[Federal Register Volume 71, Number 180 (Monday, September 18, 2006)]
[Proposed Rules]
[Pages 54712-54753]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-7598]



[[Page 54711]]

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Part II





Department of Transportation





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National Highway Traffic Safety Administration



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49 CFR Parts 571 and 585



Federal Motor Vehicle Safety Standards; Electronic Stability Control 
Systems; Proposed Rule

  Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / 
Proposed Rules  

[[Page 54712]]


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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Parts 571 and 585

[Docket No. NHTSA-2006-25801]
RIN 2127-AJ77


Federal Motor Vehicle Safety Standards; Electronic Stability 
Control Systems

AGENCY: National Highway Traffic Safety Administration (NHTSA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: As part of a comprehensive plan for reducing the serious risk 
of rollover crashes and the risk of death and serious injury in those 
crashes, this document proposes to establish a new Federal motor 
vehicle safety standard (FMVSS) No. 126 to require electronic stability 
control (ESC) systems on passenger cars, multipurpose vehicles, trucks 
and buses with a gross vehicle weight rating of 4,536 Kg (10,000 
pounds) or less. ESC systems use automatic computer-controlled braking 
of individual wheels to assist the driver in maintaining control in 
critical driving situations in which the vehicle is beginning to lose 
directional stability at the rear wheels (spin out) or directional 
control at the front wheels (plow out).
    Based on our own crash data studies, NHTSA estimates that the 
installation of ESC will reduce single-vehicle crashes of passenger 
cars by 34 percent and single vehicle crashes of sport utility vehicles 
(SUVs) by 59 percent, with a much greater reduction of rollover 
crashes.
    Preventing single-vehicle loss-of-control crashes is the most 
effective way to reduce deaths resulting from rollover crashes. This is 
because most loss of control crashes culminate in the vehicle leaving 
the roadway, which dramatically increases the probability of a 
rollover. NHTSA estimates that ESC has the potential to prevent 71 
percent of passenger car rollovers and 84 percent of SUV rollovers in 
single-vehicle crashes.
    NHTSA estimates that ESC would save 5,300 to 10,300 lives and 
prevent 168,000 to 252,000 injuries in all types of crashes annually if 
all light vehicles on the road were equipped with ESC systems. ESC 
systems would substantially reduce (by 4,200 to 5,400) of the more than 
10,000 deaths each year on American roads resulting from rollover 
crashes.
    About 29 percent of model year (MY) 2006 light vehicles sold in the 
U.S. were equipped with ESC, and manufacturers intend to increase the 
number of ESC installations in light vehicles to 71 percent by MY 2011. 
This rule would require a 100 percent installation rate for ESC by MY 
2012 (with exceptions for some vehicles manufactured in stages or by 
small volume manufacturers). Of the overall projected annual 5,300 to 
10,300 highway deaths and 168,000 to 252,000 injuries prevented, we 
would attribute 1,536 to 2,211 prevented fatalities (including 1,161 to 
1,445 involving rollover) to this proposed rulemaking, in addition to 
the prevention of 50,594 to 69,630 injuries.

DATES: You should submit your comments early enough to ensure that 
Docket Management receives them not later than November 17, 2006.

ADDRESSES: You may submit comments identified by DOT DMS Docket Number 
above by any of the following methods:
     Web Site: http://dms.dot.gov. Follow the instructions for 
submitting comments on the DOT electronic docket site.
     Fax: 1-202-493-2251.
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal Holidays.
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the online instructions for submitting 
comments.
    Instructions: All submissions must include the agency name and 
docket number or Regulatory Identification Number (RIN) for this 
rulemaking. 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 http://dms.dot.gov, including any personal information provided. 
Please see the Privacy Act heading under Regulatory Notices.
    Docket: For access to the docket to read background documents or 
comments received, go to http://dms.dot.gov at any time or to Room PL-
401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., 
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal Holidays.

FOR FURTHER INFORMATION CONTACT: For non-legal issues, you may call Mr. 
Patrick Boyd, Office of Crash Avoidance Standards at (202) 366-2272. 
His FAX number is (202) 366-7002.
    For legal issues, you may call Mr. Eric Stas, Office of the Chief 
Counsel at (202) 366-2992. His FAX number is (202) 366-3820.
    You may send mail to both of these officials at National Highway 
Traffic Safety Administration, 400 Seventh Street, SW., Washington, DC 
20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary
II. Safety Problems Addressed by the Proposed Standard
    A. Single-Vehicle Crash and Rollover Statistics
    B. The Agency's Comprehensive Response to Rollover
III. Electronic Stability Control Systems
    A. How ESC Prevents Loss of Vehicle Control
    B. Additional Features of Some ESC Systems
IV. Effectiveness of ESC
    A. Human Factors Study on the Effectiveness of ESC
    B. Crash Data Studies of ESC Effectiveness
V. Agency Proposal
    A. Definition of ESC
    B. Performance Test of ESC Oversteer Intervention and Stability 
Criteria
    C. Responsiveness Criteria
    D. Other Issues
    1. ESC Off Switches
    2. ESC Activation and Malfunction Symbols and Telltale
    3. ESC Off Switch Symbol and Telltale
    E. Alternatives to the Agency Proposal
VI. Leadtime
VII. Benefits and Costs
    A. Summary
    B. ESC Benefits
    C. ESC Costs
VIII. Public Participation
IX. Regulatory Analyses and Notices

I. Executive Summary

    As part of a comprehensive plan for reducing the serious risk of 
rollover crashes and the risk of death and serious injury in those 
crashes, this rule proposes to establish Federal Motor Vehicle Safety 
Standard (FMVSS) No. 126, Electronic Stability Control Systems, which 
would require passenger cars, multipurpose passenger vehicles (MPVs), 
trucks, and buses that have a gross vehicle weight rating (GVWR) of 
4,536 kg (10,000 pounds) or less to be equipped with an ESC system that 
meets the requirements of the standard. ESC systems use automatic, 
computer-controlled braking of individual wheels to assist the driver 
in maintaining control (and the vehicle's intended heading) in 
situations where the vehicle is beginning to lose directional stability 
(e.g., where the driver misjudges the severity of a curve

[[Page 54713]]

or over-corrects in an emergency situation). In such situations (which 
occur with considerable frequency), intervention by the ESC system can 
assist the driver in preventing the vehicle from leaving the roadway, 
thereby preventing fatalities and injuries associated with crashes 
involving vehicle rollover or collision with various objects (e.g., 
trees, highway infrastructure, other vehicles).
    Based upon current estimates regarding the effectiveness of ESC 
systems, we believe that an ESC standard could save thousands of lives 
each year, providing potentially the greatest safety benefits produced 
by any safety device since the introduction of seat belts. The 
following discussion highlights the research and regulatory efforts 
that have culminated in the present proposal.
    Since the early 1990's, NHTSA has been actively engaged in finding 
ways to address the problem of vehicle rollover, because crashes 
involving rollover are responsible for a disproportionate number of 
fatalities and serious injuries (over 10,000 of the 33,000 fatalities 
of vehicle occupants in 2004). Although various options were explored, 
the agency ultimately chose to add a rollover resistance component to 
its New Car Assessment Program (NCAP) consumer information program in 
2001. In response to NCAP's market-based incentives, vehicle 
manufacturers made modifications to their product lines to increase 
their vehicles' geometric stability and rollover resistance by 
utilizing wider track widths (typically associated with passenger cars) 
on many of their newer sport utility vehicles (SUVs) and by making 
other improvements to truck-based SUVs during major redesigns (e.g., 
introduction of roll stability control). This approach was successful 
in terms of reducing the much higher rollover rate of SUVs and other 
high-center-of-gravity vehicles, as compared to passenger cars. 
However, manipulating vehicle configuration alone cannot entirely 
resolve the rollover problem (particularly when consumers continue to 
demand vehicles with greater carrying capacity and higher ground 
clearance).
    Accordingly, the agency began exploring technologies that could 
confront the issue of vehicle rollover from a different perspective or 
line of inquiry, which led to today's proposal. We believe that our 
proposed ESC requirement offers a complementary approach that would 
provide substantial benefits to drivers of both passenger cars and LTVs 
(light trucks/vans). Undoubtedly, keeping vehicles from leaving the 
roadway is the best way to prevent deaths and injuries associated with 
rollover, as well as other types of crashes. Based on its crash data 
studies, NHTSA estimates that the installation of ESC systems will 
reduce single vehicle crashes of passenger cars by 34 percent and 
single vehicle crashes of sport utility vehicles (SUVs) by 59 percent. 
Its effectiveness is especially great for single-vehicle crashes 
resulting in rollover, where ESC systems were estimated to prevent 71 
percent of passenger car rollovers and 84 percent of SUV rollovers in 
single vehicle crashes (see section VII).
    In short, we believe that preventing single-vehicle loss-of-control 
crashes is the most effective way to reduce rollover deaths, and we 
believe that ESC offers considerable promise in terms of meeting this 
important safety objective while maintaining a broad range of vehicle 
choice for consumers. In fact, among the agency's ongoing and planned 
rulemakings, it is the single most effective way of reducing the total 
number of traffic deaths. It is also the most cost-effective of those 
rulemakings.
    We note that this proposal is consistent with recent congressional 
legislation contained in section 10301 of the Safe, Accountable, 
Flexible, Efficient Transportation Equity Act: A Legacy for Users of 
2005 (SAFETEA-LU).\1\ That provision requires the Secretary of 
Transportation to ``establish performance criteria to reduce the 
occurrence of rollovers consistent with stability enhancing 
technologies'' and to ``issue a proposed rule * * * by October 1, 2006, 
and a final rule by April 1, 2009.''
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    \1\ Pub. L. 109-59, 119 Stat. 1144 (2005).
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    The balance of this notice explains in detail: (1) The size of the 
safety problem (see section II); (2) how ESC systems would act to 
mitigate that safety problem (see section II); (3) the basics of ESC 
operation (see section III); (4) findings from ESC-related research 
(see section IV);(5) the specifics of our regulatory proposal (see 
section V); (6) lead time and phase-in requirements (see section VI), 
and (7) costs and benefits associated with this proposal (see section 
VII). The following section summarizes the key points of the proposal.

A. Proposed Requirements for ESC Systems

    Consistent with the congressional mandate in section 10301 of 
SAFETEA-LU, NHTSA is proposing to require all light vehicles to be 
equipped with an ESC system with, at the minimum, the capabilities of 
current production systems. We believe that a requirement for such ESC 
systems would be practicable in terms of both ensuring technological 
feasibility and providing the desired safety benefits in a cost-
effective manner. Although vehicle manufacturers have been increasing 
the share of the light vehicle fleet equipped with ESC, we believe that 
given the relatively high cost of this technology, a mandatory standard 
is necessary to maximize the safety benefits associated with electronic 
stability control, and is consistent with the mandate arising out of 
SAFETEA-LU.
    In order to realize these benefits, we have tentatively decided to 
require vehicles both to be equipped with an ESC system meeting 
definitional requirements and to pass a dynamic test. The definitional 
requirements specify the necessary elements of a stability control 
system that would be capable of both effective oversteer and understeer 
intervention. These requirements are necessary due to the extreme 
difficulty in establishing a test adequate to ensure the desired level 
of ESC functionality.\2\ The test is necessary to ensure that the ESC 
system is robust and meets a level of performance at least comparable 
to that of current ESC systems. These requirements are summarized 
below.
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    \2\ Without an equipment requirement, it would be almost 
impossible to devise a single performance test that could not be met 
through some action by the manufacturer other than providing an ESC 
system. Even a battery of performance tests still might not achieve 
our intended results, because although it might necessitate 
installation of an ESC system, we expect that it would be unduly 
cumbersome for both the agency and the regulated community.
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     Consistent with the industry consensus definition of ESC 
contained in the Society of Automotive Engineers (SAE) Surface Vehicle 
Information Report J2564 (rev. June 2004), we are proposing to require 
vehicles covered under the standard to be equipped with an ESC system 
that:
    (1) Augments vehicle directional stability by applying and 
adjusting the vehicle's brakes individually to induce correcting yaw 
torques to a vehicle;
    (2) Is computer-controlled, with the computer using a closed-loop 
algorithm \3\ to limit vehicle oversteer and to limit vehicle 
understeer when appropriate;
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    \3\ A ``closed-loop algorithm'' is a cycle of operations 
followed by a computer that includes automatic adjustments based on 
the result of previous operations or other changing conditions.

