires) are at
an acceptable level of performance for a compliance test, given the
uniqueness of the maintenance condition for vehicles in service,
especially for items particularly subject to wear-and-tear (e.g., brake
components and tires)?
Relatedly, would it be warranted to vary the performance
requirements for retrofitted vehicles, so that the requirements would
be less stringent for used vehicles? If yes, what would be appropriate
level of stringency? If not, how can the requirements be adjusted for
in-service vehicles?
NHTSA requests comment on other options the agency could
take to identify portions of the on-road fleet to which a retrofit
requirement should apply. Are there other voluntary improvements that
heavy vehicle operators would consider in attaining the benefits
provided by AEB for their in-service vehicles?

XI. Summary of Estimated Effectiveness, Cost, Benefits, and Comparison
of Regulatory Alternatives

A. Crash Problem

NHTSA's assessment of available safety data indicates that between
2017 and 2019, an average of approximately 60,000 crashes occurred
annually in which a heavy vehicle rear-ended another vehicle. These
crashes resulted in an annual average of 388 fatalities, approximately
30,000 non-fatal injuries, and 84,000 property-damage-only vehicles.
Additionally, class 3-6 heavy vehicles were involved in approximately
17,000 rollover and loss of control crashes annually. These crashes
resulted in 178 fatalities, approximately 4,000 non-fatal injuries, and
13,000 property-damage-only vehicles annually. In total, these rear-
end, rollover, and loss of control crashes add up to 77,000 annually,
which represent 1.2 percent of all police-reported crashes and over 14
percent of all crashes involving heavy vehicles. In total, these
crashes resulted in 566 fatalities and 34,000 non-fatal injuries. These
crashes also damaged 97,000 vehicles in property-damage-only crashes.

B. AEB System Effectiveness

NHTSA evaluated the effectiveness of AEB indicates based on the
efficacy of the system in avoiding a rear-end crash. This relates to
the proposed requirement that a vehicle avoid an imminent rear-

[[Page 43225]]

end collision under a set of test scenarios. One method of estimating
effectiveness would be to perform a statistical analysis of real-world
crash data and observe the differences in statistics between heavy
vehicles equipped with AEB and those not equipped with AEB. However,
this approach is not feasible currently due to the low penetration rate
of AEB in the on-road vehicle fleet. Consequently, NHTSA estimated the
effectiveness of AEB systems using performance data from the agency's
vehicle testing. Effectiveness was assessed against all crash severity
levels collectively, rather than for specific crash severity levels
(i.e., minor injury versus fatal).
The AEB effectiveness estimates were derived from performance data
from four vehicles tested by NHTSA, and the agency is continuing its
effort to test a larger variety of vehicles to further evaluate AEB
system performance. These vehicles were subject to the same test
scenarios (stopped lead vehicle, slower-moving lead vehicle, and
decelerating lead vehicle) that are proposed in this notice, and
effectiveness estimates are based on each vehicle's capacity to avoid a
collision during a test scenario. For example, if a vehicle avoided
colliding with a stopped lead vehicle in four out of five test runs,
its effectiveness in that scenario would be 80 percent. The test
results for each vehicle were combined into an aggregate effectiveness
value by vehicle class range and crash scenario, as displayed in Table
17.

Table 17--AEB Effectiveness (%) by Vehicle Class Range and Crash Scenario
----------------------------------------------------------------------------------------------------------------
Stopped lead Slower-moving Decelerating lead
Vehicle class range vehicle lead vehicle vehicle
----------------------------------------------------------------------------------------------------------------
7-8.................................................... 38.5 49.2 49.2
3-6.................................................... 43.0 47.8 47.8
----------------------------------------------------------------------------------------------------------------

As shown in Table 17, after aggregating class 7 and class 8
together, AEB would avoid 38.5 percent of rear-end crashes for the
stopped lead vehicle scenario, and 49.2 percent of slower-moving and
decelerating lead vehicle target crashes. For class 3-6, AEB is 43.0
percent effective against stopped lead vehicle crashes and 47.8 percent
against slower-moving and decelerating lead vehicle target crashes.
These effectiveness values are the values used for assessing the
benefits of this proposed rule. Further detail on the derivation of AEB
effectiveness can be found in the PRIA accompanying this proposal.

C. ESC System Effectiveness

ESC effectiveness rates were adopted from those estimated in the
final regulatory impact analysis for the final rule implementing heavy
vehicle ESC requirements in FMVSS No. 136.\191\ In that final rule, a
range of ESC crash avoidance effectiveness was established for the
first-event rollover crashes but only a single-point estimate was
established for loss of control crashes. ESC was estimated to be 40 to
56 percent effective at preventing rollover crashes and 14 percent
effective at preventing loss-of-control crashes. For simplicity, and to
correspond with the single-point estimate for loss of control crashes,
the PRIA used the mid-point between the lower and upper bounds of the
estimated range as the effectiveness for rollovers.
---------------------------------------------------------------------------

\191\ Final Regulatory Impact Analysis, FMVSS No. 136 Electronic
Stability Control on Heavy Vehicles, June 2014, Docket No. NHTSA-
2015-0056.
---------------------------------------------------------------------------

The propensity for vehicles to experience rollover and loss-of-
control crashes is influenced by their body type and center of gravity,
and the implementation of ESC varies. ESC was estimated to be less
effective on class 7 and 8 vehicles than it was on light vehicles,
especially for rollover crashes.\192\ Vehicle characteristics for class
3 through 6 vehicles range between that of light trucks and vans and
class 7 and 8 vehicles, it would be plausible to assume that ESC
effectiveness would be between the effectiveness estimated in the FMVSS
No. 126 and FMVSS No. 136 final rules. Nevertheless, this NPRM uses the
effectiveness estimates from the FMVSS No. 136 final rule.
---------------------------------------------------------------------------

\192\ Dang, J. (July 2007) Statistical Analyzing of the
Effectiveness of Electronic Stability Control (ESC) Systems--Final
Report, DOT HS 810 794, Washington, DC, https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/810794.

Table 18--ESC Effectiveness (%) by Crash Scenario
------------------------------------------------------------------------
Loss of
Vehicle class range Rollover control
------------------------------------------------------------------------
3-6............................................. 48.0 14.0
------------------------------------------------------------------------

D. Avoided Crashes and Related Benefits

Considering the annual heavy vehicle rear-end, rollover, and loss
of control crashes, as well as the effectiveness of AEB and ESC at
avoiding these crashes, the proposed rule would prevent an estimated
19,118 crashes, 155 fatalities, and 8,814 non-fatal injuries annually.
In addition, the proposed rule would eliminate an estimated 24,828
PDOVs annually. The benefit estimates include assumptions that likely
result in the underestimation of the benefits of this proposal because
it only reflects the benefits from crash avoidance. That is, the
benefits only reflect those resulting from crashes that are avoided as
a result of the AEB and ESC performance proposed. It is likely that AEB
will also reduce the severity of crashes that are not prevented. Some
of these crashes may include fatalities and significant injuries that
will be prevented or mitigated by AEB.
Table 19 tabulates these benefits in two ways, one by vehicle class
and one by technology. These benefits are measured for the portion of
the vehicle fleet that has not voluntarily adopted AEB prior to the
NPRM. These benefits also assume reduced performance under dark or
hazardous weather conditions. The estimated annual benefits would be
the undiscounted lifetime benefits once the proposal is fully
implemented (four years after publication of a final rule). The
undiscounted lifetime benefits for each new model year of vehicles
would equal the annual benefits of the on-road fleet when that fleet
has been fully equipped with this technology. The actual annual
benefits will increase each year as the on-road vehicle fleet is
replaced with vehicles that would be subject to the proposed
requirements.

[[Page 43226]]

Table 19--Undiscounted Estimated Annual Benefits of the Proposed Rule
----------------------------------------------------------------------------------------------------------------
Non-fatal
Crashes Fatalities injuries PDOVs
----------------------------------------------------------------------------------------------------------------
By Vehicle Class:
Class 7-8................................... 5,691 40 2,822 7,958
Class 3-6................................... 13,427 115 5,992 16,870
---------------------------------------------------------------
Total................................... 19,118 155 8,814 24,828
By Technology:
AEB......................................... 16,224 106 8,058 22,713
ESC......................................... 2,894 49 756 2,115
---------------------------------------------------------------
Total................................... 19,118 155 8,814 24,828
----------------------------------------------------------------------------------------------------------------

E. Technology Costs

The AEB system is estimated to cost $396 per vehicle. The unit cost
includes all the components, labor cost for training customers, tuning
the system to ensure the performance of AEB, and the AEB malfunction
telltale. The component unit costs were based on the agency's 2018
weight and teardown study, which accounted for scale efficiencies in
production and labor.\193\ The cost for an ESC system would range from
$320 to $687, which was calculated by adjusting the assumed unit cost
for ESC in the FMVSS No. 136 final rule for inflation.\194\ Therefore,
for vehicles that need both AEB and ESC, the total unit cost would
range from $716 to $1,083 per affected vehicle.\195\ The total number
of affected vehicles including trucks and buses are estimated to be
569,792 units annually: 164,405 units for class 7-8 and 405,387 units
for class 3-6 vehicles. The total cost corresponding to the estimated
annual benefits is estimated to be $353 million ($288 million for class
7-8 and $65 million for class 3-6). The affected vehicle units were
based on the 10 year average of units sold between 2011 and 2020.\196\
---------------------------------------------------------------------------

\193\ ``Cost and Weight Analysis of Heavy Vehicle Forward
Collision Warning (FCW) and Automatic Emergency Braking (AEB)
Systems for Heavy Trucks,'' September 27, 2018, Contract number:
DTNH2216D00037, Task Order: DTNH2217F00147.
\194\ Final Regulatory Impact Analysis, FMVSS No. 136 Electronic
Stability Control on Heavy Vehicles, June 2014, Docket No. NHTSA-
2015-0056.
\195\ AEB and ESC unit cost estimates are the additional
component costs for the vehicles without the systems. Specifically,
AEB cost is the additional hardware to those vehicles that already
had ESC.
\196\ Due to data constraints, the average is only available for
trucks and school buses. The annual sales volume for motorcoaches
and transit buses was based on the agency's estimate for earlier
final rules and other sources. Please consult Appendix B of the PRIA
for details.
---------------------------------------------------------------------------

F. Monetized Benefits

Table 20 summarizes the primary benefit cost estimates, which
include the annual total cost, total monetized savings, cost per
equivalent life saved, and net benefits of the proposed rule under
three and seven percent discount rates. Monetized savings are measured
by comprehensive costs, which include the tangible costs of reducing
fatalities and injuries such as savings from medical care, emergency
services, insurance administration, workplace costs, legal costs,
congestion and property damage, lost productivity as well as
nontangible cost of quality life lost. The nontangible cost components
were based on the value of statistical life of $11.8 million.\197\
---------------------------------------------------------------------------

\197\ Departmental Guidance on Valuation of a Statistical Life
in Economic Analysis, Effective Date: Friday, March 4, 2022, https://www.transportation.gov/office-policy/transportation-policy/revised-departmental-guidance-on-valuation-of-a-statistical-life-in-economic-analysis.
---------------------------------------------------------------------------

The proposed rule would generate a net benefit of $1.81 billion to
$2.58 billion, annually under 3 and 7 percent discount rates. The
proposed rule would be cost-effective given that the highest estimated
net cost per fatal equivalent would be $0.50 million, a value less than
$12.2 million (the comprehensive cost of a fatality). The negative net
cost per fatal equivalent for the 3 percent discount rate indicates
that the savings from reducing traffic congestion and property damage
is greater than the total cost of the proposed rule. Net benefits are
likely to be even higher given that the estimates only include benefits
from crashes prevented by AEB, but do not include benefits from crashes
for which AEB mitigates the severity of, but does not prevent.

Table 20--Estimated Annual Cost, Monetized Benefits, Cost-Effectiveness, and Net Benefits of the Proposed Rule
[2021 dollars in millions]
----------------------------------------------------------------------------------------------------------------
Net cost per
Discount rates Annual cost * Monetized savings fatal equivalent Net benefits
----------------------------------------------------------------------------------------------------------------
3 Percent........................... $353.3 $2,937.0 **-$0.12 $2,583.7
7 Percent........................... 353.3 2,160.4 0.50 1,807.1
----------------------------------------------------------------------------------------------------------------
* Annual cost is not discounted because it is paid at vehicle purchase.
** At a three percent discount rate, savings from reduced traffic congestions and property damages outweigh the
cost, resulting in negative net cost per equivalent life. The negative value indicates cost-effectiveness.

G. Alternatives

NHTSA has identified and assessed alternatives to the preferred
alternative set forth in the proposed regulatory text. The agency
considered two primary alternatives to the proposed rule.
The first alternative would not require AEB or ESC on vehicles not
currently subject to FMVSS No. 136. Eliminating the requirement would
reduce the burden on heavy vehicle manufacturers associated with
installing AEB and ESC on vehicles with different body types, but would
result in significantly fewer

[[Page 43227]]

safety benefits and lives saved. A summary of the costs, benefits, and
cost-effectiveness associated with Alternative 1 is in Table 21.

Table 21--Discounted Benefits of Alternative 1
[Millions of 2021$]
----------------------------------------------------------------------------------------------------------------
Net cost per
Annual cost * Monetized savings fatal equivalent Net benefits
----------------------------------------------------------------------------------------------------------------
3 Percent Discount.................. $65.10 $874.59 **-$1.00 $809.50
7 Percent Discount.................. 65.10 662.23 -0.66 597.10
----------------------------------------------------------------------------------------------------------------
* Annual cost is not discounted because it is paid at vehicle purchase.
** At a three percent discount rate, savings from reduced traffic congestions and property damages outweigh the
cost, resulting in negative net cost per equivalent life. The negative value indicates cost-effectiveness.

The second alternative would require all class 3-6 heavy vehicles
to have AEB and ESC within four years, as with the primary agency
proposal. However, this alternative would include a one-year phase-in
period beginning three years after publication of the final rule in
which 50 percent of class 3-6 vehicles would be required to install AEB
and ESC. This alternative was considered because it has the potential
to save more lives sooner. This alternative would have the same annual
cost, savings, net cost per fatal equivalent, and net benefits as the
primary proposal. However, this alternative would result in added
benefits from vehicles manufactured in the phase-in period. The
estimated total additional benefits associated with alternative 2 above
the primary estimate are summarized in Table 22.

Table 22--Discounted Additional Benefits of Alternative 2 Above the
Primary Proposal
[Millions of 2021$]
------------------------------------------------------------------------
Percent discount 3 7
------------------------------------------------------------------------
Net Additional Benefit.......................... $830.5 $566.4
------------------------------------------------------------------------

Detailed benefit-cost calculations of these alternatives are
discussed in the PRIA. The agency seeks comment on the feasibility of
the second alternative.
Because of the significant safety benefits that accrue by including
Class 3-6 vehicles, and to allow time for the Class 3-6 vehicle
manufactures to optimize implementations of both ESC and AEB into their
vehicles, the agency decided not to select either alternative.

XII. Regulatory Notices and Analyses

Executive Orders 12866, 13563, and 14094 and DOT Regulatory Policies
and Procedures

NHTSA and FMCSA have considered the impact of this rulemaking
action under Executive Order 12866, as amended by Executive Order
14094, Executive Order 13563, and the Department of Transportation's
regulatory procedures. This rulemaking is considered significant under
section 3(f)(1) of Executive Order 12866, as amended, and was reviewed
by the Office of Management and Budget under that Executive Order.
NHTSA and FMCSA have prepared a preliminary regulatory impact analysis
(PRIA) that assesses the cost and benefits of this proposed rule. The
benefits, costs and other impacts of this NPRM are discussed in the
prior section.