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    (3) Has a means to determine vehicle yaw rate \4\ and to estimate 
its sideslip \5\;
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    \4\ ``Yaw rate'' means the rate of change of the vehicle's 
heading angle measured in degrees/second of rotation about a 
vertical axis through the vehicle's center of gravity.
    \5\ ``Sideslip'' means the arctangent of the lateral velocity of 
the center of gravity of the vehicle divided by the longitudinal 
velocity of the center of gravity.
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    (4) Has a means to monitor driver steering input, and
    (5) Is operational over the full speed range of the vehicle (except 
below a low-speed threshold where loss of control of the vehicle is 
unlikely).
     The proposed ESC system as defined above would also be 
required to be capable of applying all four brakes individually and to 
have an algorithm that utilizes this capability. The system would also 
be required to be operational during all phases of driving, including 
acceleration, coasting, and deceleration (including braking), and it 
would be required to remain operational when the antilock brake system 
or traction control system is activated.
     We are also proposing to require vehicles covered under 
the standard to meet a performance test that would satisfy the 
standard's stability criteria and responsiveness criterion when 
subjected to the Sine with Dwell steering maneuver test. This test 
involves a vehicle coasting at an initial speed of 50 mph while a 
steering machine steers the vehicle with a steering wheel pattern as 
shown in Figure 2. The test maneuver is then repeated over a series of 
increasing maximum steering angles. This test maneuver was selected 
over a number of other alternatives, because we tentatively decided 
that it has the most optimal set of characteristics, including severity 
of the test, repeatability and reproducibility of results, and the 
ability to address lateral stability and responsiveness (see section 
V.B).
    The maneuver is severe enough to produce spinout for most vehicles 
without ESC. The stability criteria for the test measure how quickly 
the vehicle stops turning after the steering wheel is returned to the 
straight-ahead position. A vehicle that continues to turn for an 
extended period after the driver steers straight is out of control, 
which is what ESC is designed to prevent. The stability criteria are 
expressed in terms of the percent of the peak yaw rate after maximum 
steering that persists at a period of time after the steering wheel has 
been returned to straight ahead. They require that the vehicle yaw rate 
decrease to no more than 35 percent of the peak value after one second 
and that it continues to drop to no more than 20 percent after 1.75 
seconds. Since a vehicle that simply responds very little to steering 
commands could meet the stability criteria, a minimum responsiveness 
criterion is applied to the same test. It requires that the ESC-
equipped vehicle must move laterally at least 1.83 meters (half a 12 
foot lane width) during the first 1.07 seconds after the initiation of 
steering (a discontinuity in the steering pattern that is convenient 
for timing a measurement).
     Because the benefits of the ESC system can only be 
realized if the system is functioning properly, we are proposing to 
require a telltale be mounted inside the occupant compartment in front 
of and in clear view of the driver and be identified by the symbol 
shown for ``ESC Malfunction Telltale'' in Table 1 of FMVSS No. 101, 
Controls and Displays. The ESC malfunction telltale would be required 
to illuminate not more than two minutes after the occurrence of one or 
more malfunctions that affect the generation or transmission of control 
or response signals in the vehicle's ESC system. Such telltale must 
remain continuously illuminated for as long as the malfunction(s) 
exists, whenever the ignition locking system is in the ``On'' (``Run'') 
position. (Vehicle manufacturers would be permitted to use the ESC 
malfunction telltale in a flashing mode to indicate ESC operation.)
     In certain circumstances, drivers may have legitimate 
reasons to disengage the ESC system or limit its ability to intervene, 
such as when the vehicle is stuck in sand/gravel or when the vehicle is 
being run on a track for maximum performance. Accordingly, under this 
proposal, vehicle manufacturers would be permitted to include a driver-
selectable switch that places the ESC system in a mode in which it 
would not satisfy the performance requirements of the standard (e.g., 
``sport'' mode or full-off mode). However, if the vehicle manufacturer 
chooses this option, it would be required to ensure that the ESC system 
always returns to a mode that satisfies the requirements of the 
standard at the initiation of each new ignition cycle, regardless of 
the mode the driver had previously selected. The manufacturer would be 
required to provide an ``ESC Off'' switch and a telltale that is 
mounted inside the occupant compartment in front of and in clear view 
of the driver and which is identified by the symbol shown for ``ESC 
Off'' in Table 1 of FMVSS No. 101. Such telltale must remain 
continuously illuminated for as long as the ESC is in a mode that 
renders it unable to meet the performance requirements of the standard, 
whenever the ignition locking system is in the ``On'' (``Run'') 
position.
     We are not proposing to require the ESC system to be 
equipped with a roll stability control function (or a separate system 
to that effect). Roll stability control systems involve relatively new 
technology, and there is currently insufficient data to judge the 
efficacy of such systems. However, the agency will continue to monitor 
the development of roll stability control systems. Vehicle 
manufacturers may supplement the ESC system we are proposing to require 
with a roll stability control system/feature.

B. Leadtime and Phase-In

    In order to provide the public with what are expected to be the 
significant safety benefits of ESC systems as rapidly as possible, 
NHTSA is proposing to require all light vehicles covered by this 
standard to be equipped with a FMVSS No. 126-compliant ESC system by 
September 1, 2011. We are proposing that compliance would commence on 
September 1, 2008, which would mark the start of a three-year phase-in 
period. Subject to the special provisions discussed below, the proposed 
phase-in schedule for FMVSS No. 126 would be as follows: 30 percent of 
a vehicle manufacturer's light vehicles manufactured during the period 
from September 1, 2008 to August 31, 2009 would be required to comply 
with the standard; 60 percent of those manufactured during the period 
from September 1, 2009 to August 31, 2010; 90 percent of those 
manufactured during the period from September 1, 2010 to August 31, 
2011, and all light vehicles thereafter.
    In general, we believe that it would be practicable for vehicle 
manufacturers to meet the requirements of the phase-in discussed above. 
We anticipate that vehicle manufacturers would be able to meet the 
requirements of the proposed standard by installing ESC systems 
currently in production, and most vehicle lines would likely experience 
some level of redesign over the next four to five years, which would 
provide an opportunity to incorporate an ESC system during the course 
of the manufacturer's normal production cycle (see section VI for a 
more complete discussion).
    However, NHTSA is proposing to exclude multi-stage manufacturers 
and alterers from the requirements of the phase-in and to extend by one 
year the time for compliance by those manufacturers (i.e., until 
September 1, 2012). This NPRM also proposes to exclude small volume 
manufacturers

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(i.e., manufacturers producing less than 5,000 vehicles for sale in the 
U.S. market in one year) from the phase-in, instead requiring such 
manufacturers to fully comply with the standard on September 1, 2011.
    Under our proposal, vehicle manufacturers would be permitted to 
earn carry-forward credits for compliant vehicles, produced in excess 
of the phase-in requirements, which are manufactured between the 
effective date of the final rule and the conclusion of the phase-in 
period.\6\
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    \6\ We note that carry-forward credits would not be permitted to 
be used to defer the mandatory compliance date of September 1, 2011 
for all covered vehicles.
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C. Anticipated Impacts of the Proposal

    As noted above, we believe that ESC has among the highest life-
saving potential of any vehicle safety device developed in the past 
three decades, ranking with seatbelts and air bags in terms of 
importance. NHTSA estimates that ESC would save 5,300 to 10,300 lives 
and prevent 168,000 to 252,000 injuries in all types of crashes annuvly 
if all light vehicles on the road were equipped with ESC systems. A 
large portion of these savings would come from rollover crashes. ESC 
systems would substantially reduce (by 4,200 to 5,400) of the more than 
10,000 deaths each year on American roads resulting from rollover 
crashes.
    About 29 percent of model year (MY) 2006 light vehicles sold in the 
U.S. were equipped with ESC, and manufacturers intend to increase the 
number of ESC installations in light vehicles to 71 percent by MY 
2011.\7\ This rule would require a 100 percent installation rate for 
ESC by MY 2012 (with exceptions for some vehicles manufactured in 
stages or by small volume manufacturers). As the discussion below 
demonstrates, ESC has very significant life-saving and injury-
preventing potential in absolute terms, but it does so in a very cost-
effective manner vis-a-vis other agency rulemakings. ESC offers 
consistently strong benefits and cost-effectiveness across all types of 
light vehicles, including passenger cars, SUVs, vans, and pick-up 
trucks.
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    \7\ In April 2006, NHTSA sent letters to seven vehicle 
manufacturers requesting voluntary submission of information 
regarding their planned production of ESC-equipped vehicles for 
model years 2007 to 2012. Manufacturers responded with product plans 
containing confidential information. These agency letters and 
manufacturer responses (with confidential information redacted) may 
be found in the docket for this rulemaking.
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    Of the 5,300 to 10,300 highway deaths and 168,000 to 252,000 MAIS 
1-5 injuries which we project will be prevented annually for all types 
of crashes once all light vehicles on the road are equipped with ESC, 
we would attribute 1,536 to 2,211 prevented fatalities (including 1,161 
to 1,445 involving rollover) to this proposed rulemaking, in addition 
to the prevention of 50,594 to 69,630 injuries. This compares favorably 
with the Regulatory Impact Analyses for other important rulemakings 
such as FMVSS No. 208 mandatory air bags (1,964 to 3,670 lives saved), 
FMVSS No. 214 side impact protection (690 to 1,030 lives saved), and 
FMVSS No. 201 upper interior head impact protection (870 to 1,050 lives 
saved). (See section VII, Benefits and Costs of this notice and the 
Preliminary Regulatory Impact Analysis submitted to the docket for this 
rulemaking). In addition, the agency estimates that property damage and 
travel delay costs would be reduced by $260 to $453 million annually.
    The agency estimates that the production-weighted, average cost per 
vehicle to meet the proposed standard's requirements would be $58 
($90.3 per passenger car and $29.2 per light truck). These are 
incremental costs over the MY 2011 installation of ABS, which is 
expected to be installed in almost 93 percent of the light vehicle 
fleet, and ESC, which is expected to be installed in 71 percent of the 
light vehicle fleet. Vehicle costs are estimated to be $368 (in 2005$) 
for anti-lock brakes (ABS) and an additional $111 for ESC, for a total 
system cost of $479 per vehicle. Currently, every vehicle that is 
equipped with ESC, is also equipped with ABS and traction control. 
However, the agency believes that traction control is a convenience 
feature. Accordingly, it is not required by this proposal. We also 
assumed an annual production of 17 million light vehicles (9 million 
light trucks and 8 million passenger cars). Thus, the total annual 
vehicle cost of this regulation, corresponding to ESC installation 
beyond manufacturers' planned production, is expected to be 
approximately $985 million.
    In terms of cost-effectiveness, this proposal for passenger cars 
and light trucks would save 1,536 to 2,211 lives and prevent 50,594 to 
69,630 injuries at a cost of $0.19 to $0.32 million per equivalent life 
saved at a 3 percent discount rate and $0.27 to $0.43 at a 7 percent 
discount rate. Again, the cost-effectiveness for ESC compares favorably 
with the Regulatory Impact Analyses for other important rulemakings 
such as FMVSS No. 202 head restraints safety improvement ($2.61 million 
per life saved), FMVSS No. 208 center seat shoulder belts ($3.39 to 
$5.92 million per life saved), FMVSS No. 208 advanced air bags ($1.9 to 
$9.0 million per life saved), and FMVSS No. 301 fuel system integrity 
upgrade ($1.96 to $5.13 million per life saved).
    We note that the costs for passenger cars are higher because a 
greater portion of those vehicles require installation of ABS in 
addition to ESC. Nevertheless, the proposal remains highly cost-
effective even when passenger cars are considered alone. The passenger 
car portion of the proposal would save 956 lives and prevent 34,902 
injuries at a cost of $0.35 million per equivalent life saved at a 3 
percent discount rate and $0.47 at a 7 percent discount rate. 
Therefore, the agency deemed it appropriate to make the proposed 
standard applicable to all light vehicles, because such approach makes 
sense from both a safety and cost standpoint.

II. Safety Problems Addressed by the Proposed Standard

    Crash data studies conducted in the U.S., Europe and Japan indicate 
that ESC is very effective in reducing single-vehicle crashes. Studies 
of the behavior of ordinary drivers in critical situations using the 
National Advanced Driving Simulator also show a very large reduction in 
instances of loss of control when the vehicle is equipped with ESC. 
Based on its crash data studies, NHTSA estimates that ESC will reduce 
single vehicle crashes of passenger cars by 34 percent and single 
vehicle crashes of SUVs by 59 percent. NHTSA's latest crash data study 
also shows that ESC is most effective in reducing single-vehicle 
crashes that result in rollover. ESC is estimated to prevent 71 percent 
of passenger car rollovers and 84 percent of SUV rollovers in single 
vehicle crashes. It is also estimated to reduce some multi-vehicle 
crashes but at a much lower rate than its effect on single vehicle 
crashes.

A. Single-Vehicle Crash and Rollover Statistics

    About one in seven light vehicles involved in police-reported 
crashes collide with something other than another vehicle. However, the 
proportion of these single-vehicle crashes increases steadily with 
increasing crash severity, and almost half of serious and fatal 
injuries occur in single-vehicle crashes. We can describe the 
relationship between crash severity and the number of vehicles involved 
in the crash using information from the agency's crash data programs. 
We limit our discussion here to light vehicles, which consist of (1) 
passenger cars and (2) multipurpose passenger vehicles, trucks and 
buses under 4,536

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kilograms (10,000 pounds) gross vehicle weight rating (GVWR).\8\
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    \8\ For brevity, we use the term light trucks in this document 
to refer to multipurpose passenger vehicles, such as vans, minivans, 
and SUVs, trucks and buses under 4,536 kilograms (10,000 pounds) 
GVWR.
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    The 2000-2004 data from the National Automotive Sampling System 
(NASS) Crashworthiness Data System (CDS) and 2004 data from the 
Fatality Analysis Reporting System (FARS) were combined to estimate the 
current target population for this rulemaking. It includes 28,252 
people who were killed as occupants of light vehicles. Over half of 
these (15,007) occurred in single-vehicle crashes. Of these, 8,460 
occurred in rollovers. About 1.1 million injuries (AIS 1-5) occurred in 
crashes that could be affected by ESC, almost 500,000 in single vehicle 
crashes (of which almost half were in rollovers). Multi-vehicle crashes 
that could be affected by ESC accounted for 13,245 fatalities and 
almost 600,000 injuries.
    Rollover crashes are complex events that reflect the interaction of 
driver, road, vehicle, and environmental factors. We can describe the 
relationship between these factors and the risk of rollover using 
information from the agency's crash data programs.
    According to 2004 data from FARS, 10,555 people were killed as 
occupants in light vehicle rollover crashes, which represents 33 
percent of all occupants killed that year in crashes. Of those, 8,567 
were killed in single-vehicle rollover crashes. Seventy-four percent of 
the people who died in single-vehicle rollover crashes were not using a 
seat belt, and 61 percent were partially or completely ejected from the 
vehicle (including 50 percent who were completely ejected). FARS shows 
that 55 percent of light vehicle occupant fatalities in single-vehicle 
crashes involved a rollover event.
    Using data from the 2000-2004 NASS CDS files, we estimate that 
280,000 light vehicles were towed from a police-reported rollover crash 
each year (on average), and that 29,000 occupants of these vehicles 
were seriously injured. Of these 280,000 light vehicle rollover 
crashes, 230,000 were single-vehicle crashes. Sixty-two percent of 
those people who suffered a serious injury in a single-vehicle tow-away 
rollover crash were not using a seat belt, and 52 percent were 
partially or completely ejected (including 41 percent who were 
completely ejected). Estimates from NASS CDS indicate that 82 percent 
of tow-away rollovers were single-vehicle crashes, and that 88 percent 
(202,000) of the single-vehicle rollover crashes occurred after the 
vehicle left the roadway. An audit of 1992-96 NASS CDS data showed that 
about 95 percent of rollovers in single-vehicle crashes were tripped by 
mechanisms such as curbs, soft soil, pot holes, guard rails, and wheel 
rims digging into the pavement, rather than by tire/road interface 
friction as in the case of untripped rollover events.

B. The Agency's Comprehensive Response to Rollover

    As mentioned above, this proposal for ESC is part of the agency's 
comprehensive plan to address the issue of vehicle rollover. The 
following provides background on NHTSA's comprehensive plan to reduce 
rollover crashes. In 2002, the agency formed an Integrated Project Team 
(IPT) to examine the rollover problem and make recommendations on how 
to reduce rollovers and improve safety when rollovers nevertheless 
occur. In June 2003, based on the work of the team, the agency 
published a report entitled, ``Initiatives to Address the Mitigation of 
Vehicle Rollover.'' \9\ The report recommended improving vehicle 
stability, ejection mitigation, roof crush resistance, as well as road 
improvement and behavioral strategies aimed at consumer education.
---------------------------------------------------------------------------

    \9\ See Docket Number NHTSA 2003-14622-1.
---------------------------------------------------------------------------

    Since then, the agency has been working to implement these 
recommendations as part of it comprehensive agency plan for reducing 
the serious risk of rollover crashes and the risk of death and serious 
injury when rollover crashes do occur. It is evident that the most 
effective way to reduce deaths and injuries in rollover crashes is to 
prevent the rollover crash from occurring. This proposal to adopt a new 
Federal motor vehicle safety standard for electronic stability control 
systems is one part of that comprehensive agency plan.
    Moreover, we note that the agency also published a notice of 
proposed rulemaking in the Federal Register in August 2005, seeking to 
upgrade our safety standard on roof crush resistance (FMVSS No. 216); 
that notice, like the present one, contains an in-depth discussion of 
the rollover problem and the countermeasures which the agency intends 
to pursue as part of its comprehensive response to the rollover problem 
(see 70 FR 49223 (August 23, 2005)).

III. Electronic Stability Control Systems

    Although Electronic Stability Control (ESC) systems are known by 
many different trade names such as Vehicle Stability Control (VSC), 
Electronic Stability Program (ESP), StabiliTrak and Vehicle Stability 
Enhancement (VSE), their function and performance are similar. They are 
systems that uses computer control of individual wheel brakes to help 
the driver maintain control of the vehicle during extreme maneuvers by 
keeping the vehicle headed in the direction the driver is steering even 
when the vehicle nears or reaches the limits of road traction.
    When a driver attempts an ``extreme maneuver'' (e.g., one initiated 
to avoid a crash or due to misjudgment of the severity of a curve), the 
driver may lose control if the vehicle responds differently as it nears 
the limits of road traction than it does during ordinary driving. The 
driver's loss of control can result in either the rear of the vehicle 
``spinning out'' or the front of the vehicle ``plowing out.'' As long 
as there is sufficient road traction, a highly skilled driver may be 
able to maintain control in many extreme maneuvers using 
countersteering (i.e., momentarily turning away from the intended 
direction) and other techniques. However, average drivers in a panic 
situation in which the vehicle beginning to spin out would be unlikely 
to countersteer to regain control.
    ESC uses automatic braking of individual wheels to adjust the 
vehicle's heading if it departs from the direction the driver is 
steering. Thus, it prevents the heading from changing too quickly 
(spinning out) or not quickly enough (plowing out). Although it cannot 
increase the available traction, ESC affords the driver the maximum 
possibility of keeping the vehicle under control and on the road in an 
emergency maneuver using just the natural reaction of steering in the 
intended direction.
    Keeping the vehicle on the road prevents single-vehicle crashes, 
which are the circumstances that lead to most rollovers. However, if 
the speed is simply too great for the available road traction, even a 
vehicle with ESC will unavoidably drift off the road (but not spin 
out). Furthermore, ESC cannot prevent road departures due to driver 
inattention or drowsiness rather than loss of control.

A. How ESC Prevents Loss of Vehicle Control

    The following explanation of ESC operation illustrates the basic 
principle of yaw stability control, but it does not attempt to explain 
advanced refinements of the yaw control strategy described below that 
use vehicle sideslip (lateral sliding that may not alter yaw rate) to 
optimize performance on slippery pavements.

[[Page 54717]]

    An ESC system maintains what is known as ``yaw'' (or heading) 
control by determining the driver's intended heading, measuring the 
vehicle's actual response, and automatically turning the vehicle if its 
response does not match the driver's intention. However, with ESC, 
turning is accomplished by applying counter torques from the braking 
system rather than from steering input.
    Speed and steering angle measurements are used to determine the 
driver's intended heading. The vehicle response is measured in terms of 
lateral acceleration and yaw rate by onboard sensors. If the vehicle is 
responding in a manner corresponding to driver input, the yaw rate will 
be in balance with the speed and lateral acceleration.
    The concept of ``yaw rate'' can be illustrated by imaging the view 
from above of a car following a large circle painted on a parking lot. 
One is looking at the top of the roof of the vehicle and seeing the 
circle. If the car starts in a heading pointed north and drives half 
way around circle, its new heading is south. Its yaw angle has changed 
180 degrees. If it takes 10 seconds to go half way around the circle, 
the ``yaw rate'' is 180 degrees per 10 seconds or 18 deg/sec. If the 
speed stays the same, the car is constantly rotating at a rate of 18 
deg/sec around a vertical axis that can be imagined as piercing its 
roof. If the speed is doubled, the yaw rate increases to 36 deg/sec.
    While driving in a circle, the driver notices that he must hold the 
steering wheel tightly to avoid sliding toward the passenger seat. The 
bracing force is necessary to overcome the lateral acceleration that is 
caused by the car following the curve. The lateral acceleration is also 
measured by the ESC system. When the speed is doubled the lateral 
acceleration increases by a factor of four if the vehicle follows the 
same circle. There is a fixed physical relationship between the car's 
speed, the radius of its circular path, and its lateral acceleration.
    The ESC system uses this information as follows: Since the ESC 
system measures the car's speed and its lateral acceleration, it can 
compute the radius of the circle. Since it then has the radius of the 
circle and the car's speed, the ESC system can compute the correct yaw 
rate for a car following the path. Of course, the system includes a yaw 
rate sensor, and it compares the actual measured yaw rate of the car to 
that computed for the path the car is following. If the computed and 
measured yaw rates begin to diverge as the car that is trying to follow 
the circle speeds up, it means the driver is beginning to lose control, 
even if the driver cannot yet sense it. Soon, an unassisted vehicle 
would have a heading significantly different from the desired path and 
would be out of control either by oversteering (spinning out) or 
understeering.
    When the ESC system detects an imbalance between the measured yaw 
rate of a vehicle and the path defined by the vehicle's speed and 
lateral acceleration, the ESC system automatically intervenes to turn 
the vehicle. The automatic turning of the vehicle is accomplished by 
uneven brake application rather than by steering wheel movement. If 
only one wheel is braked, the uneven brake force will cause the 
vehicle's heading to change. Figure 1 shows the action of ESC using 
single wheel braking to correct the onset of oversteering or 
understeering. (Please note that all Figures discussed in this preamble 
may be found at the end of the preamble, immediately preceding the 
proposed regulatory text.)
     Oversteering. In Figure 1 (bottom panel), the vehicle has 
entered a left curve that is extreme for the speed it is traveling. The 
rear of the vehicle begins to slide which would lead to a vehicle 
without ESC turning sideways (or ``spinning out'') unless the driver 
expertly countersteers. In a vehicle equipped with ESC, the system 
immediately detects that the vehicle's heading is changing more quickly 
than appropriate for the driver's intended path (i.e., the yaw rate is 
too high). It momentarily applies the right front brake to turn the 
heading of the vehicle back to the correct path. The action happens 
quickly so that the driver does not perceive the need for steering 
corrections. Even if the driver brakes because the curve is sharper 
than anticipated, the system is still capable of generating uneven 
braking if necessary to correct the heading.
     Understeering. Figure 1 (top panel) shows a similar 
situation faced by a vehicle whose response as it nears the limits of 
road traction is to slide at the front (``plowing out'' or 
understeering) rather than oversteering. In this situation, the ESC 
system rapidly detects that the vehicle's heading is changing less 
quickly than appropriate for the driver's intended path (i.e., the yaw 
rate is too low). It momentarily applies the left rear brake to turn 
the heading of the vehicle back to the correct path.
    While Figure 1 may suggest that particular vehicles go out of 
control as either vehicles prone to oversteer or vehicles prone to 
understeer, it is just as likely that a given vehicle could require 
both understeer and oversteer interventions during progressive phases 
of a complex avoidance maneuver such as a double lane change.
    Although ESC cannot change the tire/road friction conditions the 
driver is confronted with in a critical situation, there are clear 
reasons to expect it to reduce loss-of-control crashes, as discussed 
below.
    In vehicles without ESC, the response of the vehicle to steering 
inputs changes as the vehicle nears the limits of road traction. All of 
the experience of the average driver is in operating the vehicle in its 
``linear range'', i.e., the range of lateral acceleration in which a 
given steering wheel movement produces a proportional change in the 
vehicle's heading. The driver merely turns the wheel the expected 
amount to produce the desired heading. Adjustments in heading are easy 
to achieve because the vehicle's response is proportional to the 
driver's steering input, and there is very little lag time between 
input and response. The car is traveling in the direction it is 
pointed, and the driver feels in control. However, at lateral 
accelerations above about one-half ``g'' on dry pavement for ordinary 
vehicles, the relationship between the driver's steering input and the 
vehicle's response changes (toward oversteer or understeer), and the 
lag time of the vehicle response can lengthen. When a driver encounters 
these changes during a panic situation, it adds to the likelihood that 
the driver will loose control and crash because the familiar actions 
learned by driving in the linear range would not be the correct 
steering actions.
    However, ordinary linear range driving skills are much more likely 
to be adequate for a driver of a vehicle with ESC to avoid loss of 
control in a panic situation. By monitoring yaw rate and sideslip, ESC 
can intervene early in the impending loss-of-control situation with the 
appropriate brake forces necessary to restore yaw stability before the 
driver would attempt an over correction or other error. The net effect 
of ESC is that the driver's ordinary driving actions learned in linear 
range driving are the correct actions to control the vehicle in an 
emergency. Also, the vehicle will not change its heading from the 
desired path in a way that would induce further panic in a driver 
facing a critical situation. Studies using a driving simulator, 
discussed in Section IV, demonstrate that ordinary drivers are much 
less likely to lose control of a vehicle with ESC when faced with a 
critical situation.
    Besides allowing drivers to cope with emergency maneuvers and 
slippery pavement using only ``linear range'' skills, ESC provides more 
powerful

[[Page 54718]]

control interventions than those available to even expert drivers of 
non-ESC vehicles. For all practical purposes, the yaw control actions 
with non-ESC vehicles are limited to steering. However, as the tires 
approach the maximum lateral force sustainable under the available 
pavement friction, the yaw moment generated by a given increment of 
steering angle is much less than at the low lateral forces occurring in 
regular driving.\10\. This means that as the vehicle approaches its 
maximum cornering capability, the ability of the steering system to 
turn the vehicle is greatly diminished, even in the hands of an expert 
driver. ESC creates the yaw moment to turn the vehicle using braking at 
an individual wheel rather than the steering system. This intervention 
remains powerful even at limits of tire traction because both the 
braking force of the individual tire and the reduction of lateral force 
that accompanies the braking force act to create the desired yaw 
moment. Therefore, ESC can be especially beneficial on slippery 
surfaces. While a vehicle's possibility of staying on the road in a 
critical maneuver ultimately is limited by the tire/pavement friction, 
ESC maximizes an ordinary driver's ability to use the available 
friction.
---------------------------------------------------------------------------

    \10\ Liebemann et al., (2005) Safety and Performance 
Enhancement: The Bosch Electronic Stability Control (ESP), 19th 
International Technical Conference on the Enhanced Safety of 
Vehicles (ESV), Washington, DC.
---------------------------------------------------------------------------

B. Additional Features of Some ESC Systems

    In addition to the basic operation of ``yaw stability control'', 
many ESC systems include additional features. For example, most systems 
reduce engine power during intervention to slow the vehicle and give it 
a better chance of being able to stay on the intended path after its 
heading has been corrected.
    Other ESC systems may go further by performing high deceleration 
automatic braking at all four wheels. Of course, such braking would be 
performed unevenly side to side so that the same net yaw torque or 
``turning force'' would be applied to the vehicle as in the basic case 
of single-wheel braking.
    ESC systems used on vehicles with a high center of gravity (c.g.), 
such as SUVs, are often programmed to perform an additional function 
known as ``roll stability control.'' Roll stability control (RSC) is a 
direct countermeasure for on-pavement rollover crashes of high c.g. 
vehicles. Some RSC systems measure the roll angle of the vehicle using 
an additional roll rate sensor to determine if the vehicle is in danger 
of tipping up. Other systems rely on the existing ESC sensors for 
steering angle, speed, and lateral acceleration, along with knowledge 
of vehicle-specific characteristics to estimate whether the vehicle is 
in danger of tipping up.
    Regardless of the method used to detect the risk of tip-up, the 
various types of roll stability control intervene in the same way. 
Specifically, they intervene by reducing lateral acceleration which is 
the cause of the roll motion of the vehicle on its suspension, thus 
preventing the possibility of it rolling so much that the inside wheels 
may lift off the pavement. The intervention is performed the same way 
as the oversteer intervention shown in the Figure 1. The outside front 
brake is applied heavily to turn the vehicle toward a path of less 
curvature and, therefore, less lateral acceleration.
    The difference between a roll stability control intervention and an 
oversteer intervention by the ESC system operating in the basic yaw 
stability control mode is the triggering circumstance. The oversteer 
intervention occurs when the vehicle's excessive yaw rate indicates 
that its heading is departing from the driver's intended path, but the 
roll stability control intervention occurs when there is a risk the 
vehicle could roll over. Thus, the roll stability control intervention 
occurs when the vehicle is still following the driver's intended path. 
The obvious trade-off of roll stability control is that the vehicle 
must depart to some extent from the driver's intended path in order to 
reduce the lateral acceleration from the level that could cause tip-up.
    If the determination of impending rollover that triggers the roll 
stability intervention is very certain, then the possibility of the 
vehicle leaving the roadway as a result of the roll stability 
intervention represents a lower relative risk to the driver. Obviously, 
systems that intervene only when absolutely necessary and then with the 
minimum loss of lateral acceleration to prevent rollover are the most 
effective. However, roll stability control is a new technology that is 
still evolving. Roll stability control is not a subject of this 
rulemaking because it is too soon for actual crash statistics to 
illuminate its practical effect on crash reduction.