Regulatory Flexibility Act

Pursuant to the Regulatory Flexibility Act of 1980, Public Law 96-
354, 94 Stat. 1164 (5 U.S.C. 601 et seq., as amended), whenever an
agency is required to publish an NPRM or a final rule, it must prepare
and make available for public comment a regulatory flexibility analysis
that describes the effect of the rule on small entities (i.e., small
businesses, small not-for-profit organizations, and small governmental
jurisdictions). I certify that this NPRM would not have a significant
economic impact on a substantial number of small entities.
NHTSA's proposal would directly affect manufacturers of class 3-
through 8 trucks, buses, and multipurpose passenger vehicles. Of the
more than 20 companies who are sole manufacturers or first-stage
manufacturers of class 3 through 8 vehicles in the United States, NHTSA
found two companies (Proterra and Workhorse Group, Inc.) that qualify
as a small entities.\198\ Table 23. Below show the list of heavy duty
truck manufacturers.
---------------------------------------------------------------------------

\198\ NHTSA researched MD and HD vehicle manufacturing companies
and found their estimated number of employees and annual revenue (as
of Dec 2022) from the following sources: zoominfo.com,
macrotrends.net, zippia.com, statista.com, and linkedin.com.

Table 23--Heavy Duty Truck Manufacturers
----------------------------------------------------------------------------------------------------------------
Annual revenue
Type Company # Employees (millions) Notes
----------------------------------------------------------------------------------------------------------------
Trucks.......................... Autocar company.... 487 $126 Parent Company: GVW
Group.
Brightdrop......... 252 138 Parent Company: GM.
Ford............... 186,000 158,060 ...................
GM................. 167,000 156,700 ...................
International...... 2,760 721 Parent Company:
Navistar.
Freightliner....... 15,000 450 Parent Company:
Daimler.
Hendrickson 6,000 1,600 ...................
International.
Mack............... 2,000 671 Parent Company:
Volvo.
Navistar........... 14,500 3,900 ...................
Oshkosh Corp....... 15,000 8,300 ...................
PACCAR............. 31,100 28,800 Subsidiaries:
Kenworth,
Peterbilt.
Ram................ 200,000 180,000 Parent Company:
Stellantis.

[[Page 43228]]

Shyft Group........ 4,200 1,000 ...................
Western Star....... 3,221 680 Parent Company:
Daimler.
Workhorse.......... 331 5 Small Business.
Buses........................... Bluebird........... 1,702 726 ...................
Forest River....... 11,000 3,300 Parent Company:
Berkshire
Hathaway.
Gillig............. 900 267 Parent Company:
Henry Crown & Co.
IC Bus............. 219 44 Parent Company:
Navistar.
Nikola............. 1,500 51 ...................
Proterra........... 938 247 Small Business.
REV group.......... 6,800 2,300 Subsidiary: El
Dorado.
Thomas Built Buses. 1,276 288 Parent Company:
Daimler.
----------------------------------------------------------------------------------------------------------------

Workhorse Group, Inc. currently has about 330 employees. Its
vehicles are already equipped with ESC and AEB and are unlikely to be
affected by this proposal. Proterra is a manufacturer of large electric
transit buses and falls into the small business threshold with about
9,400 employees. Although its vehicles are not currently equipped with
AEB, its vehicles sell for approximately $750,000. With such a high
sale price, NHTSA considers the effect of this rule on the price of the
vehicle to be de minimis. Accordingly, NHTSA has concluded that this
proposal would not have a significant economic impact upon these small
entities. However, NHTSA seeks comment on this conclusion.
Final stage manufacturers are also affected by this proposal, and
final stage manufacturers would be considered small entities. According
to the U.S. Census, there are 570 small businesses in body
manufacturing for light, medium, and heavy-duty classes.\199\ This
proposal likely would affect a substantial number of final stage
manufacturers that are small businesses. It is NHTSA's understanding
that these small entities rarely make modifications to a vehicle's
braking system and instead rely upon the pass-through certification
provided by the first-stage manufacturer, which is not typically a
small business.. More information about multi-stage vehicle
manufacturing can be found in section VI.E of this proposal.
Additionally, this proposal would further accommodate final-stage
manufacturers by providing them an additional year before compliance is
required. Therefore, NHTSA does not believe at this time that the
impacts of this proposal on small entities would be significant.
---------------------------------------------------------------------------

\199\ 2020 SUSB Annual Data Tables by Establishment Industry,
``U.S. and states, NAICS, detailed employment sizes.'' https://www.census.gov/data/tables/2020/econ/susb/2020-susb-annual.html.
---------------------------------------------------------------------------

This rule may also affect purchasers of class 3 through 8 vehicles.
It is assumed that the incremental costs of this proposal would be
passed on to these purchasers. Class 7 through 8 vehicles are primarily
purchased by motor carriers, an industry composed of approximately
757,652 interstate, intrastate, and hazardous materials motor carriers,
in which over ninety percent of its companies (687,139) are considered
small.\200\ Class 3-6 vehicles consisting of work pickup trucks, small
buses, and moving/cargo vans are purchased and utilized in industries
where small businesses are not uncommon as well. It is not known
precisely how frequently small businesses purchase new vehicles
(instead of used vehicles) affected by the proposed rule, however,
small entities usually have the option to finance or lease these
vehicles to mitigate financial burden by spreading out cost over time.
Table 24 below shows a list of industries, where small businesses may
be affected by the proposed rule.
---------------------------------------------------------------------------

\200\ Assume a motor carrier of 10 or less power units is
considered a small entity, which is very conservative given an SBA
size standard of $30 million in annual revenue. 2022 Pocket Guide to
Large Truck and Bus Statistics (December 2022), Federal Motor
Carrier Safety Administration, p.13.

Table 24--SBA Size Standards of Indirectly Affected Industries
----------------------------------------------------------------------------------------------------------------
Size standards in
NAICS Code NAICS Industry description millions of
dollars
----------------------------------------------------------------------------------------------------------------
484110....................................... General Freight Trucking, Local............... 30
484122....................................... General Freight Trucking, Long-Distance, 30
Truckload.
484122....................................... General Freight Trucking, Long-Distance, Less 38
Than Truckload.
484210....................................... Used Household and Office Goods Moving........ 30
484220....................................... Specialized Freight (except Used Goods) 30
Trucking, Local.
484230....................................... Specialized Freight (except Used Goods) 30
Trucking, Long-Distance.
485113....................................... Bus and Other Motor Vehicle Transit Systems... 28.5
485210....................................... Interurban and Rural Bus Transportation....... 28
485410....................................... School & Employee Bus Transportation.......... 26.5
485510....................................... Charter Bus Industry.......................... 17
485991....................................... Special Needs Transportation.................. 16.5
488410....................................... Motor Vehicle Towing.......................... 8
----------------------------------------------------------------------------------------------------------------

[[Page 43229]]

FMCSA's proposed requirement would ensure that the benefits
resulting from CMVs equipped with AEBs are sustained through proper
maintenance and operation. The cost of maintaining AEB systems is
minimal and may be covered by regular annual maintenance. Therefore,
FMCSA does not expect this requirement to have a significant economic
impact on a substantial number of small entities.
Additional information concerning the potential impacts of this
proposal on small businesses is presented in the PRIA accompanying this
proposal. The agencies seek comment on the effects this NPRM would have
on small businesses.

National Environmental Policy Act

The National Environmental Policy Act of 1969 (NEPA) \201\ requires
Federal agencies to analyze the environmental impacts of proposed major
Federal actions significantly affecting the quality of the human
environment, as well as the impacts of alternatives to the proposed
action.\202\ The Council on Environmental Quality (CEQ)'s NEPA
implementing regulations direct federal agencies to determine the
appropriate level of NEPA review for a proposed action; an agency can
determine that a proposed action normally does not have significant
effects and is categorically excluded,\203\ or can prepare an
environmental assessment for a proposed action ``that is not likely to
have significant effects or when the significance of the effects is
unknown.'' \204\ When a Federal agency prepares an environmental
assessment, CEQ's NEPA implementing regulations require it to (1)
``[b]riefly provide sufficient evidence and analysis for determining
whether to prepare an environmental impact statement or a finding of no
significant impact;'' and (2) ``[b]riefly discuss the purpose and need
for the proposed action, alternatives . . . , and the environmental
impacts of the proposed action and alternatives, and include a listing
of agencies and persons consulted.'' \205\
---------------------------------------------------------------------------

\201\ 42 U.S.C. 4321-4347.
\202\ 42 U.S.C. 4332(2)(C).
\203\ 40 CFR 1501.4.
\204\ 40 CFR 1501.5(a).
\205\ 40 CFR 1501.5(c).
---------------------------------------------------------------------------

As discussed further below, FMCSA has determined that its proposed
action is categorically excluded from further analysis and
documentation in accordance with FMCSA Order 5610.1.\206\ NHTSA
determined that there is no similarly applicable categorical exclusion
for its proposed action and has therefore determined that it is
appropriate to prepare a Draft Environmental Assessment (EA). The
preamble provides additional information about the distinction between
NHTSA and FMCSA's proposed requirements based on each agency's
statutory authority.
---------------------------------------------------------------------------

\206\ 69 FR 9680 (Mar. 1, 2004).
---------------------------------------------------------------------------

This section serves as NHTSA's Draft EA. In this Draft EA, NHTSA
outlines the purpose and need for the proposed rulemaking, a reasonable
range of alternative actions the agency could adopt through rulemaking,
and the projected environmental impacts of these alternatives.
Purpose and Need
This NPRM preamble and the accompanying PRIA set forth the purpose
of and need for this action. The preamble and PRIA outline the safety
need for this proposal, in particular to address safety problems
associated with heavy vehicles, i.e., vehicles with a GVWR greater than
4,536 kilograms (10,000 pounds). These heavy vehicles, also referred to
as Class 3-8 vehicles,\207\ include single unit straight trucks,
combination trucks, truck tractors, motorcoaches, transit buses, school
buses, and certain pickup trucks. An annualized average of 2017 to 2019
data from NHTSA's FARS and CRSS shows heavy vehicles were involved in
around 60,000 rear-end crashes in which the heavy vehicle was the
striking vehicle annually, which represents 11 percent of all crashes
involving heavy vehicles.\208\ These rear-end crashes resulted in 388
fatalities annually, which comprises 7.4 percent of all fatalities in
heavy vehicle crashes. These crashes resulted in approximately 30,000
injuries annually, or 14.4 percent of all injuries in heavy vehicle
crashes, and 84,000 damaged vehicles with no injuries or fatalities.
Considering vehicle size, approximately half of the rear-end crashes,
injuries, and fatalities resulting from rear-end crashes where the
heavy vehicle was the striking vehicle involved vehicles with a GVWR
above 4,536 kilograms (10,000 pounds) up to 11,793 kilograms (26,000
pounds). Similarly, half of all rear-end crashes and the fatalities and
injuries resulting from those crashes where the heavy vehicle was the
striking vehicle involved vehicles with a GVWR of greater than 11.793
kilograms (26,000 pounds).
---------------------------------------------------------------------------

\207\ Class is a vehicle classification system used by the
Federal Highway Administration of Department of Transportation to
categorize vehicles into 8 Classes based on vehicle size, weight,
and number of wheels. The following lists the GVWR for Class 3-8
heavy vehicles. A complete vehicle class categorization table is
included in 49 CFR part 565.
Class GVWR
Class 3: 4,536-6,350 kg (10,001-14,000 pounds)
Class 4: 6,351-7,257 kg (14,001-16,000 pounds)
Class 5: 7,258-8,845 kg (16,001-19,500 pounds)
Class 6: 8,846-11,793 kg (19,501-26,000 pounds)
Class 7: 11,794-14,969 kg (26,001-33,000 pounds)
Class 8: 14,969 kg (33,001 pounds) and above
\208\ These rear-end crashes are cases where the heavy vehicle
was the striking vehicle.
---------------------------------------------------------------------------

To address this safety need, NHTSA proposes to adopt a new FMVSS to
require AEB systems on certain heavy vehicles.\209\ Current AEB systems
use radar and camera-based sensors or combinations thereof and build
upon older FCW-only systems. An FCW-only system provides an alert to a
driver of an impending rear-end collision with a lead vehicle to induce
the driver to take action to avoid the crash but does not automatically
apply the brakes. This proposal would require both FCW and AEB systems.
For simplicity, when referring to AEB systems in general, this proposal
is referring to both FCW and AEB unless the context suggests otherwise.
NHTSA also proposes to amend FMVSS No. 136 to require nearly all heavy
vehicles to have an ESC system that meets the equipment requirements,
general system operational capability requirements, and malfunction
detection requirements of FMVSS No. 136. In addition to requiring
certain heavy vehicles be equipped with AEB/ESC, the proposed rule
requires the heavy vehicles to be able to avoid a collision in various
rear-end crash scenarios at different speeds.
---------------------------------------------------------------------------

\209\ Some heavy vehicles are excluded from the proposed rule.
These include those vehicles that are excluded from FMVSS No. 121
and FMVSS No. 136.
---------------------------------------------------------------------------

As explained earlier in this preamble, the AEB system improves
safety by using various sensor technologies and sub-systems that work
together to detect when the vehicle is in a crash imminent situation,
to automatically apply the vehicle brakes if the driver has not done
so, or to apply more braking force to supplement the driver's braking,
thereby detecting and reacting to an imminent crash. This proposed rule
is anticipated to address the safety need by mitigating the amount of
fatalities, non-fatal injuries, and property damage that would result
from crashes that could potentially be prevented or mitigated because
of AEB and ESC. This proposed rule is expected to substantially
decrease risks associated with rear-end, rollover, and loss of control
crashes.
This NPRM follows NHTSA's 2015 grant of a petition for rulemaking
from the Truck Safety Coalition, the Center for Auto Safety, Advocates
for Highway

[[Page 43230]]

and Auto Safety and Road Safe America, requesting that NHTSA establish
a safety standard to require AEB on certain heavy vehicles. This NPRM
also responds to a mandate under the Bipartisan Infrastructure Law,
enacted as the Infrastructure Investment and Jobs Act, directing the
Department to prescribe an FMVSS that requires heavy commercial
vehicles with FMVSS-required ESC systems to be equipped with an AEB
system, and also promotes DOT's January 2022 National Roadway Safety
Strategy to initiate a rulemaking to require AEB on heavy trucks. This
NPRM also proposes Federal Motor Carrier Safety Regulations requiring
the ESC and AEB systems to be on during vehicle operation.
Alternatives
NHTSA has considered three regulatory alternatives for the proposed
action and a ``no action alternative.'' Under the no action
alternative, NHTSA would not issue a final rule requiring that vehicles
be equipped (installation standards) with systems that meet minimum
specified performance standards, and manufacturers would continue to
add these systems voluntarily. However, since the BIL directs NHTSA to
promulgate a rule that would require heavy vehicles subject to FMVSS
No. 136 to be equipped with an AEB system, the no action alternative is
not a permissible option. The proposed standard (the preferred
alternative) requires specific AEB/ESC installation and performance
standards for certain Class 3-8 heavy vehicles with a two-tiered phase-
in schedule based on whether the heavy vehicle is currently subject to
FMVSS No. 136. Alternative 1, which is considered less stringent than
the preferred alternative, would set AEB/ESC installation and
performance standards only for vehicles currently subject to FMVSS No.
136. Alternative 2, which is considered more stringent than the
preferred alternative, would require a more aggressive phase-in
schedule for the AEB/ESC installation requirements for Class 3-6 heavy
vehicles.
Although these regulatory alternatives differ in phase-in schedule
and heavy vehicle Class applicability, the functional AEB/ESC
installation and performance requirements would be the same. Please see
the preamble and PRIA Chapter 11, Regulatory Alternatives, for more
information about the preferred alternative and other regulatory
alternatives, and the proposed standards' requirements.
Environmental Impacts of the Proposed Action and Alternatives
Based on the purpose and need for the proposed action and the
regulatory alternatives described above, the primary environmental
impacts that could potentially result from this rulemaking are
associated with greenhouse gas (GHG) emissions and air quality,
socioeconomics, public health and safety, solid waste/property damage/
congestion, and hazardous materials.\210\ Consistent with CEQ
regulations and guidance, this EA discusses impacts in proportion to
their potential significance. The effects of the proposed rulemaking
that were analyzed further are summarized below.
---------------------------------------------------------------------------

\210\ NHTSA anticipates that the proposed action and
alternatives would have negligible or no impact on the following
resources and impact categories, and therefore has not analyzed them
further: topography, geology, soils, water resources (including
wetlands and floodplains), biological resources, resources protected
under the Endangered Species Act, historical and archeological
resources, farmland resources, environmental justice, and Section
4(f) properties.
---------------------------------------------------------------------------

Greenhouse Gas Emissions and Air Quality
NHTSA has previously recognized that additional weight required by
FMVSS could potentially negatively impact the amount of fuel consumed
by a vehicle, and accordingly result in GHG emissions or air quality
impacts from criteria pollutant emissions.\211\ Atmospheric GHGs affect
Earth's surface temperature by absorbing solar radiation that would
otherwise be reflected back into space. Carbon dioxide (CO2)
is the most significant GHG resulting from human activity. Motor
vehicles emit CO2 as well as other GHGs, including methane
and nitrous oxides, in addition to criteria pollutant emissions that
negatively affect public health and welfare.
---------------------------------------------------------------------------

\211\ Criteria pollutants is a term used to describe the six
common air pollutants for which the Clean Air Act (CAA) requires the
Environmental Protection Agency (EPA) to set National Ambient Air
Quality Standards (NAAQS). EPA calls these pollutants criteria air
pollutants because it regulates them by developing human health-
based or environmentally based criteria (i.e., science-based
guidelines) for setting permissible levels.
---------------------------------------------------------------------------

Additional weight added to a vehicle, like added hardware from
safety systems, can potentially cause an increase in vehicle fuel
consumption and emissions. NHTSA analyzed in PRIA Chapter 9.1,
Technology Unit Costs and Added Weights, the cost associated with
meeting the performance requirements in the proposed rule, including
the potential weight added to the vehicle. An AEB system for heavy
vehicles requires the following hardware: sensors (radar mounted at
front bumper and, in some cases, camera located at top, inside portion
of windshield), control units (electronic control unit), display (in
some cases integrated with existing dash cluster, in other cases, a
separate display), associated wiring harnesses, mounting hardware
specific to FCW/AEB system, and other materials and scrap (for
electronic parts, this category includes labels, soldering materials,
flux, and fasteners).\212\ Although AEB and ESC have some shared system
components, NHTSA also estimated that a limited amount of additional
hardware would be required for ESC systems depending on the vehicle
class, including accelerometers, yaw rate sensors, and steer angle
sensors.\213\ Based on a study conducted for NHTSA on the cost and
weight of heavy vehicle FCW and AEB systems,\214\ NHTSA concluded that
the added weight for the installation of AEB is estimated to be up to
3.10 kg (~ 7 lbs) and AEB and ESC combined is up to 6.70 kg (~ 15 lbs).
These weights are considered negligible compared to the 4,536 kg
(10,000 lbs) or greater curb weight of Class 3-8 vehicles. NHTSA
tentatively concluded in the PRIA that the proposed rule is not
expected to impact the fuel consumption of Class 3-8 vehicles, and
therefore none of the regulatory alternatives would be presumed to
result in GHG or criteria pollutant impacts.
---------------------------------------------------------------------------

\212\ PRIA, at 141.
\213\ Final Regulatory Impact Analysis, FMVSS No. 136,
Electronic Stability Control Systems on Heavy Vehicles; Docket No.
NHTSA-2015-0056-0002, at VI-5.
\214\ Department of Transportation National Highway Traffic
Safety Administration Office of Acquisition Management (NPO-320)
West Building 51-117 1200 New Jersey Avenue SE Washington, DC 20590
Contract Number: DTNH2216D00037 Task Order: DTNH2217F00147 Cost and
Weight Analysis of Heavy Vehicle Forward Collision Warning (FCW) and
Automatic Emergency Braking (AEB) Systems for Heavy Trucks Ricardo
Inc. Detroit Technical Center Van Buren Twp., MI 48111 USA September
27, 2018.
---------------------------------------------------------------------------

NHTSA also analyzed this action for purposes of the Clean Air Act
(CAA)'s General Conformity Rule.\215\ The

[[Page 43231]]

General Conformity Rule does not require a conformity determination for
Federal actions that are ``rulemaking and policy development and
issuance,'' such as this action.\216\ Therefore, NHTSA has determined
it is not required to perform a conformity analysis for this action.
---------------------------------------------------------------------------

\215\ Section 176(c) of the CAA, codified at 42 U.S.C. 7506(c);
To implement CAA Section 176(c), EPA issued the General Conformity
Rule (40 CFR part 51, subpart W and part 93, subpart B). Pursuant to
the CAA, the U.S. Environmental Protection Agency (EPA) has
established a set of National Ambient Air Quality Standards (NAAQS)
for the following criteria pollutants: carbon monoxide (CO),
nitrogen dioxide (NO2), ozone, particulate matter (PM)
less than 10 micrometers in diameter (PM10), PM less than
2.5 micrometers in diameter (PM2.5), sulfur dioxide
(SO2), and lead (Pb). EPA requires a ``conformity
determination'' when a Federal action would result in total direct
and indirect emissions of a criteria pollutant or precursor
originating in nonattainment or maintenance areas equaling or
exceeding the emissions thresholds specified in 40 CFR 93.153(b)(1)
and (2).
\216\ 40 CFR 93.153(c)(2)(iii).
---------------------------------------------------------------------------

Socioeconomics
The socioeconomic impacts of the proposed rule would be primarily
felt by heavy vehicle and equipment manufacturers, heavy vehicle
drivers, and other road users that would otherwise be killed or injured
as a result of heavy vehicle crashes. NHTSA conducted a detailed
assessment of the economic costs and benefits of establishing the new
rule in its PRIA. The main economic benefits come primarily from the
reduction in fatalities and non-fatal injuries (safety benefits).
Reductions in the severity of heavy vehicle crashes would be
anticipated to have corresponding reductions in costs for medical care,
emergency services, insurance administrative costs, workplace costs,
and legal costs due to the fatalities and injuries avoided. Other
socioeconomic factors discussed in the PRIA that would affect these
parties include quantified property damage savings, and additional
quantified and unquantified impacts like less disruptions to commodity
flow and improved traffic conditions. Most of these socioeconomic
benefits are related to public health and safety and are discussed in
more detail below.

Table 25--Comparison of Regulatory Alternatives
[2021 dollars]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Net cost per equivalent live saved Net benefits
Regulatory option Relative to the proposed rule ---------------------------------------------------------------------------
3% 7% 3% 7%
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed Rule............................... .............................. -$118,922 $496,746 $2,583,652,432 $1,807,064,498
--------------------------------------------------------------------------------------------------------------------------------------------------------
Alternative 1: AEB Requirements only for Less Stringent................ -1,003,884 -662,217 809,485,467 597,125,719
Class 7-8.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Alternative 2: More Aggressive Phase in More Stringent................ -118,922 496,746 2,583,652,432 1,807,064,498
Schedule for Class 3-6.
--------------------------------------------------------------------------------------------------------------------------------------------------------

The total annual cost, considering the implementation of both AEB
and ESC technologies proposed in this rule, is estimated to be $353
million. The proposed rule would generate a net benefit of $2.58 to
$1.81 billion, annually under 3 and 7 percent discount rates. The
proposed rule would be cost-effective given that the highest estimated
net cost per fatal equivalent would be $0.50 million. Maintenance costs
are considered de minimis and therefore not included in the cost
estimate. Please see PRIA for additional information about the annual
cost, monetized benefits, cost-effectiveness, and net benefits of this
proposal.
Public Health and Safety
The affected environment for public health and safety includes
roads, highways and other driving locations used by heavy vehicle
drivers, drivers and passengers in light vehicles and other motor
vehicles, and pedestrians or other individuals who could be injured or
killed in crashes involving the vehicles regulated by the proposed
action. In the PRIA, the agency determined the impacts on public health
and safety by estimating the reduction in fatalities and injuries
resulting from the decreased crash severity due to the use of AEB
systems under the regulatory alternatives. Under the proposed standard
(the preferred alternative), it is expected that the addition of a
requirement for specific AEB/ESC installation and performance standards
for certain Class 3-8 heavy vehicles with a two-tiered phase-in
schedule, would result each year in 151 to 206 equivalent lives saved.
Under Alternative 1, it is expected that the addition of a less
stringent requirement that would set AEB/ESC installation and
performance standards only for Class 7-8 heavy vehicles, with the same
phase-in schedule as the preferred alternative, would result each year
in 45 to 60 equivalent lives saved. Under Alternative 2, it is expected
that the addition of a more stringent requirement that would require a
more aggressive phase-in schedule for the AEB/ESC installation
requirements for Class 3-6 heavy vehicles, would result in 94 to 128
equivalent lives saved in 2024 and 151 to 206 equivalent lives saved in
2025 onwards. The PRIA discusses this information in further detail.
Solid Waste/Property Damage/Congestion
Vehicle crashes can generate solid wastes and release hazardous
materials into the environment. The chassis and engines, as well as
associated fluids and components of automobiles and the contents of the
vehicles, can all be deemed waste and/or hazardous materials. Solid
waste can also include damage to the roadway infrastructure, including
road surface, barriers, bridges, and signage. Hazardous materials are
substances that may pose a threat to public safety or the environment
because of their physical, chemical, or radioactive properties when
they are released into the environment, in this case as a result of a
crash. Vehicle crashes also generate socioeconomic and environmental
effects from congestion as engines idle while drivers are caught in
traffic jams and slowdowns, in particular from wasted fuel and the
resulting increased greenhouse gas emissions.\217\
---------------------------------------------------------------------------

\217\ Blincoe, L.J., Miller, T.R., Zaloshnja, E., & Lawrence,
B.A. (2015, May). The economic and societal impact of motor vehicle
crashes, 2010. (Revised) (Report No. DOT HS 812 013). Washington,
DC: National Highway Traffic Safety Administration.
---------------------------------------------------------------------------

The proposal is projected to reduce the amount and severity of
heavy vehicle crashes, and therefore is expected to reduce the quantity
of solid waste, hazardous materials, and other property damage
generated by vehicle crashes in the United States, in addition to
reducing the traffic congestion that occurs as a consequence of a
crash. Less solid waste translates into cost and environmental savings
from reductions in the following areas: (1) transport of waste
material, (2) energy required for recycling efforts, and (3) landfill
or

[[Page 43232]]

incinerator fees. Less waste will result in beneficial environmental
effects through less GHG emissions used in the transport of it to a
landfill, less energy used to recycle the waste, less emissions through
the incineration of waste, and less point source pollution at the scene
of the crash that would result in increased emissions levels or
increased toxins leaking from the crashed vehicles into the surrounding
environment. Similarly, as mentioned above, less congestion translates
into economic and environmental benefits from fuel savings and reduced
GHG emissions, in addition to benefits from the time that drivers are
not caught in additional traffic congestion.
As discussed in the PRIA, NHTSA's monetized benefits are calculated
by multiplying the number of non-fatal injuries and fatalities
mitigated by their corresponding ``comprehensive costs.'' The
comprehensive costs include economic costs that are external to the
value of a statistical life (VSL) costs, such as emergency management
services or legal costs, and congestion costs. NHTSA calculated the
monetized benefits attributable to reduced traffic congestion and
property damage in the PRIA accompanying this proposed rule for the
proposed action and the regulatory alternatives. As shown in Table 26,
the monetized benefits from reduced traffic congestion and property
damage increase as the regulatory alternatives increase the heavy
vehicle classes covered by the proposal and the proposal's phase-in
year. Please see PRIA for additional information about the
comprehensive cost values used in this proposal.

Table 26--Congestion and Property Damage Savings
----------------------------------------------------------------------------------------------------------------
Alternative 1 Preferred alternative Alternative 2
----------------------------------------------------------------------------------------------------------------
3% Discount 7% Discount 3% Discount 7% Discount 3% Discount 7% Discount
----------------------------------------------------------------------------------------------------------------
$125,337,423......... $94,904,159 $377,815,690 $278,309,156 2024: 2024:
$243,518,740. $180,753,307.
2025 Onwards: 2025 Onwards:
$377,815,690. $278,309,156.
----------------------------------------------------------------------------------------------------------------

While NHTSA did not quantify impacts aside from the monetized
benefits from congestion and property damage savings, like the specific
quantity of solid waste avoided from reduced crashes, NHTSA believes
the benefits would increase relative to the crashes avoided and would
be relative across the different alternatives. This is based in part on
NHTSA and FMCSA's previously conducted Draft EA on heavy vehicle speed
limiting devices.\218\ While that Draft EA analyzed the effects of
reduced crash severity, there would be similar, if not increasing
benefits to avoided crashes as a result of the addition of AEB to heavy
vehicles.\219\ The PRIA discusses information related to quantified
costs and benefits of crashes, and in particular property damage due to
crashes, for each regulatory alternative in further detail.
---------------------------------------------------------------------------

\218\ Speed Limiting Devices Draft Environmental Assessment, DOT
HS 812 324 (August 2016).
\219\ Id. at 33 (``Using this procedure, the results in this
section are expected to be more conservative than if presented in
terms of crash avoidance.''
---------------------------------------------------------------------------

Cumulative Impacts
In addition to direct and indirect effects, CEQ regulations require
agencies to consider cumulative impacts of major Federal actions. CEQ
regulations define cumulative impacts as the impact ``on the
environment that result from the incremental [impact] of the action
when added to . . . other past, present, and reasonably foreseeable
future actions regardless of what agency (Federal or non-Federal) or
person undertakes such other actions.'' \220\ NHTSA notes that the
public health and safety, solid waste/property damage/congestion, air
quality and GHG emissions, socioeconomic, and hazardous material
benefits identified in this EA were based on calculations described in
the PRIA, in addition to other NHTSA actions and studies on motor
vehicle safety. That methodology required the agency to adjust
historical figures to reflect vehicle safety rulemakings that have
recently become effective. As a result, many of the calculations in
this EA already reflect the incremental impact of this action when
added to other past actions.
---------------------------------------------------------------------------

\220\ 40 CFR 1508.1(g)(3).
---------------------------------------------------------------------------

NHTSA's and other parties' past actions that improve the safety of
heavy vehicles, as well as future actions taken by the agency or other
parties that improve the safety of heavy vehicles, could further reduce
the severity or number of crashes involving these vehicles. Any such
cumulative improvement in the safety of heavy vehicles would have an
additional effect in reducing injuries and fatalities and could reduce
the quantity of solid and hazardous materials generated by crashes.
Additional federal actions like NHTSA's fuel efficiency standards for
heavy vehicles, and EPA's GHG and criteria pollutant emissions
standards for heavy vehicles, could also result in additional decreased
fuel use and emissions reductions in the future.
Agencies and Persons Consulted
This preamble describes the various materials, persons, and
agencies consulted in the development of the proposal.
Finding of No Significant Impact
Although this rule is anticipated to result in increased FMVSS
requirements for heavy vehicle manufacturers, NHTSA's analysis
indicates that it would likely result in environmental and other
socioeconomic benefits. The addition of regulatory requirements to
standardize heavy vehicle AEB is anticipated to result in no additional
fuel consumption (and accordingly, no additional GHG or criteria
pollutant emissions impacts), increasing socioeconomic and public
safety benefits depending on the regulatory alternative phase-in year
and vehicle class applicability requirements from the no-action
alternative, and an increase in benefits from the reduction in solid
waste, property damage, and congestion (including associated traffic-
level impacts like a reduction in energy consumption and tailpipe
pollutant emissions from congestion) from fewer crashes.
Based on the information in this Draft EA and assuming no
additional information or changed circumstances, NHTSA expects to issue
a Finding of No Significant Impact (FONSI).\221\ NHTSA has tentatively
concluded that none of the impacts anticipated to result from the
proposed action and alternatives under consideration will have a
significant effect on the human environment. Such a finding will be
made only after careful review of all public comments received. A Final
EA and a FONSI, if appropriate, will be issued as part of the final
rule.
---------------------------------------------------------------------------

\221\ 40 CFR 1501.6(a).