IV. Effectiveness of ESC

    Electronic stability control can directly reduce a vehicle's 
susceptibility to on-road untripped rollovers as measured by the 
``fishhook'' test that is part of NHTSA's NCAP rollover rating program. 
The direct effect is mostly limited to untripped rollovers on paved 
surfaces. However, untripped on-road rollovers are a relatively 
infrequent type of rollover crash. In contrast, the vast majority of 
rollover crashes occur when a vehicle runs off the road and strikes a 
tripping mechanism such as soft soil, a ditch, a curb or a guardrail.
    We expect that requiring ESC to be installed on light trucks and 
passenger cars would result in a large reduction in the number of 
rollover crashes by greatly reducing the number of single-vehicle 
crashes. As noted previously, over 80 percent of rollovers are the 
result of a single-vehicle crash. The purpose of ESC is to assist the 
driver in keeping the vehicle on the road during impending loss-of-
control situations. In this way, it can prevent the exposure of 
vehicles to off-road tripping mechanisms. We note, however, that this 
yaw stability function of ESC is not direct ``rollover resistance'' and 
cannot be measured by the NCAP rollover resistance rating.
    Although ESC is an indirect countermeasure to prevent rollover 
crashes, we believe it is the most powerful countermeasure available to 
address this serious risk. Effectiveness studies by NHTSA and others 
worldwide \11\ estimate that ESC reduces single vehicle crashes by at 
least a third in passenger cars and perhaps reduces loss-of-control 
crashes (e.g., road departures leading to rollovers) by an even greater 
amount. In fact, NHTSA's latest data study that is discussed in this 
section found a reduction in single-vehicle crashes leading to rollover 
of 71 percent for passenger cars and 84 percent for SUVs. Thus, ESC can 
reduce the numbers of rollovers of all vehicles, including lower center 
of gravity vehicles (e.g., passenger cars, minivans and two-wheel drive 
pickup trucks), as well as of the higher center of gravity vehicle 
types (e.g., SUVs and four-wheel drive pickup trucks). ESC can affect 
both crashes that would have resulted in rollover as well as other 
types of crashes

[[Page 54719]]

(e.g., road departures resulting in impacts) that result in deaths and 
injuries.

A. Human Factors Study on the Effectiveness of ESC
---------------------------------------------------------------------------

    \11\ Aga M, Okada A. (2003) Analysis of Vehicle Stability 
Control (VSC)'s Effectiveness from Accident Data, 18th International 
Technical Conference on the Enhanced Safety of Vehicles (ESV), 
Nagoya.
    Dang, J. (2004) Preliminary Results Analyzing Effectiveness of 
Electronic Stability Control (ESC) Systems, Report No. DOT HS 809 
790. U.S. Dept. of Transportation, Washington, DC.
    Farmer, C. (2004) Effect of Electronic Stability Control on 
Automobile Crash Risk, Traffic Injury Prevention Vol 5:317-325.
    Kreiss J-P, et al. (2005) The Effectiveness of Primary Safety 
Features in Passenger Cars in Germany. 19th International Technical 
Conference on the Enhanced Safety of Vehicles (ESV), Washington, DC
    Lie A., et al. (2005) The Effectiveness of ESC (Electronic 
Stability Control) in Reducing Real Life Crashes and Injuries. 19th 
International Technical Conference on the Enhanced Safety of 
Vehicles (ESV), Washington, DC.
---------------------------------------------------------------------------

    A study by the University of Iowa using the National Advanced 
Driving Simulator demonstrated the effect of ESC on the ability of 
ordinary drivers to maintain control in critical situations.\12\ A 
sample of 120 drivers equally divided between men and women and between 
three age groups (18-25, 30-40, and 55-65) was subjected to the 
following three critical driving scenarios. The ``Incursion Scenario'' 
forced drivers to attempt a double lane change at high speed (65 mph 
speed limit signs) by presenting them first with a vehicle that 
suddenly backs into their lane from a driveway and then with another 
vehicle driving toward them in the left lane. The ``Curve Departure 
Scenario'' presented drivers with a constant radius curve that was 
uneventful at the posted speed limit of 65 mph followed by another 
curve that appeared to be similar but that had a decreasing radius that 
was not evident upon entry. The ``Wind Gust Scenario'' presented 
drivers with a sudden lateral wind gust of short duration that pushed 
the drivers toward a lane of oncoming traffic. The 120 drivers were 
further divided evenly between two vehicles, a SUV and a midsize sedan. 
Half the drivers of each vehicle drove with ESC enabled, and half drove 
with ESC disabled.
---------------------------------------------------------------------------

    \12\ Papelis et al. (2004) Study of ESC Assisted Driver 
Performance Using a Driving Simulator, Report No. N04-003-PR, 
University of Iowa.
---------------------------------------------------------------------------

    In 50 of the 179 test runs performed in a vehicle without ESC, the 
driver lost control. In contrast, in only six of the 179 test runs 
performed in a vehicle with ESC, did the driver lose control. One test 
run in each ESC status had to be aborted. These results demonstrate an 
88 percent reduction in loss-of-control crashes when ESC was engaged. 
The study also concluded that the presence of an ESC system helped 
reduce loss of control regardless of age or gender, and that the 
benefit was substantially the same for the different driver subgroups 
in the study. Because of the obvious danger to participants, an 
experiment like this cannot be performed safely with real vehicles on 
real roads. However, the National Advanced Driver Simulator provides 
extraordinary verisimilitude with the driver sitting in a real vehicle, 
seeing a 360-degree scene and experiencing the linear and angular 
accelerations and sounds that would occur in actual driving of the 
specific vehicle.

B. Crash Data Studies of ESC Effectiveness

    There have been a number of studies of ESC effectiveness in Europe 
and Japan beginning in 2003 \13\. All of them have shown large 
potential reductions in single vehicle crashes as a result of ESC. 
However, the sample sizes of crashes of vehicles new enough to have ESC 
tended to be small in these studies. A preliminary NHTSA study 
published in September 2004 \14\ of crash data from 1997-2003 found ESC 
to be effective in reducing single-vehicle crashes, including rollover. 
Among vehicles in the study, the results suggested that ESC reduced 
single vehicle crashes in passenger cars by 35 percent and in SUVs by 
67 percent. In October 2004, the Insurance Institute for Highway Safety 
(IIHS) released the results of a study of the effectiveness of ESC in 
preventing crashes of cars and SUVs. The IIHS found that ESC is most 
effective in reducing fatal single-vehicle crashes, reducing such 
crashes by 56 percent. NHTSA's later peer-reviewed study \15\ of ESC 
effectiveness found that that ESC reduced single vehicle crashes in 
passenger cars by 34 percent and in SUVs by 59 percent, and that its 
effectiveness was greatest in reducing single vehicle crashes resulting 
in rollover (71 percent reduction for passenger cars and an 84 percent 
reduction for SUVs). It also found reductions in fatal single-vehicle 
crashes and fatal single-vehicle rollover crashes that were 
commensurate with the overall crash reductions cited. ESC reduced fatal 
single-vehicle crashes in passenger cars by 35 percent and in SUVs by 
67 percent and reduced fatal single-vehicle crashes involving rollover 
by 69 percent in passenger cars and 88 percent in SUVs.
---------------------------------------------------------------------------

    \13\ See Footnote 10.
    \14\ Dang, J. (2004) Preliminary Results Analyzing Effectiveness 
of Electronic Stability Control (ESC) Systems, Report No. DOT HS 809 
790. U.S. Dept. of Transportation, Washington, DC.
    \15\ Dang, J. (2006) Statistical Analysis of The Effectiveness 
of Electronic Stability Control (ESC) Systems, U.S. Dept. of 
Transportation, Washington, DC (publication pending peer review). A 
draft version of this report, as supplied to peer reviewers, has 
been placed in the docket for this rulemaking.
---------------------------------------------------------------------------

(a) NHTSA's Preliminary Study
    In September, 2004, NHTSA issued an evaluation note on the 
Preliminary Results Analyzing the Effectiveness of Electronic Stability 
Control (ESC) Systems. The study evaluated the effectiveness of ESC in 
reducing single vehicle crashes in various domestic and imported cars 
and SUVs. It was based on Fatality Analysis Reporting System (FARS) 
data from calendar years 1997-2003 and crash data from five States that 
reported partial Vehicle Identification Number (VIN) information in 
their data files (Florida, Illinois, Maryland, Missouri, and Utah) from 
calendar years 1997-2002. The data were limited to mostly luxury 
vehicles because ESC first became available in 1997 in luxury vehicles 
such as Mercedes-Benz and BMW. The analysis compared specific make/
models of passenger cars and SUVs with ESC versus earlier versions of 
the same make/models, using multi-vehicle crash involvements as a 
control group.
    The passenger car sample consisted of mainly Mercedes-Benz and BMW 
models (61 percent). Mercedes-Benz installed ESC in certain luxury 
models in 1997 and had made it standard equipment in all their models 
(except one) by 2000. BMW also installed ESC in certain 5, 7, and 8 
series models as early as 1997 and had made it standard equipment in 
all their models by 2001. The passenger car sample also included some 
luxury GM cars, which constituted 23 percent of the sample, and a few 
cars from other manufacturers. GM cars where ESC was offered as 
standard equipment are the Buick Park Avenue Ultra, the Cadillac 
DeVille, Seville STS and SLS, the Oldsmobile Aurora, the Pontiac 
Bonneville SSE and SSEi, and the Chevrolet Corvette. The SUV make/
models in the study with ESC include Mercedes-Benz (ML320, ML350, 
ML430, ML500, G500, G55 AMG), Toyota (4Runner, Landcruiser), and Lexus 
(RX300, LX470).
    The first set of analyses used multi-vehicle crash involvements as 
a control group, essentially assuming that ESC has no effect on multi-
vehicle crashes. Specific make/models with ESC were compared with 
earlier versions of similar make/models using multi-vehicle crash 
involvements as a control group, creating 2x2 contingency tables as 
shown in Tables 1 and 2. The study found that single vehicle crashes 
were reduced by

1 - {(699/1483)/(14090/19444){time}  = 35 percent

for passenger cars and by 67 percent for SUVs (Table 1). Similarly, 
fatal single vehicle crashes were reduced by 30 percent in cars and by 
63 percent in SUVs (Table 2). Reductions of single vehicle crashes in 
passenger cars and SUVs were statistically significant at the .01 
level, as evidenced by chi-square statistics exceeding 6.64 in each 2x2 
contingency table (Table 1). Reductions of fatal single vehicle crashes 
are statistically significant at the .01 level in SUVs and at the .05 
level in passenger

[[Page 54720]]

cars with chi-square statistic greater than 3.84 (Table 2).