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[[Page 43233]]

FMCSA
FMCSA analyzed this rule pursuant to the National Environmental
Policy Act and determined this action is categorically excluded from
further analysis and documentation in an environmental assessment or
environmental impact statement under FMCSA Order 5610.1 (69 FR 9680,
Mar. 1, 2004), Appendix 2, paragraph 6(aa). The Categorical Exclusion
in paragraph 6(aa) covers regulations requiring motor carriers, their
officers, drivers, agents, representatives, and employees directly in
control of CMVs to inspect, repair, and provide maintenance for every
CMV used on a public road. In addition, this rule does not have any
effect on the quality of environment.

Executive Order 13132 (Federalism)

NHTSA has examined this NPRM pursuant to Executive Order 13132 (64
FR 43255, August 10, 1999) and concludes that no additional
consultation with States, local governments or their representatives is
mandated beyond the rulemaking process. The agency has concluded that
the rulemaking would not have sufficient federalism implications to
warrant consultation with State and local officials or the preparation
of a federalism summary impact statement. The NPRM would not have
``substantial direct effects on the States, on the relationship between
the national government and the States, or on the distribution of power
and responsibilities among the various levels of government.''
NHTSA rules can preempt in two ways. First, the National Traffic
and Motor Vehicle Safety Act contains an express preemption provision:
When a motor vehicle safety standard is in effect under this chapter, a
State or a political subdivision of a State may prescribe or continue
in effect a standard applicable to the same aspect of performance of a
motor vehicle or motor vehicle equipment only if the standard is
identical to the standard prescribed under this chapter. 49 U.S.C.
30103(b)(1). It is this statutory command by Congress that preempts any
non-identical State legislative and administrative law addressing the
same aspect of performance.
The express preemption provision described above is subject to a
savings clause under which ``[c]ompliance with a motor vehicle safety
standard prescribed under this chapter does not exempt a person from
liability at common law.'' 49 U.S.C. 30103(e). Pursuant to this
provision, State common law tort causes of action against motor vehicle
manufacturers that might otherwise be preempted by the express
preemption provision are generally preserved.
However, the Supreme Court has recognized the possibility, in some
instances, of implied preemption of such State common law tort causes
of action by virtue of NHTSA's rules, even if not expressly preempted.
This second way that NHTSA rules can preempt is dependent upon there
being an actual conflict between an FMVSS and the higher standard that
would effectively be imposed on motor vehicle manufacturers if someone
obtained a State common law tort judgment against the manufacturer,
notwithstanding the manufacturer's compliance with the NHTSA standard.
Because most NHTSA standards established by an FMVSS are minimum
standards, a State common law tort cause of action that seeks to impose
a higher standard on motor vehicle manufacturers will generally not be
preempted. However, if and when such a conflict does exist--for
example, when the standard at issue is both a minimum and a maximum
standard--the State common law tort cause of action is impliedly
preempted. See Geier v. American Honda Motor Co., 529 U.S. 861 (2000).
Pursuant to Executive Order 13132 and 12988, NHTSA has considered
whether this proposed rule could or should preempt State common law
causes of action. The agency's ability to announce its conclusion
regarding the preemptive effect of one of its rules reduces the
likelihood that preemption will be an issue in any subsequent tort
litigation. To this end, the agency has examined the nature (e.g., the
language and structure of the regulatory text) and objectives of this
final rule and finds that this rule, like many NHTSA rules, would
prescribe only a minimum safety standard. As such, NHTSA does not
intend this NPRM to preempt State tort law that would effectively
impose a higher standard on motor vehicle manufacturers than that
established by a final rule. Establishment of a higher standard by
means of State tort law will not conflict with the minimum standard
adopted here. Without any conflict, there could not be any implied
preemption of a State common law tort cause of action.
FMCSA has determined that this proposed rule would not have
substantial direct costs on or for States concerning the adoption and
enforcement of compatible motor carrier safety rules for intrastate
motor carriers, nor would it limit the policymaking discretion of
States. Nothing in this document would preempt any State motor carrier
safety law or regulation. Therefore, this proposed rule would not have
sufficient federalism implications to warrant the preparation of a
Federalism Impact Statement related to the delivery of FMCSA's
programs.

Civil Justice Reform

With respect to the review of the promulgation of a new regulation,
section 3(b) of Executive Order 12988, ``Civil Justice Reform'' (61 FR
4729, February 7, 1996) requires that Executive agencies make every
reasonable effort to ensure that the regulation: (1) Clearly specifies
the preemptive effect; (2) clearly specifies the effect on existing
Federal law or regulation; (3) provides a clear legal standard for
affected conduct, while promoting simplification and burden reduction;
(4) clearly specifies the retroactive effect, if any; (5) adequately
defines key terms; and (6) addresses other important issues affecting
clarity and general draftsmanship under any guidelines issued by the
Attorney General. This document is consistent with that requirement.
Pursuant to this Order, NHTSA notes as follows. The preemptive
effect of this rulemaking is discussed above. NHTSA notes further that
there is no requirement that individuals submit a petition for
reconsideration or pursue other administrative proceeding before they
may file suit in court.

Paperwork Reduction Act (PRA)

Under the PRA of 1995, a person is not required to respond to a
collection of information by a Federal agency unless the collection
displays a valid OMB control number. There are no ``collections of
information'' (as defined at 5 CFR 1320.3(c)) in this proposed rule.

National Technology Transfer and Advancement Act

Under the National Technology Transfer and Advancement Act of 1995
(NTTAA) (Public Law 104-113), all Federal agencies and departments
shall use technical standards that are developed or adopted by
voluntary consensus standards bodies, using such technical standards as
a means to carry out policy objectives or activities determined by the
agencies and departments. Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures, and business practices) that are developed or adopted by
voluntary consensus standards bodies, such as the International
Organization for Standardization (ISO) and SAE International. The NTTAA

[[Page 43234]]

directs Federal agencies to provide Congress, through OMB, explanations
when a Federal agency decides not to use available and applicable
voluntary consensus standards.
NHTSA is proposing to incorporate by reference ISO and ASTM
standards into this proposed rule. NHTSA considered several ISO
standards and has proposed to use ISO 19206-3:2021 to specify the
vehicle test device. NHTSA is incorporating by reference ASTM E1337-19,
which is already incorporated by reference into many FMVSSs, to measure
the peak braking coefficient of the testing surface.
NHTSA considered SAE J3029, Forward Collision Warning and
Mitigation Vehicle Test Procedure--Truck and Bus, which defines the
conditions for testing AEB and FCW systems. This document outlines a
basic test procedure to be performed under specified operating and
environmental conditions. It does not define tests for all possible
operating and environmental conditions. The procedures in this SAE
recommended practice are substantially similar to this proposal.
Minimum performance requirements are not addressed in SAE J3029.
In Appendix B of this preamble, NHTSA describes several
international test procedures and regulations the agency considered for
use in this NPRM. This proposed rule also has substantial technical
overlap with the UNECE No. 131 described in the appendix. First, this
proposed rule and UNECE No. 131 specify a warning and automatic
emergency braking in lead vehicle crash situations. Several lead
vehicle scenarios are nearly identical, including the stopped lead
vehicle and lead vehicle moving scenarios. Finally, NHTSA has based its
test target for the lead vehicle test device on the ``soft target
option'' condition contained in UNECE No. 152. As discussed in the
appendix, this proposed rule differs from the UNECE standards in the
areas of maximum test speed and the basic performance criteria. This
proposed rule uses higher test speeds to better match the safety
problem in the United States. This proposed rule includes a requirement
that the test vehicle avoid contact. This approach would increase the
repeatability of the test and maximize the realized safety benefits of
the rule.

Incorporation by Reference

Under regulations issued by the Office of the Federal Register (1
CFR 51.5(a)), an agency, as part of a proposed rule that includes
material incorporated by reference, must summarize material that is
proposed to be incorporated by reference and discuss the ways the
material is reasonably available to interested parties or how the
agency worked to make materials available to interested parties.
In this NPRM, NHTSA proposes to incorporate by reference three
documents into the Code of Federal Regulations, one of which is already
incorporated by reference. The document already incorporated by
reference into 49 CFR part 571 is ASTM E1337, ``Standard Test Method
for Determining Longitudinal Peak Braking Coefficient (PBC) of Paved
Surfaces Using Standard Reference Test Tire.'' ASTM E1337 is a standard
test method for evaluating peak braking coefficient of a test surface
using a standard reference test tire using a trailer towed by a
vehicle. NHTSA uses this method in all of its braking and electronic
stability control standards to evaluate the test surfaces for
conducting compliance test procedures.
NHTSA is also proposing to incorporate by reference into part 571
SAE J2400, ``Human Factors in Forward Collision Warning System:
Operating Characteristics and User Interface Requirements.'' SAE J2400
is an information report that is intended as a starting point of
reference for designers of forward collision warning systems. NHTSA
would incorporate this document by reference solely to specify the
location specification and symbol for a visual forward collision
warning.
NHTSA is proposing to incorporate by reference ISO 19206-3:2021(E),
``Test devices for target vehicles, vulnerable road users and other
objects, for assessment of active safety functions --Part 3:
Requirements for passenger vehicle 3D targets.'' This document provides
specification of three-dimensional test devices that resemble real
vehicles. It is designed to ensure the safety of the test operators and
to prevent damage to subject vehicles in the event of a collision
during testing. NHTSA is referencing many, but not all, of the
specifications of ISO 19206-3:2021(E), as discussed in section VIII.B
of this NPRM.
All standards proposed to be incorporated by reference in this NPRM
are available for review at NHTSA's headquarters in Washington, DC, and
for purchase from the organizations promulgating the standards. The
ASTM standard presently incorporated by reference into other NHTSA
regulations is also available for review at ASTM's online reading
room.\222\
---------------------------------------------------------------------------

\222\ https://www.astm/org/READINGLIBRARY/.
---------------------------------------------------------------------------

Unfunded Mandates Reform Act

The Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) requires
agencies to prepare a written assessment of the costs, benefits, and
other effects of proposed or final rules that include a Federal mandate
likely to result in the expenditures by States, local or tribal
governments, in the aggregate, or by the private sector, $100 million
or more (adjusted annually for inflation with base year of 1995) in any
one year. Adjusting this amount by the Consumer Price Index for All-
Urban Consumers (CPI-U) for the year 2021 and 1995 results in an
estimated current value of $178 million (= 2021 index value of 270.970/
1995 index value of 152.400). This proposed rule is not likely to
result in expenditures by State, local, or tribal governments of more
than $178 million in any one year. However, it is estimated to result
in the expenditures by motor vehicle manufacturers of more than $178
million. The prior section of this NPRM contains a summary of the costs
and benefits of this proposed rule, and the PRIA discusses the costs
and benefits of this proposed rule in detail.

Executive Order 13609 (Promoting International Regulatory Cooperation)

The policy statement in section 1 of E.O. 13609 states, in part,
that the regulatory approaches taken by foreign governments may differ
from those taken by U.S. regulatory agencies to address similar issues
and that, in some cases, the differences between the regulatory
approaches of U.S. agencies and those of their foreign counterparts
might not be necessary and might impair the ability of American
businesses to export and compete internationally. The E.O. states that,
in meeting shared challenges involving health, safety, labor, security,
environmental, and other issues, international regulatory cooperation
can identify approaches that are at least as protective as those that
are or would be adopted in the absence of such cooperation and that
international regulatory cooperation can also reduce, eliminate, or
prevent unnecessary differences in regulatory requirements. NHTSA
requests public comment on the ``regulatory approaches taken by foreign
governments'' concerning the subject matter of this rulemaking.

Regulation Identifier Number

The Department of Transportation assigns a regulation identifier
number (RIN) to each regulatory action listed in the Unified Agenda of
Federal Regulations. The Regulatory Information Service Center
publishes the Unified

[[Page 43235]]

Agenda in April and October of each year. You may use the RINs
contained in the heading at the beginning of this document to find this
action in the Unified Agenda.

Plain Language

Executive Order 12866 requires each agency to write all rules in
plain language. Application of the principles of plain language
includes consideration of the following questions:
Have we organized the material to suit the public's needs?
Are the requirements in the rule clearly stated?
Does the rule contain technical language or jargon that
isn't clear?
Would a different format (grouping and order of sections,
use of headings, paragraphing) make the rule easier to understand?
Would more (but shorter) sections be better?
Could we improve clarity by adding tables, lists, or
diagrams?
What else could we do to make the rule easier to
understand?
If you have any responses to these questions, please write to us
with your views.

XV. Public Participation

How long do I have to submit comments?

Please see the DATES section at the beginning of this document.

How do I prepare and submit comments?

Your comments must be written in English.
To ensure that your comments are correctly filed in the
Docket, please include the Docket Number shown at the beginning of this
document in your comments.
Your comments must not be more than 15 pages long. (49 CFR
553.21). NHTSA established this limit to encourage you to write your
primary comments in a concise fashion. However, you may attach
necessary additional documents to your comments. There is no limit on
the length of the attachments. FMCSA does not impose a page limit on
docket comments, but like NHTSA, it appreciates a concise statement of
the issues addressed by commenters.
If you are submitting comments electronically as a PDF
(Adobe) File, NHTSA asks that the documents be submitted using the
Optical Character Recognition (OCR) process, thus allowing NHTSA to
search and copy certain portions of your submissions. Comments may be
submitted to the docket electronically by logging onto the Docket
Management System website at https://www.regulations.gov. Follow the
online instructions for submitting comments.
You may also submit two copies of your comments, including
the attachments, to Docket Management at the address given above under
ADDRESSES.
Please note that pursuant to the Data Quality Act, in order for
substantive data to be relied upon and used by the agency, it must meet
the information quality standards set forth in the OMB and DOT Data
Quality Act guidelines. Accordingly, we encourage you to consult the
guidelines in preparing your comments. OMB's guidelines may be accessed
at https://www.whitehouse.gov/omb/fedreg/reproducible.html. DOT's
guidelines may be accessed at https://www.bts.gov/programs/statistical_policy_and_research/data_quality_guidelines.

How can I be sure that my comments were received?

If you wish Docket Management to notify you upon its receipt of
your comments, enclose a self-addressed, stamped postcard in the
envelope containing your comments. Upon receiving your comments, Docket
Management will return the postcard by mail.

How do I submit confidential business information?

NHTSA
If you wish to submit any information under a claim of
confidentiality, you should submit three copies of your complete
submission, including the information you claim to be confidential
business information (CBI), to the Chief Counsel, NHTSA, at the address
given above under FOR FURTHER INFORMATION CONTACT. In addition, you
should submit two copies, from which you have deleted the claimed
confidential business information, to Docket Management at the address
given above under ADDRESSES. When you send a comment containing
information claimed to be confidential business information, you should
include a cover letter setting forth the information specified in our
confidential business information regulation. (49 CFR part 512). To
facilitate social distancing during COVID-19, NHTSA is temporarily
accepting confidential business information electronically. Please see
https://www.nhtsa.gov/coronavirus/submission-confidential-business-information for details.
FMCSA
CBI is commercial or financial information that is both customarily
and actually treated as private by its owner. Under the Freedom of
Information Act (5 U.S.C. 552), CBI is exempt from public disclosure.
If your comments responsive to the NPRM contain commercial or financial
information that is customarily treated as private, that you actually
treat as private, and that is relevant or responsive to the NPRM, it is
important that you clearly designate the submitted comments as CBI.
Please mark each page of your submission that constitutes CBI as
``PROPIN'' to indicate it contains proprietary information. FMCSA will
treat such marked submissions as confidential under the Freedom of
Information Act, and they will not be placed in the public docket of
the NPRM. Submissions containing CBI should be sent to Mr. Brian
Dahlin, Chief, Regulatory Evaluation Division, Office of Policy, FMCSA,
1200 New Jersey Avenue SE, Washington, DC 20590-0001. Any comments
FMCSA receives not specifically designated as CBI will be placed in the
public docket for this rulemaking.

Will the agency consider late comments?