  Table 1.--Effectiveness of ESC in Reducing Single Vehicle Crashes in
                         Passenger Cars and SUVs
     [Preliminary Study with 1997-2002 crash data from five States]
------------------------------------------------------------------------
                                                           Multi-Vehicle
                                      Single  Vehicle         Crashes
                                          Crashes            (control
                                                              group)
------------------------------------------------------------------------
Passenger Cars:
    No ESC.......................  1483.................           19444
    ESC..........................  699..................           14090
    Percent reduction in single    35%..................  ..............
     vehicle crashes in passenger
     cars with ESC.
    Approximate 95 percent         29% to 41%...........  ..............
     confidence bounds.
    Chi-square value.............  84.1.................  ..............
SUVs:
    No ESC.......................  512..................            6510
    ESC..........................  95...................            3661
    Percent reduction in single    67%..................  ..............
     vehicle crashes in SUVs with
     ESC.
    Approximate 95 percent         60% to 74%...........  ..............
     confidence bounds.
    Chi-square value.............  104.4................  ..............
------------------------------------------------------------------------


 Table 2.--Effectiveness of ESC in Reducing Fatal Single Vehicle Crashes
                       in Passenger Cars and SUVs
              [Preliminary Study with 1997-2003 FARS data]
------------------------------------------------------------------------
                                                           Fatal Multi-
                                                              Vehicle
                                    Fatal Single Vehicle      Crashes
                                          Crashes            (control
                                                              group)
------------------------------------------------------------------------
Passenger Cars:
    No ESC.......................  186..................             330
    ESC..........................  110..................             278
    Percent reduction in fatal     30%..................  ..............
     single vehicle crashes in
     passenger cars with ESC.
    Approximate 95 percent         10% to 50%...........  ..............
     confidence bounds.
    Chi-square value.............  6.0..................  ..............
SUVs:
    No ESC.......................  129..................             199
    ESC..........................  25...................             103
    Percent reduction in fatal     63%..................  ..............
     single vehicle crashes in
     SUVs with ESC.
    Approximate 95 percent         44% to 81%...........  ..............
     confidence bounds.
    Chi-square value.............  16.1.................  ..............
------------------------------------------------------------------------

(b) NHTSA's Updated Study
    NHTSA has now updated and modified last year's report, extending it 
to model year 1997-2004 vehicles--and to calendar year 2004 for the 
FARS analysis and calendar year 2003 for the State data analysis. 
Nevertheless, even as of 2004, a large proportion of the vehicles 
equipped with ESC were still luxury vehicles. Moreover, only passenger 
cars and SUVs had been equipped with ESC--no pickup trucks or minivans.
    The state databases included crash cases from California (2001-
2003), Florida (1997-2003), Illinois (1997-2002), Kentucky (1997-2002), 
Missouri (1997-2003), Pennsylvania (1997-2001, 2003), and Wisconsin 
(1997-2003). The FARS database included fatal crash involvements from 
calendar years 1997 to 2004. The extra year of exposure and the 
availability of data from more states significantly increased the 
sample size of crashes of vehicles with ESC. In the preliminary study, 
the state crash database contained 699 single-vehicle crashes of cars 
with ESC and 95 single-vehicle crashes of SUVs with ESC. The FARS 
database contained 110 single-vehicle crashes of cars with ESC and 25 
single-vehicle crashes of SUVs with ESC. For the updated study, the 
state crash database contains 2,251 single-vehicle crashes of cars with 
ESC and 553 single-vehicle crashes of SUVs with ESC, and the FARS 
database of fatal single-vehicle crashes contains 157 and 47 crashes 
respectively, for passenger cars and SUVs with ESC.
    The larger sample of crashes in the updated study facilitated a new 
analysis of the effectiveness of ESC on specific subsets of single-
vehicle crashes (SV run-off-road crashes and SV crashes resulting in 
rollover). It also facilitated the use of a more focused control group 
of crashes that were unlikely to be affected by ESC so that a new 
analysis of the effect of ESC on multi-vehicle crashes could be 
undertaken.
    The basic analytical approach was to estimate the reduction of 
crash involvements of the types that are most likely to have benefited 
from ESC--relative to a control group of other types of crashes where 
ESC is unlikely to have made a difference in the vehicle's involvement. 
Crash types taken as the new control group (non-relevant involvements 
because ESC would in almost all cases not have prevented the crash) 
were crash involvements in which a vehicle:
    (1) Was stopped, parked, backing up, or entering/leaving a parking 
space prior to the crash,
    (2) Traveled at a speed less than 10 mph,
    (3) Was struck in the rear by another vehicle, or
    (4) Was a non-culpable party in a multi-vehicle crash on a dry 
road.
    The types of crash involvements where ESC would likely or at least 
possibly have an effect are:

[[Page 54721]]

    (1) All single vehicle crashes, except those with pedestrians, 
bicycles, or animals (SV crashes).
    (2) Single vehicles crashes in which a vehicle ran off the road (SV 
ROR) and hit a fixed object and/or rolled over.
    (3) Single vehicles crashes in which a vehicle rolled over (SV 
Rollover), mostly a subset of SV ROR.
    (4) Involvements as a culpable party in a multi-vehicle crash on a 
dry or wet road (MV Culpable).
    (5) Collisions with pedestrians, bicycles, or animals (Ped, Bike, 
Animal).
    In the updated study we performed the state data analysis 
separately for each state. Then we used the median of the estimates 
from the seven states as the best indicator of the central tendency of 
the data, and the variation of the seven states as a basis for judging 
statistical significance and estimating confidence bounds. The results 
of this analysis are presented in Table 3.

   Table 3.--Updated Study--Mean Effectiveness of ESC in Reducing Crashes in Passenger Cars and SUVs Based on Separate Analyses of 1997-2003 Crash Data
                                                                    From Seven States
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                    SV crashes          SV ROR          SV rollover       MV culpable                   Ped, bike, animal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Passenger Cars:
    Mean percent reduction of    34%.............  46%.............  71%.............  11%.............  34%
     listed crash type in
     passenger cars with ESC.
    Approximate 90 percent       20% to 46%......  35% to 55%......  60% to 78%......  4% to 18%.......  5% to 55%.
     confidence bounds.
SUVs:
    Mean percent reduction of    59%.............  75%.............  84%.............  16%.............  -4% not statistically significant.
     listed crash type in SUVs
     with ESC.
    Approximate 90 percent       47% to 68%......  68% to 80%......  75% to 90%......  7% to 24%.......  -28% to 15%.
     confidence bounds.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Fatal crashes were analyzed separately using the FARS database as 
was done in the preliminary study, but larger sample sizes were 
possible because of an additional year of data. The results are given 
in Table 4.

              Table 4.--Updated Study-Effectiveness of ESC in Reducing Fatal Crashes of Passenger Cars and SUVs Based on 1997-2004 FARS Data
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                      SV crashes              SV ROR              SV rollover         MV culpable     Ped, bike, animal   Control group
--------------------------------------------------------------------------------------------------------------------------------------------------------
Passenger Cars:
    No ESC.....................  223.................  217.................  36..................  176..............  46...............              166
    ESC........................  157.................  154.................  12..................  156..............  69...............              181
    Percent reduction of listed  35%.................  36%.................  69%.................  19% not            -38% not           ...............
     crash type in passenger                                                                        statistically      statistically
     cars with ESC.                                                                                 significant.       significant.
    Approximate 90 percent       20% to 51%..........  19% to 51%..........  52% to 87%..........  -2% to 39%.......  -87% to 12%......  ...............
     confidence bounds.
    Chi-square value...........  8.58................  8.17................  12.45...............  1.82.............  2.14.............  ...............
SUVs:
    No ESC.....................  197.................  191.................  106.................  108..............  56...............              153
    ESC........................  47..................  38..................  9...................  48...............  40...............              109
    Percent reduction of listed  67%.................  72%.................  88%.................  38%..............  0% not             ...............
     crash type in SUVs with                                                                                           statistically
     ESC.                                                                                                              significant.
    Approximate 90 percent       55% to 78%..........  62% to 82%..........  81% to 95%..........  16% to 60%.......  -40% to 40%......  ...............
     confidence bounds.
    Chi-square.................  29.57...............  36.44...............  42.4................  4.89.............  0.00.............  ...............
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The effectiveness of ESC in reducing fatal single-vehicle crashes 
is similar to the effectiveness in reducing single-vehicle crashes from 
state data that included mostly non-fatal crashes. In the case of fatal 
crashes as well, the effectiveness of ESC in reducing single-vehicle 
rollover crashes was particularly high. The effectiveness of ESC in 
reducing fatal culpable multi-vehicle crashes of SUVs was also higher 
than in the analysis of state data, and the parallel analysis of multi-
vehicle crashes of passenger cars did not achieve statistical 
significance.
    The updated study of ESC effectiveness yielded robust results. The 
analysis of state data and a separate analysis of fatal crashes both 
reached similar conclusions on ESC effectiveness. ESC reduced single 
vehicle crashes of passenger cars by 34 percent and single vehicle 
crashes of SUVs by 59 percent. The separate analysis of only fatal 
crashes supported the analysis of state data that included mostly non-
fatal crashes. Therefore, the overall crash reductions demonstrated a 
significant life-saving potential for this technology. The 
effectiveness of ESC in reducing SV crashes shown in the latest data 
(Tables 3-4) is similar to the results of the preliminary analysis.

[[Page 54722]]

    The effectiveness of ESC tended to be at least as great and 
possibly even greater for more severe crashes. Furthermore, the 
effectiveness of ESC in reducing the most severe type of crash in the 
study, the single-vehicle rollover crash, was remarkable. ESC reduced 
single-vehicle rollover crashes of passenger cars by 71 percent and of 
SUVs by 84 percent. This high level of effectiveness also carried over 
to fatal single-vehicle rollover crashes.
    The benefits presented in Section VII were calculated on the basis 
of the single-vehicle crash and single-vehicle rollover crash 
effectiveness results of Table 3 for reductions in non-fatal crashes 
and of Table 4 for reductions in fatal crashes. The single-vehicle 
rollover crash effectiveness results were applied only to first harmful 
event rollovers with the lower single-vehicle crash effectiveness 
results applied to all other rollover crashes for a more conservative 
benefit estimate.

V. Agency Proposal

    As discussed in detail in section VII, NHTSA's crash data study 
leads to the conclusion that an ESC requirement for light vehicles 
would save 1,536 to 2,211 lives annually once all light vehicles have 
ESC. The level of life saving associated with ESC would be second only 
to seatbelts among the items of equipment or elements of design 
regulated by the Federal motor vehicle safety standards. It is further 
estimated that an ESC requirement would prevent between 50,594 and 
69,630 MAIS 1-5 injuries annually. The life saving benefits of ESC are 
considered very cost effective with a cost per equivalent fatality of 
$0.19 million under the most favorable assumptions and $0.43 million 
under the least favorable assumptions.
    In order to capture these significant safety benefits NHTSA is 
proposing to establish FMVSS No. 126, Electronic Stability Control 
Systems, which would require passenger cars, light trucks and buses 
that have a GVWR under 4,536 Kg (10,000 lbs) GVWR to be equipped with 
an ESC system with a yaw stability control function equal to that of 
vehicles in current production. The benefits demonstrated by NHTSA's 
crash data studies and sought by the proposed safety standard are the 
result of yaw stability control greatly reducing single-vehicle crashes 
and reducing some multi-vehicle crashes as well. None of the study 
vehicles was equipped with a roll stability control system. Thus, we 
are proposing equipment requirements that are met by every ESC-equipped 
vehicle in current production and performance requirements that we 
believe are met by about 98 percent of ESC-equipped vehicles in current 
production and will require nothing more than slight retuning of the 
other two percent.
    We are not proposing a roll stability control system because there 
are no data currently available to determine the effect of roll 
stability control on crashes. However, vehicle manufacturers may 
supplement the proposed ESC systems with roll stability control.
    As proposed, FMVSS No. 126 would incorporate both an equipment 
requirement and a performance requirement. Specifically, we are 
proposing an equipment requirement for ESC that would define the 
necessary elements of a yaw stability control system capable of 
effective oversteer and understeer interventions. The ESC equipment 
requirement is augmented by a performance test of the system's 
oversteer intervention. We believe that an equipment requirement is 
necessary because establishing performance tests that would ensure that 
the ESC system operates under all road conditions and phases of driving 
is impractical. The number of tests would be immense, and many tests 
(particularly those using slippery surfaces) would not be repeatable 
enough for an objective regulation. A test requirement for understeer 
mitigation is particularly problematic because the understeer 
mitigation for many light trucks is programmed to occur only on 
slippery surfaces to avoid potential roll instability.
    The proposed standard includes a performance test of oversteer 
intervention conducted with a single highly repeatable maneuver 
performed on dry pavement over a range of steering angles with an 
automated steering machine. It is designed to ensure that the 
performance of the system is comparable to current production systems 
under a limited set of conditions that are optimal for repeatable 
testing, and it proves that the ESC system is programmed to perform its 
most basic task under ideal conditions.
    Most vehicles without ESC will spin out in this maneuver; so, a 
vehicle that avoids spin-out according to our objective yaw rate decay 
definition demonstrates that it has an ESC system typical of 2006 
production vehicles. However, the maneuver is not so extreme that every 
vehicle without ESC will actually spin out. A few non-ESC vehicles will 
pass this particular maneuver test, however they would certainly spin 
out on slippery surfaces. Therefore, the test without the definition 
does not assure the safety benefits of ESC.
    All model year 2006 vehicles with ESC systems would satisfy the 
definitional requirements of the standard. Of the sixty-two ESC 
vehicles tested by NHTSA or the Alliance of Automobile Manufacturers 
(Alliance), whose test fleet supplemented NHTSA's, only one would need 
minor reprogramming to pass the performance test.
    Some of the older vehicles in NHTSA's crash data study would not 
pass the proposed requirements (e.g., among the early ESC systems, 
there were some that were not capable of understeer intervention). 
Nevertheless, over 85 percent of the data in NHTSA's study represent 
vehicles (1998-2003 model years) that we believe would satisfy the 
proposed requirements of the new safety standard. The study vehicles 
that did not satisfy the proposed standard had systems that were 
beneficial but less effective than the average.

A. Definition of ESC

    The Society of Automotive Engineers (SAE) Surface Vehicle 
Information Report on Automotive Stability Enhancement Systems J2564 
Rev JUN2004 provides an industry consensus definition of an ESC system. 
The definition in paragraph 4.6 of SAE J2564 specifies that a ESC 
system:

    (a) Is computer controlled and the computer contains a closed-
loop algorithm \16\ designed to limit understeer and oversteer of 
the vehicle.
---------------------------------------------------------------------------

    \16\ A closed-loop algorithm is a cycle of operations followed 
by a computer that includes automatic adjustments based on the 
result of previous operations or other changing conditions.
---------------------------------------------------------------------------

    (b) Has a means to determine vehicle yaw velocity and sideslip.
    (c) Has a means to monitor driver steering input.
    (d) Has a means of applying and adjusting the vehicle brakes to 
induce correcting yaw torques to the vehicle.
    (e) Is operational over the full speed range of the vehicle 
(except below a low-speed threshold where loss of control is 
unlikely).

    We believe the SAE definition is a good basis for the proposed 
equipment requirement but that it requires minor clarifications to 
adequately describe current production systems. The definition that 
NHTSA proposes contains changes in paragraphs (a) and (b). Paragraph 
(a) has been changed to read: ``(a) is computer controlled with the 
computer using a closed-loop algorithm to limit vehicle oversteer and 
to limit vehicle understeer when appropriate.''