NHTSA will consider all comments that Docket Management receives
before the close of business on the comment closing date indicated
above under DATES. To the extent possible, we will also consider
comments that Docket Management receives after that date. If Docket
Management receives a comment too late for us to consider in developing
the final rule, we will consider that comment as an informal suggestion
for future rulemaking action. FMCSA will consider all comments and
material received during the comment period and through the closing
date up to 11:59:59 p.m. ET.

How can I read the comments submitted by other people?

You may read the comments received by Docket Management at the
address given above under ADDRESSES. The hours of the Docket are
indicated above in the same location. You may also see the comments on
the internet. To read the comments on the internet, go to https://www.regulations.gov. Follow the online instructions for accessing the
dockets.
Please note that, even after the comment closing date, we will
continue to file relevant information in the Docket as it becomes
available. Further, some people may submit late comments.

[[Page 43236]]

Accordingly, we recommend that you periodically check the Docket for
new material.

XIV. Appendices to the Preamble

Appendix A: Description of Technologies

For the convenience of readers, this section describes various
technologies of an AEB system. An AEB system employs multiple sensor
technologies and sub-systems that work together to sense a crash
imminent scenario and, where applicable, automatically apply the
vehicle brakes to avoid or mitigate a crash. Current systems utilize
radar- and camera-based sensors. AEB has been implemented in
vehicles having electronic stability control technology, which
itself leverages antilock braking system technologies. It also
builds upon older forward collision warning-only systems.

Radar-Based Sensors

At its simplest form, radar is a time-of-flight sensor that
measures the time between when a radio wave is transmitted and its
reflection is recorded. This time-of-flight is then used to
calculate the distance to the object that caused the reflection.
More information about the reflecting object, such as speed, can be
determined by comparing the output signal to the input signal.
Typical automotive applications use a type of radar called Frequency
Modulated Continuous Wave radar. This radar system sends out a radio
pulse where the pulse frequency rises through the duration of the
pulse. This pulse is reflected off the object and the radar sensor
compares the reflected signal to the original pulse to determine the
range and relative speed.
Radar sensors are widely used in AEB application, for many
reasons. These sensors can have a wide range of applicability, with
automotive grade radars sensing ranges on the order of 1 meter (3
ft) up to over 200 meters (656 ft). Radar sensors are also
relatively unaffected by time of day, precipitation, fog, and many
other adverse weather conditions. Automotive radar systems typically
operate on millimeter wave lengths, easily reflecting off even the
smallest metallic surfaces found on vehicles. Radio waves tend to
penetrate soft materials, such as rubber and plastic, allowing these
sensors to be mounted in the front ends of vehicles behind
protective, and visually appealing, grilles and bumper fascia.
Radar-based sensors have limitations that impact their
effectiveness. Radar is a line-of-sight sensor, in that they only
operate in the direction the receiving antenna is pointed and
therefore have a limited angular view. Also, while radar is
excellent at identifying radar-reflective objects, the nature of the
radar reflection makes classification of that object difficult. In
addition, objects that do not reflect radio waves easily, such as
rubber, plastic, humans, and other soft objects, are difficult for
radar-based sensors to detect. Lastly, because forward facing radar
sensors are usually mounted inside the front end of equipped
vehicles, damage caused from front-end collisions can lead to
alignment issues and reduced effectiveness.

Camera Sensors

Cameras are passive sensors in which optical data are recorded
by digital imaging chips, which are then processed to allow for
object detection and classification. They are an important part of
most automotive AEB systems and one or more cameras are typically
mounted behind the front windshield, often high up near the rearview
mirror. This provides a good view of the road, plus the windshield
wipers provide protection from debris and grease, dirt and the like
that can cover the sensor.
Camera-based imaging systems are one of the few sensor types
that can determine both color and contrast information. This makes
them able to recognize and classify objects such as road signs,
other vehicles, and pedestrians, much in the same way the human eye
does. In addition, systems that utilize two or more cameras can see
stereoscopically, allowing the processing system to determine range
information along with detection and classification.
Like all sensor systems, camera-based sensors have their
benefits and limitations. Monocular camera systems lack depth
perception and are poor at determining range, and even stereoscopic
camera systems are not ideal for determining speed. Because cameras
rely on the visible spectrum of light, conditions that make it
difficult to see such as rain, snow, sleet, fog, and even dark unlit
areas, decrease the effectiveness of perception checks of these
systems. It is also possible for the imaging sensor to saturate when
exposed to excessive light, such as driving towards the sun. For
these reasons, camera sensors are often used in conjunction with
other sensors like radar.

Electronically Modulated Braking Systems

Automatic actuation of the vehicle brakes requires more than
just systems to sense when a collision is imminent. Regardless of
how good a sensing system is, hardware is needed to physically apply
the brakes without relying on the driver to modulate the brake
pedal. The automatic braking system leverages two foundational
braking technologies, antilock braking systems and electronic safety
control.
Antilock brakes are a foundational technology that automatically
controls the degree of wheel slip during braking to prevent wheel
lock and minimize skidding, by sensing the rate of angular rotation
of the wheels and modulating the braking force at the wheels to keep
the wheels from slipping. Modern ABS systems have wheel speed
sensors and independent brake modulation at each wheel and can
increase and decrease braking pressures as needed.
ESC builds upon the antilock brakes and increases their
capability with the addition of at least two sensors, a steering
wheel angle sensor and an inertial measurement unit. These sensors
allow the ESC controller to determine intended steering direction
(from the steering wheel angle sensor), compare it to the actual
vehicle direction, and then apply appropriate braking forces at each
wheel to induce a counter yaw when the vehicle starts to lose
lateral stability. AEB uses the hardware needed for ESC and
automatically applies the brakes to avoid certain scenarios where a
crash with a vehicle is imminent.

Forward Collision Warning

Using the sensors described above, coupled with an alert
mechanism and perception calculations, a FCW system is able to
monitor a vehicle's speed, the speed of the vehicle in front of it,
and the distance between the two vehicles. If the FCW system
determines that the distance from the driver's vehicle to the
vehicle in front of it is too short, and the closing velocity
between the two vehicles is too high, the system warns the driver of
an impending rear-end collision.
Typically, FCW systems are comprised of two components: a
sensing system, which can detect a vehicle in front of the driver's
vehicle, and a warning system, which alerts the driver to a
potential crash threat. The sensing portion of the system may
consist of forward-looking radar, camera systems, lidar or a
combination of these. Warning systems in use today provide drivers
with a visual display, such as an illuminated telltale on the
instrument panel, an auditory signal (e.g., beeping tone or chime),
and/or a haptic signal that provides tactile feedback to the driver
(e.g., rapid vibrations of the seat pan or steering wheel or a
momentary brake pulse) to alert the driver of an impending crash so
that they may manually intervene (e.g., apply the vehicle's brakes
or make an evasive steering maneuver) to avoid or mitigate the
crash.
FCW systems alone are designed to warn the driver, but do not
provide automatic braking of the vehicle (some FCW systems use
haptic brake pulses to alert the driver of a crash-imminent driving
situation, but they are not intended to effectively slow the
vehicle). Since the first introduction of FCW systems, the
technology has advanced such that it is now possible to couple those
sensors, software, and alerts with the vehicles service brake system
to provide additional functionality covering a broader portion of
the safety problem.
From a functional perspective, research suggests that active
braking systems, such as AEB, provide greater safety benefits than
warning systems, such as FCW systems. However, NHTSA has found that
current AEB systems often integrate the functionalities of FCW and
AEB into one frontal crash prevention system to deliver improved
real-world safety performance and high consumer acceptance. FCW can
now be considered a component of AEB. As such, this NPRM integrates
FCW directly into the performance requirements for AEB. This
integration would also enable the agency to assess vehicles'
compliance with the proposed FCW and AEB requirements at the same
time in a single test.

Automatic Emergency Braking

Unlike systems that only alert, AEB systems (systems that
automatically apply the brakes), are designed to actively help
drivers avoid or mitigate the severity of rear-end crashes. AEB has
been previously broken into two primary functions, crash imminent
braking and dynamic brake support. CIB systems provide automatic
braking when forward-looking sensors indicate that a crash is
imminent and the driver has not applied

[[Page 43237]]

the brakes, whereas DBS systems use the same forward-looking
sensors, but provides supplemental braking after the driver applies
the brakes when sensors determine that driver-applied braking is
insufficient to avoid an imminent rear-end crash. This NPRM does not
split the terminology of these functionalities and instead discusses
them together as ``AEB.'' In some crash situations, AEB functions
independently of the driver's use of the brake pedal (CIB), while in
other situations, the vehicle uses the driver's pedal input to
better evaluate the situation and avoid the crash (in the light
vehicle context, this is called DBS). This proposal considers each
function necessary to address the safety need and presents a
performance-based regulatory approach that can permit the detailed
application of each function to be based on the specific vehicle
application and the manufacturer's approach to meeting the standard.
In response to an FCW alert or a driver noticing an imminent
crash scenario, a driver may initiate braking to avoid a rear-end
crash. In situations where the driver's braking is insufficient to
prevent a collision, the AEB system can automatically supplement the
driver's braking action to prevent or mitigate the crash. Similar to
FCW systems, AEB systems employ forward-looking sensors such as
radar and vision-based sensors to detect vehicles in the path
directly ahead and monitor a vehicle's operating conditions such as
speed or brake application. However, AEB systems can also actively
supplement braking to assist the driver whereas FCW systems serve
only to warn the driver of a potential crash threat.
If a driver does not take any action to brake when a rear-end
crash is imminent, AEB systems utilize the same types of forward-
looking sensors to apply the vehicle's brakes automatically to slow
or stop the vehicle. The amount of braking applied varies by
manufacturer, and several systems are designed to achieve maximum
vehicle deceleration just prior to impact. This NPRM would not
directly require a particular deceleration capability but specifies
situations in which crash avoidance must be achieved. Avoidance may
be produced by a combination of warnings, vehicle deceleration, and
AEB application timing.

Appendix B: International Regulatory Requirements and Other Standards

European Union (EU)

UNECE 131: Uniform provisions concerning the approval of motor
vehicles regarding the Advanced Emergency Braking Systems (AEBS).
Europe mandated AEBS for nearly all heavy vehicles starting in
November 2013. The mandate requires warning and automatic braking on
Lead Vehicle Moving (LVM) and Stopped lead vehicle (LVS), but it
does not require Dynamic Braking Support (DBS). It also requires
Forward Collision Warning (FCW) in 2 of 3 modes (audio, visual,
haptic). This mandate was implemented into two phases. Phase 1,
which is for new types (i.e., an all-new vehicle configuration) was
mandated in November 2013, and new vehicles in November 2015. Phase
2 which covers more stringent implementations, was put in place for
the new types in November 2016 and all new heavy vehicles in
November 2018. The requirements apply to buses and trucks over 3,500
kg (7,716 lbs.). EU regulations include an electronic stability
control (ESC) requirement for all heavy-duty vehicle segments.
The United Nations Economic Commission for Europe (UNECE) is the
main entity that regulates vehicle safety in the European Union.
UNECE has developed regulations for the implementation of AEBS
(using a type approval process) in motor vehicles, as described
below (UNECE Regulation 131). Regarding AEBS test procedures, the
lead-vehicle-moving scenario in UNECE regulations has a subject
vehicle speed of 80 km/h (50 mph). For the lead-vehicle-stopped
scenario, the subject vehicle speed is also 80 km/h (50 mph).
In addition, it also has false positive test requirements for
vehicle speeds of 50 km/h (31 mph). However, these false positive
test requirements are different from the ones in NHTSA's proposal,
because NHTSA uses a steel trench plate and pass-through vehicles,
as opposed to UNECE, which only uses pass-through vehicles.
There are similarities between the performance requirements of
the UNECE regulation and proposed FMVSS No. 128 as the speeds of the
subject vehicle in the scenarios of stopped lead vehicle as well as
slow moving lead vehicle are the same. However, the UNECE regulation
does not have performance requirements for decelerating lead vehicle
scenarios, which NHTSA does have. Because NHTSA has tentatively
determined it is important to have a decelerating lead vehicle test
scenario, NHTSA decided not to completely base its requirements on
the UNECE regulation parameters.
We note that UNECE 131 is considering the implementation of
Automatic Emergency Braking-Pedestrian (PAEB) into its existing
regulation. NHTSA is not proposing PAEB for heavy vehicles in this
NPRM. NHTSA believes there are unknowns at this time about the
performance of PAEB on heavy vehicles in the U.S., as well as cost
and other technical and practicability considerations to support a
proposed implementation of PAEB for heavy vehicles. Rather than
delay this NPRM to obtain this information, we have decided to
proceed with the rulemaking as set forth in this NPRM.

Japan

In January 2017, the Japanese government, under the Ministry of
Land, Infrastructure, Transport and Tourism (MLIT) presented a
proposal for UN Regulation on AEBS for M1/N1 vehicles.\223\ As part
of the harmonization efforts under consideration by the UNECE
working group (WP.29), MLIT proposed a new United Nations regulation
on AEBS in September 2008, initially including M2, N2, M3 and N3
vehicles, and having as a future target M1 and N1 vehicles. NHTSA's
consideration of UNECE Regulation 131 is discussed above.
---------------------------------------------------------------------------

\223\ https://unece.org/DAM/trans/doc/2017/wp29grrf/GRRF-83-17e.pdf.
---------------------------------------------------------------------------

South Korea

The Republic of Korea (ROK), under the Ministry of Land,
Infrastructure and Transport (MOLIT), in January 2019 required all
passenger vehicles to have AEBS and lane departure warning systems.
Those requirements were applied to trucks and other vehicles in July
2021. Article 90-3 (Advanced Emergency Braking System (AEBS)) from
the Korean standard applies to buses and trucks/special purpose
vehicle with a gross vehicle weight more than 3.5 tons (over 3,500
kg) (7,716 lbs.).\224\ The majority of the performance requirements
from the Korean standard is derived from UNECE Regulation 131.
NHTSA's consideration of ECE Regulation 131 is discussed above.
---------------------------------------------------------------------------

\224\ Regulations for Performance sand Safety Standards of Motor
Vehicle and Vehicle Parts: Article 90-3 and Table 7-8.
---------------------------------------------------------------------------

SAE International (SAE)

SAE J3029: Forward Collision Warning and Mitigation Vehicle Test
Procedure--Truck and Bus.
This SAE Recommended Practice (RP) establishes uniform powered
vehicle level test procedures for Forward Collision Avoidance and
Mitigation (FCAM) systems (also identified as AEB systems) used in
highway commercial vehicles and coaches greater than 4,535 kg
(10,000 lbs.) GVWR. This document outlines a basic test procedure to
be performed under specified operating and environmental conditions.
It does not define tests for all possible operating and
environmental conditions. Minimum performance requirements are not
addressed in this document.
When comparing the SAE test procedure with proposed FMVSS No.
128, the SAE procedure specifies lower test conditions than NHTSA's
proposal. The SAE subject vehicle speed for the stopped lead vehicle
scenario is 40.2 km/h (25 mph), compared to 80 km/h (50 mph) in this
NPRM. For the case of false activation test parameters, SAE uses
50.7 km/h (32 mph), compared to 80 km/h (50 mph) used in the NHTSA
proposed performance requirements. NHTSA is not proposing to use the
performance requirements from the SAE tests because the agency
believes they are not stringent enough to provide the level of
safety benefit the agency seeks for this NPRM.

International Organization for Standardization (ISO)

ISO 19377: Heavy commercial vehicles and buses--Emergency
braking on a defined path--Test method for trajectory measurement.
This standard describes test methods for determining the
deviation of the path travelled by a vehicle during a braking
maneuver induced by an emergency braking system from a pre-defined
desired path. The standard evaluates the vehicle path during and
following the system intervention. The corrective steering actions
for keeping the vehicle on the desired path can be applied either by
the driver or by a steering machine or by a driver assistance
system.
This document applies to heavy vehicles equipped with an
advanced emergency

[[Page 43238]]

braking system, including commercial vehicles, commercial vehicle
combinations, buses and articulated buses as defined in ISO 3833
\225\ (trucks and trailers with maximum weight above 3,5 tonnes
(3,500 kg or 7,716 lbs.) and buses and articulated buses with
maximum weight above 5 tonnes (5,000 kg or 11,023 lbs.), according
to ECE and European Commission on vehicle classification, categories
M3, N2, N3, O3 and O4).
---------------------------------------------------------------------------

\225\ ISO 3833, ``Road vehicles--Types--Terms and Definitions,''
ISO 3833 defines terms relating to some types of road vehicles
designated according to certain design and technical
characteristics. ISO 3833--European Standards (en-standard.eu).
---------------------------------------------------------------------------

NHTSA considered the ISO test procedure but decided it is
limited because the ISO standard tests braking on a defined path on
a straight line as well as braking in a constant radius curve, which
NHTSA does not. Therefore, NHTSA is not proposing performance
requirements based on the ISO standard.

Proposed Regulatory Text

List of Subjects

49 CFR Part 393

Highways and roads, Motor carriers, Motor vehicle equipment, Motor
vehicle safety.

49 CFR Part 396

Highway safety, Motor carriers, Motor vehicle safety, Reporting and
recordkeeping requirements.

49 CFR Part 571

Imports, Incorporation by reference, Motor vehicle safety,
Reporting and recordkeeping requirements, Tires.

49 CFR Part 596

Motor vehicle safety, Automatic emergency braking, Incorporation by
reference, Motor vehicle safety, Test devices.

In consideration of the foregoing, FMCSA proposes to amend 49 CFR
parts 393 and 396, and NHTSA proposes to amend part 571 and add part
596 as follows:

PART 393--PARTS AND ACCESSORIES NECESSARY FOR SAFE OPERATION

0
1. The authority citation for 49 CFR part 393 is amended to read as
follows:

Authority: 49 U.S.C. 31136, 31151, and 31502; sec. 1041(b) of
Pub. L. 102-240, 105 Stat. 1914, 1993 (1991); sec. 5301 and 5524 of
Pub. L. 114-94, 129 Stat. 1312, 1543, 1560; sec. 23010, Pub. L. 117-
58, 135 Stat. 429, 766-767, and 49 CFR 1.87.

0
2. Amend Sec. 393.5 by adding, in alphabetical order, the definition
for ``Automatic emergency braking (AEB) system'' and ``Electronic
stability control system or ESC system'' to read as follows:

Sec. 393.5 Definitions.

* * * * *
Automatic emergency braking (AEB) system is a system that detects
an imminent collision with vehicles, objects, and road users in or near
the path of a vehicle and automatically controls the vehicle's service
brakes to avoid or mitigate the collision.
Electronic stability control system or ESC system means a system
that has all of the following attributes:
(1) It augments vehicle directional stability by having the means
to apply and adjust the vehicle brake torques individually at each
wheel position on at least one front and at least one rear axle of the
vehicle to induce correcting yaw moment to limit vehicle oversteer and
to limit vehicle understeer;
(2) It enhances rollover stability by having the means to apply and
adjust the vehicle brake torques individually at each wheel position on
at least one front and at least one rear axle of the vehicle to reduce
lateral acceleration of a vehicle;
(3) It is computer-controlled with the computer using a closed-loop
algorithm to induce correcting yaw moment and enhance rollover
stability;
(4) It has a means to determine the vehicle's lateral acceleration;
(5) It has a means to determine the vehicle's yaw rate and to
estimate its side slip or side slip derivative with respect to time;
(6) It has a means to estimate vehicle mass or, if applicable,
combination vehicle mass;
(7) It has a means to monitor driver steering inputs;
(8) It has a means to modify engine torque, as necessary, to assist
the driver in maintaining control of the vehicle and/or combination
vehicle; and
(9) When installed on a truck tractor, it has the means to provide
brake pressure to automatically apply and modulate the brake torques of
a towed trailer.
* * * * *
0
3. Add Sec. 393.56 to read as follows:

Sec. 393.56 Electronic Stability Control Systems.

(a) Truck tractors manufactured between August 1, 2019 and [the
first September 1 that is 5 years after the date of publication of a
final rule]. Each truck tractor (except as provided by 49 CFR 571.136,
paragraph S3.1 or truck tractors engaged in driveaway-towaway
operations) with a gross vehicle weight rating of greater than 11,793
kilograms (26,000 pounds) manufactured on or after August 1, 2019, but
before [the first September 1 that is 5 years after the date of
publication of a final rule], must be equipped with an electronic
stability control (ESC) system that meets the requirements of Federal
Motor Vehicle Safety Standard No. 136 (49 CFR 571.136).
(b) Buses manufactured between August 1, 2019 and [the first
September 1 that is 5 years after the date of publication of a final
rule]. Each bus (except as provided by 49 CFR 571.136, paragraph S3.1
or buses engaged in driveaway-towaway operations) with a gross vehicle
weight rating of greater than 11,793 kilograms (26,000 pounds)
manufactured on or after August 1, 2019, but before [the first
September 1 that is 5 years after the date of publication of a final
rule], must be equipped with an ESC system that meets the requirements
of FMVSS No. 136.
(c) Commercial motor vehicles manufactured on and after [the first
September 1 that is 5 years after the date of publication of a final
rule]. Trucks and buses, with a GVWR greater than 4,536 kilograms
(10,000 pounds) and truck tractors manufactured on or after [the first
September 1 that is 5 years after the date of publication of a final
rule] (except trucks, buses, and truck tractors engaged in driveaway-
towaway operations), must be equipped with an electronic stability
control (ESC) system that meets the requirements of Federal Motor
Vehicle Safety Standard No. 136 (49 CFR 571.136).
(d) ESC Malfunction Detection. Each truck, truck tractor and bus
must be equipped with an indicator lamp, mounted in front of and in
clear view of the driver, which is activated whenever there is a
malfunction that affects the generation or transmission of control or
response signals in the vehicle's electronic stability control system.
0
4. Add Sec. 393.57 to read as follows:

Sec. 393.57 Automatic Emergency Braking Systems.

(a) Truck tractors manufactured on or after [the first September 1
that is 3 years after the date of publication of a final rule]. Each
truck tractor (except as provided by 49 CFR 571.136, paragraph S3.1 or
truck tractors engaged in driveaway-towaway operations) with a gross
vehicle weight rating of greater than 11,793 kilograms (26,000 pounds)
manufactured on or after the first September 1 that is 3 years after
the date of publication of a final rule], must be equipped with an
automatic emergency brake (AEB) system that meets the requirements of
Federal Motor Vehicle Safety Standard No. 128 (49 CFR 571.128).

[[Page 43239]]

(b) Buses manufactured on or after [the first September 1 that is 3
years after the date of publication of a final rule]. Each bus (except
as provided by 49 CFR 571.136, paragraph S3.1 or buses engaged in
driveaway-towaway operations) with a gross vehicle weight rating of
greater than 11,793 kilograms (26,000 pounds) manufactured on or after
the first September 1 that is 3 years after the date of publication of
a final rule], must be equipped with an AEB system that meets the
requirements of FMVSS No. 128.
(c) Commercial motor vehicles manufactured on and after [the first
September 1 that is 5 years after the date of publication of a final
rule]. Trucks and buses, with a GVWR greater than 4,536 kilograms
(10,000 pounds) and truck tractors manufactured on or after [the first
September 1 that is 5 years after the date of publication of a final
rule] (except trucks, buses, and truck tractors engaged in driveaway-
towaway), must be equipped with an AEB system that meets the
requirements of Federal Motor Vehicle Safety Standard No. 128 (49 CFR
571.128).
(d) AEB Malfunction Detection. Each commercial motor vehicle
subject to FMVSS No. 128 must be equipped with a telltale that meets
the requirements of S5.3 of FMVSS No. 128 (49 CFR 571.128), mounted in
front of and in clear view of the driver, which is activated whenever
there is a malfunction that affects the generation or transmission of
control or response signals in the vehicle's AEB system.

PART 396--INSPECTION, REPAIR, AND MAINTENANCE

0
5. The authority citation for 49 CFR part 396 is amended to read as
follows:

Authority: 49 U.S.C. 504, 31133, 31136, 31151, 31502; sec.
32934, Pub. L. 112-141, 126 Stat. 405, 830; sec. 5524, Pub. L. 114-
94, 129 Stat. 1312, 1560; sec. 23010, Pub. L. 117-58, 135 Stat. 429,
766-767 and 49 CFR 1.87.

0
6. Amend Appendix A to Part 396 by adding paragraphs 1.n. and o to read
as follows:

Appendix A to Part 396--Minimum Periodic Inspection Standards

* * * * *
1. Brake System

n. Electronic Stability Control (ESC) System.
(1) Missing ESC malfunction detection components.
(2) The ESC malfunction telltale must be identified by the
symbol shown for ``Electronic Stability Control System Malfunction''
or the specified words or abbreviations listed in Table 1 of
Standard No. 101 (Sec. 571.101).
(3) The ESC malfunction telltale must be activated as a check-
of-lamp function either when the ignition locking system is turned
to the ``On'' (``Run'') position when the engine is not running, or
when the ignition locking system is in a position between the ``On''
(``Run'') and ``Start'' that is designated by the manufacturer as a
check-light position.
(4) Other missing or inoperative ESC system components.
o. Automatic Emergency Braking (AEB).
(1) Missing AEB malfunction telltale components (e.g., bulb/LED,
wiring, etc.).
(2) AEB malfunction telltale that does not illuminate while
power is continuously applied during initial powerup.
(3) AEB malfunction telltale that stays illuminated while power
is continuously applied during normal vehicle operation.
(4) Other missing or inoperative AEB components.
* * * * *

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

0
7. The authority citation for part 571 continues to read as follows:

Authority: 49 U.S.C. 322, 30111, 30115, 30117 and 30166;
delegation of authority at 49 CFR 1.95.

0
7. Amend Sec. 571.5 by:
0
a. Revising paragraph (d)(34);
0
b. Redesignating paragraphs (l)(49) and (50) as paragraphs (l)(50) and
(51), respectively; and
0
c. Adding new paragraph (l)(49).
The revision and addition read as follows:

Sec. 571.5 Matter incorporated by reference

* * * * *
(d) * * *
(34) ASTM E1337-19, ``Standard Test Method for Determining
Longitudinal Peak Braking Coefficient (PBC) of Paved Surfaces Using
Standard Reference Test Tire,'' approved December 1, 2019, into
Sec. Sec. 571.105; 571.121; 571.122; 571.126; 571.128; 571.135;
571.136; 571.500.
* * * * *
(l) * * *
(49) SAE J2400, ``Human Factors in Forward Collision Warning
System: Operating Characteristics and User Interface Requirements,''
August 2003 into Sec. 571.128.
* * * * *
0
9. Add Sec. 571.128 to read as follows:

Sec. 571.128 Standard No. 128; Automatic emergency braking systems
for heavy vehicles.

S1. Scope. This standard establishes performance requirements for
automatic emergency braking (AEB) systems for heavy vehicles.
S2. Purpose. The purpose of this standard is to reduce the number
of deaths and injuries that result from crashes in which drivers do not
apply the brakes or fail to apply sufficient braking power to avoid or
mitigate a crash.
S3. Application. This standard applies to multipurpose passenger
vehicles, trucks, and buses with a gross vehicle weight rating greater
than 4,536 kilograms (10,000 pounds) that are subject to Sec. Sec.
571.105 or 571.121 of this part.
S4. Definitions.
Adaptive cruise control system is an automatic speed control system
that allows the equipped vehicle to follow a lead vehicle at a pre-
selected gap by controlling the engine, power train, and service
brakes.
Ambient illumination is the illumination as measured at the test
surface, not including any illumination provided by the subject
vehicle.
Automatic emergency braking (AEB) system is a system that detects
an imminent collision with vehicles, objects, and road users in or near
the path of a vehicle and automatically controls the vehicle's service
brakes to avoid or mitigate the collision.
Brake pedal application onset is when the brake controller begins
to displace the brake pedal.
Forward collision warning is an auditory and visual warning
provided to the vehicle operator by the AEB system that is designed to
induce an immediate forward crash avoidance response by the vehicle
operator.
Forward collision warning onset is the first moment in time when a
forward collision warning is provided.
Headway is the distance between the lead vehicle's rearmost plane
normal to its centerline and the subject vehicle's frontmost plane
normal to its centerline.
Lead vehicle is a vehicle test device facing the same direction and
preceding a subject vehicle within the same travel lane.
Lead vehicle braking onset is the point at which the lead vehicle
achieves a deceleration of 0.05g due to brake application.
Over-the-road bus means a bus characterized by an elevated
passenger deck located over a baggage compartment, except a school bus.
Perimeter-seating bus means a bus with 7 or fewer designated
seating positions rearward of the driver's seating position that are
forward-facing or can convert to forward-facing without the use of
tools and is not an over-the-road bus.
Small-volume manufacturer means an original vehicle manufacturer
that produces or assembles fewer than 5,000 vehicles annually for sales
in the United States.

[[Page 43240]]

Steel trench plate is a rectangular steel plate often used in road
construction to temporarily cover sections of pavement unsafe to drive
over directly.
Subject vehicle is the vehicle under examination for compliance
with this standard.
Transit bus means a bus that is equipped with a stop-request system
sold for public transportation provided by, or on behalf of, a State or
local government and that is not an over-the-road bus.
Travel path is the path projected onto the road surface of a point
located at the intersection of the subject vehicle's frontmost vertical
plane and longitudinal vertical center plane, as the subject vehicle
travels forward.
Vehicle test device is a device meeting the specifications set
forth in subpart C of 49 CFR part 596.
S5. Requirements.
(a) Truck tractors and buses with a GVWR greater than 11,793
kilograms (26,000 pounds), other than school buses, perimeter-seating
buses, and transit buses and which are manufactured on or after [the
first September 1 that is three years after the date of publication of
a final rule] must meet the requirements of this standard.
(b) Vehicles with a GVWR greater than 4,536 kilograms (10,000
pounds) which are manufactured on or after [the first September 1 that
is four years after the date of publication of a final rule] must meet
the requirements of this standard.
(c) The requirements of paragraphs (a) and (b) of this section S5
do not apply to small-volume manufacturers, final-stage manufacturers
and alterers until one year after the dates specified in those
paragraphs.
S5.1. Requirements when approaching a lead vehicle.
S5.1.1. Forward Collision Warning. A vehicle is required to have a
forward collision warning system, as defined in S4 of this section,
that provides an auditory and visual signal to the driver of an
impending collision with a lead vehicle when traveling at any forward
speed greater than 10 km/h (6.2 mph). The auditory signal must have a
high fundamental frequency of at least 800 Hz, a duty cycle of 0.25--
0.95, and tempo in the range of 6-12 pulses per second. The visual
signal must be located according to SAE J2400 (incorporated by
reference, see Sec. 571.5), paragraph 4.1.14, and must include the
symbol in the bottom right of paragraph 4.1.16. Line of sight is based
on the forward-looking eye midpoint (Mf) as described in
S14.1.5 of Sec. 571.111. The symbol must be red in color and steady-
burning.
S5.1.2. Automatic Emergency Braking. A vehicle is required to have
an automatic emergency braking system, as defined in S4 of this
section, that applies the service brakes automatically when a collision
with a lead vehicle is imminent. The system must operate when the
vehicle is traveling at any forward speed greater than 10 km/h (6.2
mph).
S5.1.3. Performance Test Requirements. The vehicle must provide a
forward collision warning and subsequently apply the service brakes
automatically when a collision with a lead vehicle is imminent such
that the subject vehicle does not collide with the lead vehicle when
tested using the procedures in S7. The forward collision warning is not
required if adaptive cruise control is engaged.
S5.2. False Activation. The vehicle must not automatically apply
braking that results in peak deceleration of 0.25g or greater when
manual braking is not applied, nor a peak deceleration of 0.45g or
greater when manual braking is applied, when tested using the
procedures in S8.
S5.3. Malfunction Detection. The system must continuously detect
system malfunctions, including malfunctions caused solely by sensor
obstructions. If the system detects a malfunction that prevents the
system from meeting the requirements specified in S5.1 or S5.2, the
system must provide the vehicle operator with a telltale that the
malfunction exists.
S6. Test Conditions.
S6.1. Environmental conditions.
S6.1.1. Temperature. The ambient temperature is any temperature
between 2 [deg]C and 40 [deg]C.
S6.1.2. Wind. The maximum wind speed is no greater than 5 m/s (11
mph) during tests approaching a lead vehicle.
S6.1.3. Ambient Lighting.
(a) The ambient illumination on the test surface is any level at or
above 2,000 lux.
(b) Testing is not performed while driving toward or away from the
sun such that the horizontal angle between the sun and a vertical plane
containing the centerline of the subject vehicle is less than 25
degrees and the solar elevation angle is less than 15 degrees.
S6.1.4. Precipitation. Testing is not conducted during periods of
precipitation or when visibility is affected by fog, smoke, ash, or
other particulate.
S6.2. Road conditions.
S6.2.1. Test Track Surface and Construction. The tests are
conducted on a dry, uniform, solid-paved surface. Surfaces with debris,
irregularities, or undulations, such as loose pavement, large cracks,
or dips are not used.
S6.2.2. Surface Friction. The road test surface produces a peak
friction coefficient (PFC) of 1.02 when measured using an ASTM
International (ASTM) F2493 standard reference test tire, in accordance
with ASTM E1337-19 (incorporated by reference, see Sec. 571.5), at a
speed of 64 km/h (40 mph), without water delivery.
S6.2.3. Slope. The test surface has any consistent slope between 0
percent and 1 percent.
S6.2.4. Markings. The road surface within 2.3 m of the intended
travel path is marked with zero, one, or two lines of any configuration
or color. If one line is used, it is straight. If two lines are used,
they are straight, parallel to each other, and at any distance from 2.7
m to 4.5 m apart.
S6.2.5. Obstructions. Testing is conducted such that the vehicle
does not travel beneath any overhead structures, including but not
limited to overhead signs, bridges, or gantries. No vehicles,
obstructions, or stationary objects are within 7.4 m of either side of
the intended travel path except as specified.
S6.3. Subject vehicle conditions.
S6.3.1. Malfunction notification. Testing is not conducted while
the AEB malfunction telltale specified in S5.3 is illuminated.
S6.3.2. Sensor obstruction. All sensors used by the system and any
part of the vehicle immediately ahead of the sensors, such as plastic
trim, the windshield, etc., are free of debris or obstructions.
S6.3.3. Tires. The vehicle is equipped with the original tires
present at the time of initial sale. The tires are inflated to the
vehicle manufacturer's recommended cold tire inflation pressure(s)
specified on the vehicle's placard or the tire inflation pressure
label.
S6.3.4. Brake burnish.
(a) Vehicles subject to Sec. 571.105 are burnished in accordance
with S7.4 of that section.
(b) Vehicles subject to Sec. 571.121 are burnished in accordance
with S6.1.8 of that section.
S6.3.5. Brake temperature. The average temperature of the service
brakes on the hottest axle of the vehicle during testing, measured
according to S6.1.16 of Sec. 571.121, is between 66[deg]C and
204[deg]C prior to braking.
S6.3.6. Fluids. All non-consumable fluids for the vehicle are at
100 percent capacity. All consumable fluids are at any level from 5 to
100 percent capacity.