[[Page 54723]]

    This change recognizes that while all current ESC systems 
constantly limit oversteer, many of the systems used on vehicles with a 
high center of gravity only limit understeer on slippery surfaces where 
there is no danger that the understeer intervention could increase the 
possibility of tip-up. We also changed the expression about the 
``computer containing the algorithm'' to refer to the ``computer using 
the algorithm'' to reduce ambiguity. Furthermore, we note that 
``limiting'' understeer and oversteer means keeping those conditions 
within bounds that allow ordinary drivers to maintain control of the 
vehicle in critical situations. It does not mean reducing understeer 
and oversteer to zero under all circumstances because that is an 
impossibility, certainly not representative of production ESC systems.
    Paragraph (b) has been changed to read: ``(b) has a means to 
determine the vehicle's yaw rate and to estimate its side slip. A 
distinction has been made between the ways yaw rate and side slip are 
obtained.'' Current ESC systems use sensors to measure yaw rate, 
constituting an actual determination of this crucial metric, but they 
estimate rather than measure side slip.
    Also, the term ``yaw velocity'' has been changed to ``yaw rate'' 
because that is the term used in our research reports. Both terms have 
the same meaning.
    The SAE document also defines four categories of ESC systems: Two 
wheel and four wheel systems, each with or without engine control. The 
minimum system capable of understeer and oversteer intervention is the 
four-wheel system without engine control. SAE describes systems in this 
category as having the following attributes:
    (a) The system must have means to apply all four brakes 
individually and a control algorithm, which utilizes this capability.
    (b) The system must be operational during all phases of driving 
including acceleration, coasting, and deceleration (including braking).
    (c) The system must stay operational when ABS or Traction Control 
are activated.
    The proposed regulatory language would require an ESC system that 
combines the SAE definition with the minor clarifications discussed and 
the attributes of the four-wheel system without engine control. Nothing 
in the regulatory language conflicts with systems that employ engine 
control.
    In addition, the proposed regulatory language supplements the ESC 
equipment definition with a test of oversteer intervention which would 
define the minimum intensity of the oversteer intervention under 
certain test conditions. The test is performed with the vehicle 
coasting on a dry pavement with a high coefficient of friction. The 
test conditions are very narrow in comparison with the operational 
conditions specified in the equipment definition, but they are 
necessary to produce a practical test with the high level of 
repeatability. The performance test specifies a severe steering regime 
that would produce oversteer loss of control in nearly every vehicle 
without a modern ESC system, and it specifies a maximum time for the 
vehicle to cease its yaw motion after the steering returns to straight 
ahead.
    At this time, we cannot propose a similar test of the intensity of 
the ESC system's understeer intervention. Typically, systems on 
vehicles with high centers of gravity do not perform understeer 
intervention on dry surfaces because that could increase the 
possibility of an on-road untripped rollover. In such case, attempting 
to maintain the driver's desired path would increase lateral 
acceleration and roll moment. In fact, roll stability control works by 
inducing high levels of understeer when required to prevent tip-up. 
Therefore, tests of understeer intervention must be performed on low 
coefficient surfaces to avoid prohibiting roll stability control 
systems. Unfortunately, the regular methods of producing wet, slippery, 
or icy conditions at automotive proving grounds are useful only for 
such purposes as back-to-back comparisons of vehicles because 
repeatable friction conditions cannot be maintained or precisely 
reproduced. A practical test of understeer intervention is a topic of 
ongoing research.

B. Performance Test of ESC Oversteer Intervention and Stability 
Criteria

Selection of Maneuver
    NHTSA performed research to define a practical, repeatable and 
realistic maneuver test of ESC oversteer intervention. We also made use 
of the results of testing performed by the Alliance on some candidate 
maneuvers to supplement the agency's information. NHTSA's detailed 
research report \17\ has been placed in the docket, and this section 
represents a summary of its major points.
---------------------------------------------------------------------------

    \17\ Forkenbrock, G. et al. (2005) Development of Criteria for 
Electronic Stability Control Performance Evaluation, DOT HS 809 974.
---------------------------------------------------------------------------

    The desired test should discriminate strongly between vehicles with 
and without ESC. Vehicles with ESC disabled were used as non-ESC 
vehicles in the research. It must also facilitate the evaluation of 
both the lateral stability of the vehicle (prevention of spinout) and 
its responsiveness in avoiding obstacles on the road, since stability 
can be gained at the expense of responsiveness. The research program 
consisted of two phases:
    Phase 1: The evaluation of many maneuvers capable of quantifying 
the performance of ESC oversteer intervention using a small sample of 
diverse test vehicles.
    Phase 2: Evaluation of many vehicles using a reduced suite of 
candidate maneuvers.
    Phase 1 testing occurred during the period of April through October 
2004. In this effort, twelve maneuvers were evaluated using five test 
vehicles. Maneuvers utilized automated and driver-based steering 
inputs. If driver-based steering was required, multiple drivers were 
used to assess input variability. To quantify the effects of ESC, each 
vehicle was evaluated with ESC enabled and disabled. Dry and wet 
surfaces were utilized; however, the wet surfaces introduced an 
undesirable combination of test variability and sensor malfunctions. 
Table 5 summarizes the Phase 1 test matrix. Additional details 
pertaining to Phase 1, including more detailed maneuver descriptions 
and details pertaining to test conduct, have been previously 
documented.\18\
---------------------------------------------------------------------------

    \18\ Forkenbrock et al (2005) NHTSA's Light Vehicle Handling and 
ESC Effectiveness Research Program, 19th International Technical 
Conference on the Enhanced Safety of Vehicles (ESV), Washington, DC.

[[Page 54724]]



      Table 5.--NHTSA's 2004 Light Vehicle Handling/ESC Test Matrix
------------------------------------------------------------------------
          Test group 1               Test group 2        Test group 3
------------------------------------------------------------------------
 Slowly Increasing Steer  ..................   Closing
                                                       Radius Turn.
 NHTSA J-Turn (Dry, Wet)   Modified    Pulse
                                   ISO 3888-22.        Steer (500 deg/s,
                                                       700 deg/s).
 NHTSA Fishhook (Dry,      Constant    Sine
 Wet).                             Radius Turn.        Steer (0.5 Hz,
                                                       0.6 Hz, 0.7 Hz,
                                                       0.8 Hz).
                                                      
                                                       Increasing
                                                       Amplitude Sine
                                                       Steer (0.5 Hz,
                                                       0.6 Hz, 0.7 Hz.
                                                       Sine with
                                                       Dwell (0.5 Hz,
                                                       0.7 Hz).
                                                       Yaw
                                                       Acceleration
                                                       Steering Reversal
                                                       (YASR) (500 deg/
                                                       s, 720 deg/s).
                                                      
                                                       Increasing
                                                       Amplitude YASR
                                                       (500 deg/s, 720
                                                       deg/s).
------------------------------------------------------------------------

    To determine whether a particular test maneuver was capable of 
providing a good assessment of ESC performance, NHTSA considered the 
extent to which it possessed three attributes:
    1. A high level of severity that would exercise the oversteer 
intervention of every vehicle's ESC system.
    2. A high level of repeatability and reproducibility.
    3. The ability to assess both lateral stability and responsiveness.
    Phase 2 testing examined the four maneuvers that were considered 
most promising from Phase 1: (1) Sine with Dwell; (2) Increasing 
Amplitude Sine Steer; (3)Yaw Acceleration Steering Reversal (YASR); and 
(4) YASR with Pause.\19\ The two yaw acceleration steering reversal 
maneuvers were designed to overcome the possibility that fixed-
frequency steering maneuvers would discriminate on the basis of vehicle 
properties other than ESC performance, such as wheelbase length. They 
were more complex than the other maneuvers, requiring the automated 
steering machines to trigger on yaw acceleration peaks. However, Phase 
2 research revealed an absence of effects of yaw natural frequency. 
Therefore, the YASR maneuvers were dropped from further consideration 
because their increased complexity was not warranted in light of 
equally effective but simpler alternatives, and their details will not 
be discussed in this summary of NHTSA research. Additional detail on 
the remaining maneuvers is presented below:
---------------------------------------------------------------------------

    \19\ Ibid.

---------------------------------------------------------------------------
Sine With Dwell

    As shown in Figure 2, the Sine with Dwell maneuver was based on a 
single cycle of sinusoidal steering input. Although the peak magnitudes 
of the first and second half-cycles were identical, the Sine with Dwell 
maneuver included a 500 ms pause after completion of the third quarter-
cycle of the sinusoid. In Phase 1, frequencies of 0.5 and 0.7 Hz were 
used. In Phase 2, only 0.7 Hz Sine with Dwell maneuvers were performed. 
As described in NHTSA's report,\20\ the 0.7 Hz frequency was found to 
be consistently more severe than its 0.5 Hz counterpart (in the context 
of this research, severity was quantified by the amount of steering 
wheel angle required to produce a spinout). In Phase 1, the 0.7 Hz Sine 
with Dwell was able to produce spinouts with lower steering wheel 
angles for four of the five vehicles evaluated, albeit by a small 
margin (no more than 20 degrees of steering wheel angle for any 
vehicle).
---------------------------------------------------------------------------

    \20\ Forkenbrock, G. et al. (2005) Development of Criteria for 
Electronic Stability Control Performance Evaluation, Dot HS 809 974.
---------------------------------------------------------------------------

    In a presentation \21\ given to NHTSA on December 3, 2004, the 
Alliance also reported that the 0.5 Hz Sine with Dwell did not 
correlate as well with the responsiveness versus controllability 
ratings made by its professional test drivers in a subjective 
evaluation (the same vehicles evaluated with the Sine with Dwell 
maneuvers were also driven by the test drivers), and it provided less 
input energy than the 0.7 Hz Sine with Dwell.
---------------------------------------------------------------------------

    \21\ Docketed at NHTSA-2004-19951, item 1.
---------------------------------------------------------------------------

Increasing Amplitude Sine

    As shown in Figure 3, the Increasing Amplitude Sine maneuver was 
also based on a single cycle of sinusoidal steering input. However, the 
amplitude of the second half-cycle was 1.3 times greater than the first 
half-cycle for this maneuver. In Phase 1, frequencies of 0.5, 0.6, and 
0.7 Hz were used for the first half cycle; the duration of the second 
half cycle was 1.3 times that of the first.
    The Phase 1 vehicles were generally indifferent to the frequency 
associated with the Increasing Amplitude Sine maneuver. Given our 
desire to reduce the test matrix down from three maneuvers based on 
three frequencies to one, NHTSA selected just the 0.7 Hz frequency 
Increasing Amplitude Sine for use in Phase 2. In the previously 
mentioned presentation given to NHTSA on December 3, 2004, the Alliance 
also reported that the 0.6 Hz Increasing Amplitude Sine did not induce 
vehicle responses significantly different than the 0.5 and 0.7 Hz 
Increasing Amplitude Sine maneuvers.
    To select the best overall maneuver from those used in Phase 2, 
NHTSA considered three attributes: (1) Maneuver severity, (2) face 
validity, and (2) performability. Of the two sinusoidal maneuvers used 
in Phase 2, we determined that the Sine with Dwell was the best 
candidate for evaluating the lateral stability component of ESC 
effectiveness because of its relatively greater severity. Specifically, 
it required a smaller steering angle to produce spinouts (for test 
vehicles with ESC disabled). Also, the Increasing Amplitude Sine 
maneuver produced the lowest yaw rate peak magnitudes in proportion to 
the amount of steering, implying the maneuver was the least severe for 
most vehicles evaluated by NHTSA in Phase 2.
    The performability of the Sine with Dwell and Increasing Amplitude 
Sine maneuvers is excellent. The maneuvers are very easy to program 
into the steering machine, and their lack of rate or acceleration 
feedback loops simplifies the instrumentation required to perform the 
tests. As mentioned previously, Phase 2 testing revealed that the extra 
complexity of YASR maneuvers was unnecessary because the tests were not 
affected by yaw natural frequency differences between vehicles.
    All Phase 2 maneuvers (including the YASR maneuvers) possess an 
inherently high face validity because they are each comprised of 
steering inputs similar to those capable of being produced by a human 
driver in an emergency obstacle avoidance maneuver. However, the 
Increasing Amplitude Sine maneuver may possess the best face validity. 
Conceptually, the steering profile of this maneuver is the most similar 
to that expected to be used by real drivers, and even with steering 
wheel angles as large