[[Page 43241]]

S6.3.7. Propulsion battery charge. The propulsion batteries are
charged at any level from 5 to 100 percent capacity.
S6.3.8. Cruise control. Cruise control, including adaptive cruise
control, is configured under any available setting.
S6.3.9. Adjustable forward collision warning. Forward collision
warning is configured in any operator-configurable setting.
S6.3.10. Engine braking. A vehicle equipped with an engine braking
system that is engaged and disengaged by the operator is tested with
the system in any selectable configuration.
S6.3.11. Regenerative braking. Regenerative braking is configured
under any available setting.
S6.3.12. Liftable Axles. A vehicle with one or more liftable axles
is tested with the liftable axles down.
S6.3.13. Headlamps. Testing is conducted with the headlamp control
in any selectable position.
S6.3.14. Subject vehicle loading.
(a) Except as provided in S6.3.14(b), the vehicle is loaded to its
GVWR so that the load on each axle, measured at the tire-ground
interface, is most nearly proportional to the axles' respective GAWRs,
without exceeding the GAWR of any axle.
(b) Truck tractors.
(1) A truck tractor is loaded to its GVWR with the operator and
test instrumentation, and by coupling it to a control trailer as
provided in S6.3.14(b)(2) of this section and placing ballast (weight)
on the control trailer which loads the tractor's non-steer axles. The
control trailer is loaded with ballast without exceeding the GAWR of
the trailer axle. The location of the center of gravity of the ballast
on the control trailer is directly above the kingpin. The height of the
center of gravity of the ballast on the control trailer is less than
610 mm (24 inches) above the top of the tractor's fifth-wheel hitch
(the area where the truck tractor attaches to the trailer). If the
tractor's fifth-wheel hitch position is adjustable, the fifth-wheel
hitch is adjusted to proportionally distribute the load on each of the
tractor's axle(s), according to each axle's GAWR, without exceeding the
GAWR of any axle(s). If the fifth-wheel hitch position cannot be
adjusted to prevent the load from exceeding the GAWR of the tractor's
axle(s), the ballast is reduced until the axle load is equal to or less
than the GAWR of the tractor's rear axle(s), maintaining load
proportioning as close as possible to specified proportioning.
(2) The control trailer is an unbraked, flatbed semi-trailer that
has a single axle with a GAWR of 8,165 kilograms (18,000 pounds). The
control trailer has a length of at least 6,400 mm (252 inches), but no
more than 7,010 mm (276 inches), when measured from the transverse
centerline of the axle to the centerline of the kingpin (the point
where the trailer attaches to the truck tractor). At the manufacturer's
option, truck tractors with four or more axles may use a control
trailer with a length of more than 7,010 mm (276 inches), but no more
than 13,208 mm (520 inches) when measured from the transverse
centerline of the axle to the centerline of the kingpin.
S6.3.15. AEB system initialization. The vehicle is driven at a
speed of 10 km/h or higher for at least one minute prior to testing,
and subsequently the starting system is not cycled off prior to
testing.
S6.4. Equipment and test Devices.
S6.4.1. The vehicle test device is specified in 49 CFR part 596
subpart C. Local fluttering of the lead vehicle's external surfaces
does not exceed 10 mm perpendicularly from the reference surface, and
distortion of the lead vehicle's overall shape does not exceed 25 mm in
any direction.
S6.4.2. The steel trench plate used for the false activation test
has the dimensions 2.4 m x 3.7 m x 25 mm and is made of ASTM A36 steel.
Any metallic fasteners used to secure the steel trench plate are flush
with the top surface of the steel trench plate.
S7. Testing when approaching a lead vehicle.
S7.1. Setup.
(a) The testing area is set up in accordance with Figure 1 to this
section.
(b) Testing is conducted during daylight.
(c) For reference, Table 1 to S7.1 specifies the subject vehicle
speed (VSV), lead vehicle speed (VLV), headway,
and lead vehicle deceleration for each test that may be conducted.
(d) The intended travel path of the vehicle is a straight line
toward the lead vehicle from the location corresponding to a headway of
L0.
(e) If the road surface is marked with a single or double lane
line, the intended travel path is parallel to and 1.8 m from the inside
of the closest line. If the road surface is marked with two lane lines
bordering the lane, the intended travel path is centered between the
two lines.
(f) For each test run conducted, the subject vehicle speed
(VSV), lead vehicle speed (VLV), headway, and
lead vehicle deceleration will be selected from the ranges specified.

Table 1 to S7.1--Test Parameters When Approaching a Lead Vehicle
--------------------------------------------------------------------------------------------------------------------------------------------------------
Speed (km/h)
Test scenarios ----------------------------------------- Headway (m) Lead vehicle decel (g) Manual brake
VSV VLV application
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stopped Lead Vehicle................ Any 10-80.............. 0 ....................... ....................... no.
Any 70-100............. 0 ....................... ....................... yes.
Slower-Moving Lead Vehicle.......... Any 40-80.............. 20 ....................... ....................... no.
Any 70-100............. 20 ....................... ....................... yes.
Decelerating Lead Vehicle........... 50..................... 50 Any 21-40.............. Any 0.3-0.4............ no.
50..................... 50 Any 21-40.............. Any 0.3-0.4............ yes.
80..................... 80 Any 28-40.............. Any 0.3-0.4............ no.
80..................... 80 Any 28-40.............. Any 0.3-0.4............ yes.
--------------------------------------------------------------------------------------------------------------------------------------------------------

S7.2. Headway calculation. For each test run conducted under S7.3
and S7.4, the headway (L0), in meters, providing 5 seconds time to
collision (TTC) is calculated. L0 is determined with the following
equation where VSV is the speed of the subject vehicle in m/s and VLV
is the speed of the lead vehicle in m/s:

L0 = TTC0 x (VSV-VLV)
TTC0 = 5

S7.3. Stopped lead vehicle.
S7.3.1. Test parameters.
(a) For testing with no subject vehicle manual brake application,
the subject vehicle test speed is any speed between 10 km/h and 80 km/
h, and the lead vehicle speed is 0 km/h.
(b) For testing with manual brake application of the subject
vehicle, the

[[Page 43242]]

subject vehicle test speed is any speed between 70 km/h and 100 km/h,
and the lead vehicle speed is 0 km/h.
S7.3.2. Test conduct prior to forward collision warning onset.
(a) The lead vehicle is placed stationary with its longitudinal
centerline coincident to the intended travel path.
(b) Before the headway corresponds to L0, the subject
vehicle is driven at any speed, in any direction, on any road surface,
for any amount of time.
(c) The subject vehicle approaches the rear of the lead vehicle.
(d) Beginning when the headway corresponds to L0, the
subject vehicle speed is maintained within 1.6 km/h of the test speed
with minimal and smooth accelerator pedal inputs.
(e) Beginning when the headway corresponds to L0, the
subject vehicle heading is maintained with minimal steering input such
that the travel path does not deviate more than 0.3 m laterally from
the intended travel path and the subject vehicle's yaw rate does not
exceed 1.0 deg/s.
S7.3.3. Test conduct after forward collision warning onset.
(a) The accelerator pedal is released at any rate such that it is
fully released within 500 ms. This action is omitted for vehicles
tested with cruise control active.
(b) For testing conducted with manual brake application, the
service brakes are applied as specified in S9. The onset of brake pedal
application occurs 1.0 0.1 second after forward collision
warning onset.
(c) For testing conducted without manual brake application, no
manual brake application is made until the test completion criteria of
S7.3.4 are satisfied.
S7.3.4. Test completion criteria. The test run is complete when the
subject vehicle comes to a complete stop without making contact with
the lead vehicle or when the subject vehicle makes contact with the
lead vehicle.
S7.4. Slower-moving lead vehicle.
S7.4.1. Test parameters.
(a) For testing with no subject vehicle manual brake application,
the subject vehicle test speed is any speed between 40 km/h and 80 km/
h, and the lead vehicle speed is 20 km/h.
(b) For testing with manual brake application of the subject
vehicle, the subject vehicle test speed is any speed between 70 km/h
and 100 km/h, and the lead vehicle speed is 20 km/h.
S7.4.2. Test conduct prior to forward collision warning onset.
(a) The lead vehicle is propelled forward in a manner such that the
longitudinal center plane of the lead vehicle does not deviate
laterally more than 0.3m from the intended travel path.
(b) The subject vehicle approaches the lead vehicle.
(c) Beginning when the headway corresponds to L0, the
subject vehicle and lead vehicle speed is maintained within 1.6 km/h of
the test speed with minimal and smooth accelerator pedal inputs.
(d) Beginning when the headway corresponds to L0, the
subject vehicle and lead vehicle headings are maintained with minimal
steering input such that the subject vehicle's travel path does not
deviate more than 0.3 m laterally from the centerline of the lead
vehicle, and the yaw rate of the subject vehicle does not exceed 1.0 deg/s prior to forward collision warning onset.
S7.4.3. Test conduct after forward collision warning onset.
(a) The subject vehicle's accelerator pedal is released at any rate
such that it is fully released within 500 ms. This action is omitted
for vehicles tested with cruise control active.
(b) For testing conducted with manual braking application, the
service brakes are applied as specified in S9. The onset of brake pedal
application is 1.0 0.1 second after the forward collision
warning onset.
(c) For testing conducted without manual braking application, no
manual brake application is made until the test completion criteria of
S7.4.4 are satisfied.
S7.4.4. Test completion criteria. The test run is complete when the
subject vehicle speed is less than or equal to the lead vehicle speed
without making contact with the lead vehicle or when the subject
vehicle makes contact with the lead vehicle.
S7.5. Decelerating lead vehicle.
S7.5.1. Test parameters.
(a) The subject vehicle test speed is 50 km/h or 80 km/h, and the
lead vehicle speed is identical to the subject vehicle test speed.
(b) [Reserved]
S7.5.2. Test conduct prior to lead vehicle braking onset.
(a) Before the 1 second prior to lead vehicle braking onset, the
subject vehicle is driven at any speed, in any direction, on any road
surface, for any amount of time.
(b) Between 1 second prior to lead vehicle braking onset and lead
vehicle braking onset:
(1) The lead vehicle is propelled forward in a manner such that the
longitudinal center plane of the vehicle does not deviate laterally
more than 0.3 m from the intended travel path.
(2) The subject vehicle follows the lead vehicle at a headway of
any distance between 21 m and 40 m if the subject vehicle test speed is
50 km/h, or any distance between 28 m and 40 m if the subject vehicle
test speed is 80 km/h.
(3) The subject vehicle's speed is maintained within 1.6 km/h of
the test speed with minimal and smooth accelerator pedal inputs prior
to forward collision warning onset.
(4) The lead vehicle's speed is maintained within 1.6 km/h.
(5) The subject vehicle and lead vehicle headings are maintained
with minimal steering input such that their travel paths do not deviate
more than 0.3 m laterally from the centerline of the lead vehicle, and
the yaw rate of the subject vehicle does not exceed 1.0
deg/s until forward collision warning onset.
S7.5.3. Test conduct following lead vehicle braking onset.
(a) The lead vehicle is decelerated to a stop with a targeted
average deceleration of any value between 0.3g and 0.4g. The targeted
deceleration magnitude is achieved within 1.5 seconds of lead vehicle
braking onset and is maintained until 250 ms prior to coming to a stop.
(b) After forward collision warning onset, the subject vehicle's
accelerator pedal is released at any rate such that it is fully
released within 500 ms. This action is omitted for vehicles with cruise
control active.
(c) For testing conducted with manual braking application, the
service brakes are applied as specified in S9. The brake pedal
application onset occurs 1.0 0.1 second after the forward
collision warning onset.
(d) For testing conducted without manual braking application, no
manual brake application is made until the test completion criteria of
S7.5.4 are satisfied.
S7.5.4. Test completion criteria. The test run is complete when the
subject vehicle comes to a complete stop without making contact with
the lead vehicle or when the subject vehicle makes contact with the
lead vehicle.
S8. False AEB activation.
S8.1. Headway calculation. For each test run to be conducted under
S8.2 and S8.3, the headway (L0, L2.1, L1.1), in meters, between the
front plane of the subject vehicle and either the steel trench plate's
leading edge or the rearmost plane normal to the centerline of the
vehicle test devices providing 5.0 seconds, 2.1 seconds, and 1.1
seconds time to collision (TTC) is calculated. L0, L2.1, and L1.1 are
determined with the following equation where VSV is the speed of the
subject vehicle in m/s:

Lx = TTCx x (VSV)

[[Page 43243]]

TTC0 = 5.0
TTC2.1 = 2.1
TTC1.1 = 1.1

S8.2. Steel trench plate.
S8.2.1. Test parameters and setup.
(a) The testing area is set up in accordance with Figure 2 to this
section.
(b) The steel trench plate is secured flat on the test surface so
that its longest side is parallel to the subject vehicle's intended
travel path and horizontally centered on the subject vehicle's intended
travel path.
(c) The subject vehicle test speed is 80 km/h.
S8.2.2. Test conduct.
(a) The subject vehicle approaches the steel trench plate.
(b) Beginning when the headway corresponds to L0, the
subject vehicle speed is maintained within 1.6 km/h of the test speed
with minimal and smooth accelerator pedal inputs.
(c) Beginning when the headway corresponds to L0, the
subject vehicle heading is maintained with minimal steering input such
that the travel path does not deviate more than 0.3 m laterally from
the intended travel path, and the yaw rate of the subject vehicle does
not exceed 1.0 deg/s.
(d) If forward collision warning occurs, the subject vehicle's
accelerator pedal is released at any rate such that it is fully
released within 500 ms. This action is omitted for vehicles with cruise
control active.
(e) For tests where no manual brake application occurs, manual
braking is not applied until the test completion criteria of S8.2.3 are
satisfied.
(f) For tests where manual brake application occurs, the subject
vehicle's accelerator pedal, if not already released, is released when
the headway corresponds to L2.1 at any rate such that it is
fully released within 500 ms.
(g) For tests where manual brake application occurs, the service
brakes are applied as specified in S9. The brake application pedal
onset occurs at headway L1.1.
S8.2.3. Test completion criteria. The test run is complete when the
subject vehicle comes to a stop prior to crossing over the leading edge
of the steel trench plate or when the subject vehicle crosses over the
leading edge of the steel trench plate.
S8.3. Pass-through.
S8.3.1. Test parameters and setup.
(a) The testing area is set up in accordance with Figure 3 to this
section.
(b) Two vehicle test devices are secured in a stationary position
parallel to one another with a lateral distance of 4.5 m 0.1 m between the vehicles' closest front wheels. The centerline
between the two vehicles is parallel to the intended travel path.
(c) The subject vehicle test speed is 80 km/h.
(d) Testing may be conducted with manual subject vehicle pedal
application.
S8.3.2. Test conduct.
(a) The subject vehicle approaches the gap between the two vehicle
test devices.
(b) Beginning when the headway corresponds to L0, the
subject vehicle speed is maintained within 1.6 km/h with minimal and
smooth accelerator pedal inputs.
(c) Beginning when the headway corresponds to L0, the
subject vehicle heading is maintained with minimal steering input such
that the travel path does not deviate more than 0.3 m laterally from
the intended travel path, and the yaw rate of the subject vehicle does
not exceed 1.0 deg/s.
(d) If forward collision warning occurs, the subject vehicle's
accelerator pedal is released at any rate such that it is fully
released within 500 ms.
(e) For tests where no manual brake application occurs, manual
braking is not applied until the test completion criteria of S8.3.3 are
satisfied.
(f) For tests where manual brake application occurs, the subject
vehicle's accelerator pedal, if not already released, is released when
the headway corresponds to L2.1 at any rate such that it is
fully released within 500 ms.
(g) For tests where manual brake application occurs, the service
brakes are applied as specified in S9. The brake application onset
occurs when the headway corresponds to L1.1.
S8.3.3. Test completion criteria. The test run is complete when the
subject vehicle comes to a stop prior to its rearmost point passing the
vertical plane connecting the forwardmost point of the vehicle test
devices or when the rearmost point of the subject vehicle passes the
vertical plane connecting the forwardmost point of the vehicle test
devices.
S9. Subject Vehicle Brake Application Procedure.
S9.1. The procedure begins with the subject vehicle brake pedal in
its natural resting position with no preload or position offset.
S9.2. At the option of the manufacturer, either displacement
feedback or hybrid feedback control is used.
S9.3. Displacement feedback procedure. For displacement feedback,
the commanded brake pedal position is the brake pedal position that
results in a mean deceleration of 0.3g in the absence of AEB system
activation.
(a) The mean deceleration is the deceleration over the time from
the pedal achieving the commanded position to 250 ms before the vehicle
comes to a stop.
(b) The pedal displacement controller depresses the pedal at a rate
of 254 mm/s 25.4 mm/s to the commanded brake pedal
position.
(c) The pedal displacement controller may overshoot the commanded
position by any amount up to 20 percent. If such an overshoot occurs,
it is corrected within 100 ms.
(d) The achieved brake pedal position is any position within 10
percent of the commanded position from 100 ms after pedal displacement
occurs and any overshoot is corrected.
S9.4. Hybrid brake pedal feedback procedure. For hybrid brake pedal
feedback, the commanded brake pedal application is the brake pedal
position and a subsequent commanded brake pedal force that results in a
mean deceleration of 0.3g in the absence of AEB system activation.
(a) The mean deceleration is the deceleration over the time from
the pedal achieving the commanded position to 250 ms before the vehicle
comes to a stop.
(b) The hybrid controller displaces the pedal at a rate of 254 mm/s
25.4 mm/s to the commanded pedal position.
(c) The hybrid controller may overshoot the commanded position by
any amount up to 20 percent. If such an overshoot occurs, it is
corrected within 100 ms.
(d) The hybrid controller begins to control the force applied to
the pedal and stops controlling pedal displacement 100 ms after pedal
displacement occurs and any overshoot is corrected.
(e) The hybrid controller applies a pedal force of at least 11.1 N.
(f) The applied pedal force is maintained within 10 percent of the
commanded brake pedal force from 350 ms after commended pedal
displacement occurs and any overshoot is corrected until test
completion.

[[Page 43244]]

Figure 1 to Sec. 571.128--Setup for Tests Approaching a Lead Vehicle

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[GRAPHIC] [TIFF OMITTED] TP06JY23.010

Figure 2 to Sec. 571.128--Setup for Steel Trench Plate False
Activation Tests
[GRAPHIC] [TIFF OMITTED] TP06JY23.011

Figure 3 to Sec. 571.128--Setup for Pass-Through False Activation
Tests

[[Page 43245]]

[GRAPHIC] [TIFF OMITTED] TP06JY23.012

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0
9. Amend Sec. 571.136 by revising paragraphs S3, S3.1, S3.2, and
paragraphs (1) and (2) of the definition of ``Electronic stability
control system or ESC system'' in S4, and adding S8.3 to read as
follows:

Sec. 571.136 Standard No. 136; Electronic stability control systems
for heavy vehicles.

* * * * *
S3 Application.
S3.1 This standard applies to passenger cars, multipurpose
passenger vehicles, trucks, and buses, with a GVWR greater than 4,536
kilograms (10,000 pounds) except:
(a) Any vehicle equipped with an axle that has a gross axle weight
rating of 13,154 kilograms (29,000 pounds) or more;
(b) Any truck or bus that has a speed attainable in 3.2 kilometers
(2 miles) of not more than 53 km/h (33 mph); and
(c) Any truck that has a speed attainable in 3.2 kilometers (2
miles) of not more than 72 km/h (45 mph), an unloaded vehicle weight
that is not less than 95 percent of its gross vehicle weight rating,
and no capacity to carry occupants other than the driver and operating
crew.
S3.2 The following vehicles are subject only to the requirements in
S5.1, S5.2, and S5.4 of this standard:
(a) Vehicles with a gross vehicle weight rating of 11,793 kilograms
(26,000 pounds) or less;
(b) Trucks other than truck tractors;
(c) School buses;
(d) Perimeter-seating buses;
(e) Transit buses;
(f) Passenger cars; and
(g) Multipurpose passenger vehicles.
* * * * *
S4 Definitions
* * * * *
Electronic stability control system or ESC system means a system
that has all of the following attributes:
(1) It augments vehicle directional stability by having the means
to apply and adjust the vehicle brake torques individually at each
wheel position on at least one front and at least one rear axle of the
vehicle to induce correcting yaw moment to limit vehicle oversteer and
to limit vehicle understeer;
(2) It enhances rollover stability by having the means to apply and
adjust the vehicle brake torques individually at each wheel position on
at least one front and at least one rear axle of the vehicle to reduce
lateral acceleration of a vehicle;
* * * * *
S8.3 Vehicles with a gross vehicle weight rating of 11,793
kilograms (26,000 pounds) or less, trucks other than truck tractors,
school buses, perimeter-seating buses, transit buses, passenger cars,
and multipurpose passenger vehicles are not required to comply this
standard before [the first September 1 that is four years after the
date of publication of a final rule].
* * * * *
0
11. Add part 596 to read as follows.

PART 596--AUTOMATIC EMERGENCY BRAKING TEST DEVICES

Subpart A--General

Sec.
596.1 Scope.
596.2 Purpose.
596.3 Application
596.4 Definitions.
596.5 Matter incorporated by reference.
Subpart B--[Reserved]
Subpart C--Vehicle Test Device
596.9 General Description
596.10 Specifications for the Vehicle Test Device

Authority: 49 U.S.C. 322, 30111, 30115, 30117 and 30166;
delegation of authority at 49 CFR 1.95.

Subpart A--General

Sec. 596.1 Scope.

This part describes the test devices that are to be used for
compliance testing of motor vehicles with motor vehicle safety
standards for automatic emergency braking.

Sec. 596.2 Purpose.

The design and performance criteria specified in this part are
intended to describe devices with sufficient precision such that
testing performed with these test devices will produce repetitive and
correlative results under similar test conditions to reflect adequately
the automatic emergency braking performance of a motor vehicle.

Sec. 596.3 Application.

This part does not in itself impose duties or liabilities on any
person. It is a description of tools that are used in compliance tests
to measure the performance of automatic emergency braking systems
required by the safety standards that refer to these tools. This part
is designed to be referenced by, and become part of, the test
procedures specified in motor vehicle safety standards.

Sec. 596.4 Definitions.

All terms defined in section 30102 of the National Traffic and
Motor Vehicle Safety Act (49 U.S.C. chapter 301, et seq.) are used in
their statutory meaning.
Vehicle Test Device means a test device that simulates a passenger
vehicle for the purpose of testing automatic emergency brake system
performance.
Vehicle Test Device Carrier means a movable platform on which a
Lead Vehicle Test Device may be attached during compliance testing.

[[Page 43246]]

Sec. 596.5 Matter incorporated by reference.

(a) Certain material is incorporated by reference into this part
with the approval of the Director of the Federal Register under 5
U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other than that
specified in this section, the National Highway Traffic Safety
Administration (NHTSA) must publish notice of change in the Federal
Register and the material must be available to the public. All approved
material is available for inspection at NHTSA at the National Archives
and Records Administration (NARA). Contact NHTSA at: NHTSA Office of
Technical Information Services, 1200 New Jersey Avenue SE, Washington,
DC 20590; (202) 366-2588. For information on the availability of this
material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations.html or email [email protected]. The material may be
obtained from the source(s) in the following paragraph of this section.
(b) International Organization for Standardization (ISO), 1, ch. de
la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland; phone: + 41 22
749 01 11; fax: + 41 22 733 34 30; website: www.iso.org/.
(1) [Reserved].
(2) [Reserved].
(3) ISO 19206-3:2021(E), ``Test devices for target vehicles,
vulnerable road users and other objects, for assessment of active
safety functions--Part 3: Requirements for passenger vehicle 3D
targets,'' First edition, 2021-05; into Sec. 596.10.
(4) [Reserved]

Subpart B--[Reserved]

Subpart C--Vehicle Test Device

Sec. 596.9 General Description.

(a) The Vehicle Test Device provides a sensor representation of a
passenger motor vehicle.
(b) The rear view of the Vehicle Test Device contains
representations of the vehicle silhouette, a rear window, a high-
mounted stop lamp, two taillamps, a rear license plate, two rear reflex
reflectors, and two tires.

Sec. 596.10 Specifications for the Vehicle Test Device.

(a) Word Usage--Recommendations. The words ``recommended,''
``should,'' ``can be,'' or ``should be'' appearing in sections of ISO
19206-3:2021(E) (incorporated by reference, see Sec. 596.5),
referenced in this section, are read as setting forth specifications
that are used.
(b) Word Usage--Options. The words ``may be,'' or ``either,'' used
in connection with a set of items appearing in sections of ISO 19206-
3:2021(E) (incorporated by reference, see Sec. 596.5), referenced in
this section, are read as setting forth the totality of items, any one
of which may be selected by NHTSA for testing.
(c) Dimensional specifications. (1) The rear silhouette and the
rear window are symmetrical about a shared vertical centerline.
(2) Representations of the taillamps, rear reflex reflectors, and
tires are symmetrical about the surrogate's centerline.
(3) The license plate representation has a width of 300 15 mm and a height of 150 15 mm and mounted with a
license plate holder angle within the range described in 49 CFR 571.108
S6.6.3.1.
(4) The Vehicle Test Device representations are located within the
minimum and maximum measurement values specified in columns 3 and 4 of
Tables A.4 of ISO 19206-3:2021(E) Annex A (incorporated by reference,
see Sec. 596.5). The tire representations are located within the
minimum and maximum measurement values specified in columns 3 and 4 of
Tables A.3 of ISO 19206-3:2021(E) Annex A (incorporated by reference,
see Sec. 596.5). The terms ``rear light'' means ``taillamp,''
``retroreflector'' means ``reflex reflector,'' and ``high centre
taillight'' means ``high-mounted stop lamp.''
(d) Visual and near infrared specification. (1) The Vehicle Test
Device rear representation colors are within the ranges specified in
Tables B.2 and B.3 of ISO 19206-3:2021(E) Annex B (incorporated by
reference, see Sec. 596.5).
(2) The rear representation infrared properties of the Vehicle Test
Device are within the ranges specified in Table B.1 of ISO 19206-
3:2021(E) Annex B (incorporated by reference, see Sec. 596.5) for
wavelengths of 850 to 950 nm when measured according to the calibration
and measurement setup specified in paragraph B.3 of ISO 19206-3:2021(E)
Annex B (incorporated by reference, see Sec. 596.5).
(3) The Vehicle Test Device rear reflex reflectors, and at least 50
cm\2\ of the taillamp representations are grade DOT-C2 reflective
sheeting as specified in 49 CFR 571.108 S8.2.
(e) Radar reflectivity specifications. (1) The radar cross section
of the Vehicle Test Device is measured with it attached to the carrier
(robotic platform). The radar reflectivity of the carrier platform is
less than 0 dBm\2\ for a viewing angle of 180 degrees and over a range
of 5 to 100 m when measured according to the radar measurement
procedure specified in C.3 of ISO 19206-3:2021(E) Annex C (incorporated
by reference, see Sec. 596.5) for fixed-angle scans.
(2) The rear bumper area as shown in Table C.1 of ISO 19206-
3:2021(E) Annex C (incorporated by reference, see Sec. 596.5)
contributes to the target radar cross section.
(3) The radar cross section is assessed using radar sensor that
operates at 76 to 81 GHz and has a range of at least 5 to 100 m, a
range gate length smaller than 0.6m, a horizontal field of view of 10
degrees or more (-3dB amplitude limit), and an elevation field of view
of 5 degrees or more (-3dB amplitude).
(4) At least 92 percent of the filtered data points of the
surrogate radar cross section for the fixed vehicle angle, variable
range measurements are within the RCS boundaries defined in Sections
C.2.2.4 of ISO 19206-3:2021(E) Annex C (incorporated by reference, see
Sec. 596.5) for a viewing angle of 180 degrees when measured according
to the radar measurement procedure specified in C.3 of ISO 19206-
3:2021(E) Annex C (incorporated by reference, see Sec. 596.5) for
fixed-angle scans.
(5) Between 86 to 95 percent of the Vehicle Test Device spatial
radar cross section reflective power is with the primary reflection
region defined in Section C.2.2.5 of ISO 19206-3:2021(E) Annex C
(incorporated by reference, see Sec. 596.5) when measured according to
the radar measurement procedure specified in C.3 of ISO 19206-3:2021(E)
Annex C (incorporated by reference, see Sec. 596.5) using the angle-
penetration method.

Issued under the authority delegated in 49 CFR 1.87.
Robin Hutcheson,
Administrator.
Issued under authority delegated in 49 CFR part 1.95 and 49 CFR
501.8.
Raymond R. Posten,
Associate Administrator for Rulemaking.
[FR Doc. 2023-13622 Filed 7-5-23; 8:45 am]
BILLING CODE 4910-59-P