[[Page 54725]]

as 300 degrees, the maneuver's maximum effective steering rate is a 
very reasonable 650 deg/sec.
    In light of the above, NHTSA is proposing to use the Sine with 
Dwell maneuver to evaluate the performance of light vehicle ESC systems 
in preventing spinout (oversteer loss of control). On the balance we 
believe that it offers excellent face validity and performability, and 
its greater severity makes it a more rigorous test while maintaining 
steering rates within the capabilities of human drivers.
Spinout Criteria
    The foregoing maneuver selection process required a definition of 
``spinout.'' Spinout can be best explained in the context of the Sine 
with Dwell maneuver. Figure 4 shows the steering wheel angle driven by 
a robotic steering machine during three runs of the maneuver at 
increasing steering amplitudes and the resulting measurements of the 
yaw rate of an actual vehicle being tested. The maneuver is the same as 
that shown in Figure 2, except that the first steering is to the left 
in Figure 4 while it is to the right in Figure 2.
    The test protocol requires the test to be performed at an entrance 
speed of 50 mph (coasting) in both directions at increasing steering 
amplitudes up to a preset maximum or to the point at which the vehicle 
spins out (failing the test). The preset maximum steering angle is the 
larger of either 270 degrees or an angle equal to 6.5 times the 
steering angle that produces 0.3g steady state lateral acceleration for 
the particular test vehicle. This specification of maximum test 
steering angle takes into account differences in steering gear ratio, 
wheelbase, and other factors between vehicles, but provides for testing 
to a steering wheel angle of at least 270 degrees. This maximum 
steering wheel angle is not achieved in the event that the test is 
terminated by spinout at a lower steering wheel angle.
    As shown in Figure 4, in the first run, the steering wheel is 
turned 80 degrees to the left, then 80 degrees to the right following a 
smooth 0.7 Hz sinusoidal pattern. It is held steady for a dwell time of 
0.5 second at 80 degrees right, and then returned to zero (straight 
ahead) also following a sinusoidal pattern. After a short lag, the 
vehicle begins to yaw counter-clockwise in response to the left 
steering. The absolute value of the yaw velocity increases with the 
absolute value of the steering angle, and then the vehicle changes to 
clockwise yaw velocity in response to right steering. At two seconds 
after the beginning of steering, the steering wheel has been turned 
back to straight ahead, and the yaw rate returns to zero after a 
fraction of a second response time. At that point, the vehicle is being 
steered straight ahead, and it is going straight ahead without any yaw 
rotation. The vehicle is responding closely to the steering input, and 
the driver is in control.
    When the steering amplitude is increased to 120 degrees in the next 
run, the vehicle achieves greater yaw velocity because it is following 
a tighter path at the same speed, but it exhibits the same good 
response to steering and remains in control.
    However, when the steering amplitude is increased to 169 degrees, 
the vehicle spins out, exhibiting oversteer loss of control. This 
condition is identified in the yaw rate trace. When the steering is 
straight ahead at time = 2 seconds, the yaw rate for this run is still 
about 35 deg/sec. However, there is a time lag past the instant of 
steering to straight ahead even for the previous runs where there was 
no loss of control. What is different is that the yaw rate does not 
swiftly decline to zero as it does with a vehicle under control. At 
time = 3 seconds, the yaw rate is still the same, and it has actually 
increased at time = 4 seconds in this example. The physical 
interpretation of this graph is that the driver has turned the wheels 
straight ahead and wants the vehicle to go straight, but the vehicle is 
spinning clockwise about a vertical axis through its center of gravity. 
It is out of control in a spinout. The driver's steering input is not 
causing the vehicle to take the desired path and heading, and the 
vehicle would depart the road surface sideways or even backward.
    Figure 4 illustrates that the Sine with Dwell Maneuver is very 
severe. It induced a dramatic spinout in this test vehicle with only 
169 degrees of steering to one direction followed by 169 degrees to the 
other. It is possible that steering angles below 169 degrees but above 
120 degrees would also have caused spinout. Since the test is 
predicated on steering angles up to (or possibly exceeding) 270 
degrees, it would cause spinout in vehicles with far greater lateral 
stability than this test vehicle.
    Figure 5 shows another series of tests of the same vehicle but with 
ESC enabled. The first two runs were at 80 and 120 degrees of steering 
angle, and the vehicle's yaw rate declined to zero in a fraction of a 
second after the steering command. This is the same good response to 
steering exhibited by the vehicle with ESC disabled in the previous 
figure. The third run was conducted at 180 degrees of steering angle. 
This is greater than the 169 degrees that caused a severe loss of 
control without ESC, but the yaw rate returned to zero with the 
steering angle just as quickly as in the runs with less steering.
    The final set of curves in Figure 5 represent a run conducted with 
279 degrees of steering angle. This would be the left-right portion of 
the performance test proposed for the ESC system of this vehicle since 
279 degrees is 6.5 times the steering angle that produces 0.3g steady 
state lateral acceleration for this example vehicle. In this case, the 
yaw rate did not return to zero nearly instantaneously as it had at 
lower steering angle. Instead, it steadily declined after the steering 
was turned to straight ahead, and the vehicle was completely stable and 
going straight in about 1.75 seconds. Clearly, the vehicle remained in 
control compared to its behavior without ESC (see Figure 4) in which 
turning the steering to straight ahead had no effect on the vehicle's 
heading. However, the ESC system required some time to cause the 
vehicle to stop turning in response to the driver's straight ahead 
steering command because the preceding maneuver was so destabilizing. 
The time it takes for the vehicle to stop rotating after it is steered 
straight ahead in this maneuver is a measure of the aggressiveness of 
the ESC oversteer intervention. Some of the early ESC systems were 
tuned to be less aggressive than the example vehicle, and the lag time 
for the vehicle to ``recover'' from the Sine with Dwell Maneuver would 
be longer.
    The first goal of an ESC system is to prevent spinout, but there is 
no hard quantitative definition of spinout. Obviously, the example in 
Figure 4 shows spinout. The vehicle turned nearly front to rear in four 
seconds with the steering wheel straight ahead. In the example of 
Figure 5, the vehicle always responded to steering, but some response 
time was required for it to fully stabilize. In seeking to define 
``spinout'', the agency believes that the question is: How long must 
the response time be before the result would be considered a spinout in 
the severe test maneuver?
    NHTSA used an empirical definition of spinout based on observations 
from vehicle maneuver testing as a rule of thumb. This empirically-
based criterion stipulates that in a symmetric steer maneuver, in which 
the amount of right and left steering is equal, if the final heading 
angle is more than 90 degrees from the initial heading, the vehicle has 
spun out. If a symmetric steer maneuver is performed at a very low 
speed that

[[Page 54726]]

eliminates tire slippage, the heading does not change at all. However, 
a change of heading of about 20 degrees would occur even at low speed 
in the Sine with Dwell Maneuver because of the asymmetric dwell 
portion, making this empirical criterion more conservative. NHTSA's 
research report \22\ contains a statistical study on how quickly an ESC 
system would have to respond to prevent a heading change of more than 
90 degrees during the Sine with Dwell Maneuver at 50 mph with full 
steering using data from all 40 vehicles tested by NHTSA and the 
Alliance.
---------------------------------------------------------------------------

    \22\ Forkenbrock, g. et al. (2005) Development of Criteria for 
Electronic Stability Control Performance Evaluation, DOT HS 809 974
---------------------------------------------------------------------------

    Two measures of response time were considered: (1) The remaining 
yaw rate (as a percent of peak) one second after the steering wheel was 
turned straight ahead, and (2) the remaining percent of peak yaw rate 
after 1.75 seconds. The peak yaw rate is the highest yaw rate during 
the second part of the maneuver. In the example of Figure 5 (test run 
with 279 degrees steering wheel angle) the steering returned to 
straight ahead at 2 seconds. At 3 seconds (one second later), the 
remaining yaw rate was about 30 percent of the peak value achieved at 
about 1.2 seconds. At 3.75 seconds (1.75 seconds after zero steer), the 
remaining yaw rate is zero percent. Statistical analyses performed by 
NHTSA predict that, if the remaining yaw rate at one second after zero 
steer was no more than 35 percent, there is a 95 percent (or greater) 
probability that the heading change will not exceed 90 degrees (no 
spinout by the empirical criterion). For the 1.75 second time interval, 
a remaining yaw rate of no more than 20 percent leads to the same 
prediction.
    The heading change criterion and its statistical interpretation 
provide a context in which to view the yaw rate data in the Sine with 
Dwell tests conducted by NHTSA and by the Alliance on a large sample of 
62 vehicles in production in 2005. Figure 6 illustrates the yaw rate 
response (as a percent of the second yaw rate peak) versus time after 
completion of steer (COS) input, for the 0.7 Hz Sine with Dwell 
maneuver (left to right steering) for all vehicles tested by NHTSA and 
the Alliance. The data represents the most severe yaw rate response 
produced for each vehicle during a particular test series. The form of 
the graph corresponds to the yaw rate curve (for the 169 degree test) 
shown in Figure 4, except that the yaw rate has been normalized and the 
time axis has been shifted by 2.0 seconds so as to focus on the yaw 
rate response after COS. The cluster of curves at the top of Figure 6 
represents the yaw rate response for vehicles with the ESC totally 
disabled, and the cluster at the bottom are for vehicles with the ESC 
fully enabled. Figure 7 shows data from the same vehicles but in a test 
conducted with right-left steering rather than left-right as in Figure 
6.
    Figures 6 and 7 also show the proposed criteria for maximum yaw 
rate at 1.0 second and 1.75 seconds after completion of steering. All 
of the 62 current production vehicles tested met or exceeded the 
proposed criteria with ESC enabled when tested in the left-right 
sequence as shown in Figure 6. However, one of the vehicles did not 
meet the criteria when tested in the right-left sequence as shown in 
Figure 7. Nevertheless, we believe the proposed criteria reasonably 
represent the minimum performance of the oversteer intervention for 
present vehicles with ESC, and that the vehicle representing the single 
exception to the rule can be tuned to operate as well in the right-left 
steering as it did in the left-right test. NHTSA also tested a number 
of the older vehicles whose crash data were used to evaluate the 
effectiveness of ESC in crash reduction. We believe that over 85 
percent of these vehicles have ESC systems that would pass the proposed 
criteria. Therefore, the following proposed performance criteria for 
the Sine with Dwell Maneuver test of ESC oversteer intervention is 
associated with the high level of crash prevention benefits we expect 
and is also typical of the minimum performance of the present fleet of 
ESC vehicles:
[GRAPHIC] [TIFF OMITTED] TP18SE06.000

In both criteria,
[GRAPHIC] [TIFF OMITTED] TP18SE06.001

C. Responsiveness Criteria

    NHTSA's track tests demonstrate dramatic improvements in yaw 
stability provided by ESC. However, NHTSA believes these improvements 
should not come at the expense of poor lateral displacement response to 
the driver's steering inputs. An extreme example of this potential lack 
of responsiveness would occur if an ESC system locked both front wheels 
as the driver begins an abrupt obstacle avoidance maneuver. Assuming 
the road is reasonably level, and the surface friction is uniform, it 
is very likely the wheel lock would suppress any tendency for the 
vehicle to spin out or tip up. However, having the wheels lock would 
also prevent the

[[Page 54727]]

vehicle from responding to the driver's steering inputs. This would 
cause the vehicle to plow straight ahead and collide with the obstacle 
the driver was trying to avoid. Clearly this is not a desirable 
compromise.
    To ensure an acceptable balance between lateral stability and the 
ability for the vehicle to respond to the driver's inputs, NHTSA 
believes a ``responsiveness'' criterion must supplement the agency's 
lateral stability criteria. We propose to use the same series of tests 
with the Sine with Dwell maneuver to characterize both the 
aggressiveness of the oversteer intervention and the lateral 
responsiveness of the vehicle. This maneuver is severe enough to 
exercise the ESC system on any vehicle and test its oversteer 
intervention, and it is possible to measure other metrics during the 
Sine with Dwell maneuver to characterize the vehicle's responsiveness 
as well.
    NHTSA considered a number of metrics to describe the ability of the 
vehicle to react to the steering input, especially in the direction of 
the first half sine of the steering pattern that would relate most 
directly to obstacle avoidance. These metrics involved the lateral 
movement of the vehicle, the lateral speed of the vehicle, the lateral 
acceleration of the vehicle and lag times and distances between 
steering inputs and the various types of responses.
    The lateral movement of the vehicle has the most obvious and direct 
bearing on obstacle avoidance. However, the measurement of lateral 
movement appeared to introduce an undesirable degree of difficulty. 
NHTSA has been measuring the path of vehicles during the development of 
various rollover and handling test maneuvers using a differentially 
corrected Global Positioning System (GPS) method. This method is 
capable of measuring the lateral movement of the vehicle at its center 
of gravity (a good way to compare vehicles of different sizes), but it 
requires costly instruments both on the track and in the vehicle and 
complex procedures. Instruments imbedded in the track would seem to be 
a possible alternative, but they are also problematic. It is difficult 
to place each test vehicle over the instrumented section of roadway 
during the exact same position in the Sine with Dwell steering pattern, 
and it is difficult to determine the lateral movement of the center of 
gravity from roadway sensors when the vehicles approach at various side 
slip angles.
    However, during a briefing \23\ on September 7, 2005, the Alliance 
presented a technique that would greatly simplify the measurement of 
NHTSA's preferred responsiveness metric--lateral displacement in the 
direction of the first steering of the Sine with Dwell maneuver. It 
involves mathematical integration of the onboard lateral acceleration 
measurement at the vehicle center of gravity to obtain lateral 
velocity, and then a second integration of lateral velocity to obtain 
lateral displacement. Double integration of acceleration to calculate 
displacement is not used as a general measurement technique because 
small errors in zero levels of acceleration and speed can produce large 
errors in displacement over time. However, the idea presented by the 
Alliance required double integration for only about one second, and the 
resulting displacement calculations were in good agreement with the GPS 
measurements for vehicles tested by NHTSA.
---------------------------------------------------------------------------

    \23\ Docketed at NHTSA-2004-19951, item 21.
---------------------------------------------------------------------------

    Figure 8 shows the typical lateral displacement as a function of 
time for a vehicle performing the Sine with Dwell maneuver successfully 
(without spinning out). Since the longitudinal travel is roughly 
proportional to time, the bottom trace resembles the path of the 
vehicle with the lateral travel exaggerated. Assuming the wheel is 
first turned to the left, the figure shows that the maximum movement of 
the vehicle to the left lags the maximum left steering angle by almost 
two seconds in this example. Because this maneuver includes a very fast 
steering reversal, the steering wheel has been turned sharply to the 
right before the vehicle has achieved its maximum reaction to the 
initial left steering.
    We propose to use the lateral displacement at 1.07 seconds after 
initiation of steering in the Sine with Dwell maneuver as the 
responsiveness metric rather than the maximum lateral displacement for 
the following reasons. The maximum lateral displacement occurs later in 
the maneuver and occurs at different times for different vehicles. 
Therefore, it is subject to greater potential error from the double 
integration technique, and the errors could systematically affect some 
types of vehicles more than others.
    More importantly, since the interpretation of the metric is the 
obstacle avoidance capability of the vehicle, it makes the most sense 
to measure the lateral displacement of every vehicle the same distance 
from the initiation of steering. This is equivalent to placing the same 
size obstruction at the same place on the roadway for every vehicle. 
Since steering is initiated at 50 mph for all tests, and not much speed 
is scrubbed off in the first second (except for a few systems that 
start automatic braking very early in the maneuver), lateral 
displacement at a set time is roughly equivalent to lateral 
displacement at a set distance. Certainly, the difference in distance 
traveled among test vehicles is much less at 1.07 seconds into the 
maneuver than at the point of maximum lateral displacement.
    A set time of 1.07 seconds is desirable because it coincides with 
an easily recognized discontinuity in the steering trace (the dwell 
period); it is short enough to assure accuracy of the double 
integration technique, and it is long enough to include a high percent 
of the maximum lateral displacement. It is also important to note that 
differences between vehicles in the lateral displacement metric at 1.07 
seconds correlated well with the subjective evaluations of vehicle 
responsiveness provided by expert drivers from several vehicle 
manufacturers.
    The choice of the criterion for this metric was based on the 
responsiveness of the present fleet of cars and light trucks, 
represented by a group of 61 vehicles in 107 vehicle configurations 
(ESC on or ESC off). The group ranged from high-performance sports cars 
to a 15-passenger van with ESC and several long wheelbase diesel pickup 
trucks with GVWRs near 4,536 Kg (10,000 lb) and no ESC. Figure 9 shows 
the range of responsiveness for this fleet, characterized by the 
proposed metric. The least responsive vehicles were not the 15-
passenger van or large pickup trucks, but rather SUVs with roll 
stability control. The highest criterion that can be used without 
prohibiting these implementations of roll stability control is a 
minimum lateral displacement of 1.83 m (half a 12-foot lane width), 
1.07 seconds after initiation of steering in the Sine with Dwell 
maneuver conducted with steering angles of 180 degrees or greater. 
Therefore, we are proposing the test criterion for minimum vehicle 
responsiveness described above because it is practical for all types of 
light vehicles including 15-passenger vans, long wheelbase diesel 
pickups and SUVs with roll stability control. All of the test vehicles 
would satisfy this criterion, including nine SUVs with a roll stability 
control function. However, we expect that manufacturers would make some 
software alterations to the roll stability control programs of a few 
SUVs to gain a greater margin of compliance.

[[Page 54728]]

D. Other Issues

1. ESC Off Switches
    Many vehicles are equipped with ESC systems featuring driver-
selectable modes. These modes are generally subdivided into two groups: 
(1) Systems in which the driver has the ability to fully disable the 
ESC (i.e., throttle and brake intervention are both eliminated), and 
(2) those in which the ESC may only be partially disabled. If the 
option to fully disable the ESC exists, the manner in which it is 
accomplished depends largely on the vehicle's make and model. For some 
vehicles, disabling the ESC is accomplished by momentarily pushing an 
on/off button typically located on the instrument panel, center 
console, or dashboard. Other vehicles require the driver to push the 
ESC on/off button for approximately three to five seconds before the 
ESC can be fully disabled.
    Regardless of which method the vehicle manufacturer has selected, 
the action to manually disable ESC requires a conscious effort by the 
driver. The default setting of every ESC system known to NHTSA is 
``ESC-enabled.'' In other words, at the beginning of each ignition 
cycle, the ESC is always fully enabled regardless of what mode the 
driver had been operating the vehicle in during the previous ignition 
cycle.
    Although many contemporary vehicles are equipped with ESC on/off 
switches, simply pushing the ESC on/off button does not necessarily 
give the driver the ability to fully disable the vehicle's ESC. For 
some vehicles, when the drivers select ``ESC off,'' they are actually 
diminishing, but not fully removing, the aggressiveness of their 
vehicles' ESC intervention.
    Although the crash and test track data clearly demonstrate the 
profound safety benefits of ESC, there are special circumstances in 
which drivers may wish to partially or fully disable their vehicles' 
ESC. Examples of such situations may include:
     Attempting to ``rock'' a vehicle stuck in a deformable 
surface such as snow or mud
     Attempting to initiate movement on deep snow or ice 
(especially if the vehicle is equipped with snow chains)
     Driving through a deep, deformable surface such as mud or 
sand
     Driving with a compact spare tire, tires of mismatched 
sizes or tires with chains.
    To understand how ESC may hinder a driver's ability to operate his 
vehicle in these special conditions, it is important to recall the 
primary ways in which ESC attempts to improve stability: (1) Removal or 
augmentation of drive torque, and (2) brake intervention. In each of 
the examples provided above, the vehicle may require significant 
longitudinal wheel slip in order to initiate or maintain forward 
progress. If ESC remains fully enabled, it will endeavor to reduce what 
it perceives as excessive wheel slip via throttle and/or brake 
intervention. By reducing wheel slip, the vehicle's lateral stability 
is improved; however, this may also inhibit forward progress to the 
point that the vehicle may become (or remain) stuck. Not only can this 
be frustrating for the driver (i.e., the vehicle is not responding to 
their commands), but it may also introduce a potential safety problem 
(e.g., the vehicle slows to a near stop while attempting to be driven 
through a busy intersection).
    Another reason a driver may wish to disable ESC has less to do with 
mobility, and more to do with driving enjoyment. NHTSA acknowledges 
there is a driver demographic that considers the automobile more than 
just a means of transportation. These drivers enjoy participation in 
activities such as motorsports competition and high-performance driving 
schools. In these situations, it is quite possible the driver may not 
wish to realize the improved lateral stability offered by a fully 
enabled ESC, because the intervention providing improved lateral 
stability is achieved by removing the driver's throttle inputs and 
applying the brakes. In a controlled environment, such as the confines 
of a racetrack, this can be frustrating for the driver because ESC 
intervention will have the effect of slowing the vehicle and contradict 
the driver's desire to achieve the lowest possible lap times. In other 
words, aggressive intervention intended to improve safety on the public 
roads may not be appropriate at a racetrack.
    To accommodate these special situations, NHTSA believes vehicle 
manufacturers should be allowed the freedom to install ESC on/off 
switches on all vehicles. Furthermore, the agency is hopeful that this 
provision will have a positive effect on ESC design philosophy. For 
every ESC system presently in production, there exists a balance 
between lateral stability and intervention magnitude. Generally 
speaking, an ESC tuned to optimize lateral stability will require 
intrusive interventions. Conversely, a vehicle equipped with an ESC 
designed with transparent intervention which is not noticeable to the 
driver (often associated with ``sport'' modes), will tend to exhibit 
lower lateral stability. By giving vehicle manufacturers the freedom to 
install ESC on/off switches, both intervention strategies can be 
accommodated, with the more aggressive safety-biased tuning set as the 
system default. The more sport-oriented, transparent interventions 
could then be accessed via the same switch capable of fully disabling 
the ESC. This provision should satisfy the demand for safe, versatile, 
and enjoyable vehicles.
    Vehicle and ESC manufacturers have expressed concern that if ESC 
on/off switches were to be prohibited, there would exist a risk that 
some drivers will fully disable their vehicle's ESC by other means, 
such as disconnecting or removing sensors required by the ESC. By 
opting to disable ESC in this manner, drivers might unknowingly disable 
other important safety features such as the vehicle's antilock brakes. 
In some cases, the vehicle's electronic brake proportioning may also be 
adversely affected, thereby resulting in a significant reduction of the 
vehicle's braking capability. Recognizing the diverse operating 
conditions their vehicles may encounter, many vehicle manufacturers 
presently equip their vehicles with ESC on/off switches.
    In light of the above, we are proposing to permit installation of 
ESC Off switches as a manufacturer option. However, in order to 
preserve the safety benefits presently associated with ESC, NHTSA is 
proposing to require a vehicle equipped with an ESC on/off switch to 
satisfy three important criteria:
    1. The vehicle's ESC must always be fully enabled at the initiation 
of each new ignition cycle, regardless of what mode the driver had 
previously specified.
    2. When evaluated with its ESC fully enabled, the vehicle 
performance must be in compliance with the minimum ESC oversteer 
intervention and responsiveness test criteria.
    3. The vehicle manufacturer must provide a telltale light that 
illuminates to indicate when the vehicle has been put into a mode that 
completely disables ESC or renders it unable to satisfy the ESC 
oversteer intervention test criteria.
    In summary, although there is no way to guarantee drivers will not 
use ESC on/off switches to disable their vehicle's ESC during normal 
driving, potentially negating the significant safety benefits such 
systems offer, NHTSA cannot ignore the fact there are certain operating 
conditions under which on/off switches are advantageous. Furthermore, 
NHTSA anticipates that ESC developers will utilize this design 
flexibility facilitated by the use of ESC on/off switches to maximize 
the ESC effectiveness in its default, fully enabled mode.

[[Page 54729]]

2. ESC Activation and Malfunction Symbols and Telltale
    Most current ESC systems provide an indication to the driver when 
the ESC system is actively intervening to stabilize the vehicle and 
provide a warning to the driver if ESC is unavailable due to a failure 
in the system. When an ESC Off switch is provided, a telltale reminds 
the driver when the ESC has been disabled.
    We believe that there are safety benefits associated with certain 
of these warnings. There is an obvious safety need to warn the driver 
in case of an ESC malfunction so that the system can be repaired. The 
safety need to remind the driver of a driver-selected ESC Off state is 
also obvious because the driver should restore the ESC function as soon 
as possible in order to realize the system's safety benefits. However, 
the safety need for an ESC activation indicator to alert the driver 
during an emergency situation that ESC is intervening is not obvious, 
so the agency undertook research on this point as discussed below.
    NHTSA conducted a study \24\ using the National Advanced Driving 
Simulator (NADS) that included experiments to gain insight into the 
various possibilities regarding ESC activation indicators. The NHTSA 
study involved 200 participants in four age groups and simulated 
driving on wet pavement. It used maneuvers similar to those described 
in Section IV of the Papelis study \25\ also using the NADS. The 
activation indicator experiments used road departures and eye glances 
to the instrument panel as measures of driver performance. The NHTSA 
study compared the performance of drivers given either no indication of 
ESC activation, a steady-burning icon telltale, a flashing icon 
telltale, or an auditory warning. The ESC telltale used in this study 
was the ISO J.14 symbol with the text ``Active'' under it.
---------------------------------------------------------------------------

    \24\ Mazzae, E. et al. (2005) The effectiveness of ESC and 
related Telltales: NADS Wet Pavement Study, DOT HS 809 978.
    \25\ Papelis et al. (2004) Study of ESC Assisted Driver 
Performance Using a Driving Simulator, Report No. N)4-003-PR, 
University of Iowa.
---------------------------------------------------------------------------

    Participants presented with only auditory ESC activation 
indications experienced significantly more road departures (15) than 
participants receiving visual only indications (steady 8, flashing 8) 
or no ESC activation indications (7). This finding was most evident for 
the older driver group who experienced a statistically significant 
increase in road departure events with the auditory ESC indication 
compared to the other three conditions. Younger drivers also showed an 
increased road departure rate with the auditory ESC indication, 
although not at a statistically significant level. These results of the 
road departure study are presented in Table 6.

          Table 6.--Percent Road Departures by ESC Activation Indication and Age Group--ESC Trials Only
----------------------------------------------------------------------------------------------------------------
                                                   All age
                                                    groups       Novice      Younger       Middle       Older
                                                   combined    (percent)    (percent)    (percent)    (percent)
                                                  (percent)
----------------------------------------------------------------------------------------------------------------
None...........................................            7            8            8            6            6
Steady.........................................            8           10            4            6           10
Flashing.......................................            8            9            6            9            8
Auditory.......................................           15            6           14           10           30
----------------------------------------------------------------------------------------------------------------

    Eye glance behavior was examined to determine whether providing 
drivers with an indication of ESC activation would cause them to glance 
at the instrument panel. Results show that participants presented with 
a flashing ESC telltale glanced at the instrument panel significantly 
more frequently (14, statistically significant) during the crash-
imminent event than did participants in the other three ESC conditions. 
Participants presented with a flashing ESC telltale also glanced at the 
instrument panel approximately twice during the crash-imminent event 
versus once for participants in the other three ESC conditions. 
However, average glance duration was approximately twice as long for 
the auditory ESC indication condition than for the other three ESC 
conditions (see Table 7), although this difference was not 
statistically significant.

              Table 7.--Effect of ESC Activation Indication on Eye Glance Behavior--ESC Trials Only
----------------------------------------------------------------------------------------------------------------
                                                   Percent      Number of glances per     Duration of glances(s)
                                                 trials with            trial          -------------------------
                                                 any glance  --------------------------
                                                   to icon         M            SD           M            SD
----------------------------------------------------------------------------------------------------------------
None..........................................          28            1.4          3.9          0.3          0.9
Steady........................................          27            1.1          2.6          0.2          0.1
Flashing......................................          41            2.3          4.7          0.3          0.8
Auditory......................................          27              1          2.6          0.6          1.6
----------------------------------------------------------------------------------------------------------------

    Overall, the significant finding was that the drivers who received 
various ESC activation indicators did not perform better than drivers 
given no indicator. Therefore, there does not appear to be a safety 
need to propose a requirement for an ESC activation indicator as part 
of this rulemaking, and none is proposed. In fact, presentation of an 
auditory indication of ESC activation was shown to increase the 
likelihood of road departure, particularly for older drivers. As a 
result, use of an auditory indication of ESC activation presented 
during the ESC activation is not recommended.
    The flashing indicator was associated with a greater number of 
glances to the instrument panel during the critical driving maneuvers. 
Therefore, flashing would not seem to be a desirable feature, but there 
was no measurable consequence in road departures. The current practice 
for many vehicles is to

[[Page 54730]]

use the same ESC telltale for both activation and malfunction. It 
flashes to indicate activation and stays on continuously in a steady 
burning mode to indicate ESC malfunction. Since NHTSA is proposing to 
not regulate the activation mode, the current practice need not be 
affected.
    The threshold of ESC intervention that would trigger an indication 
of activation is likely to vary with the philosophy of the 
manufacturer. Some manufacturers would also favor displaying the 
activation signal to the driver shortly after the critical driving 
maneuver has ended. This idea may be more intuitively appealing because 
the driver would be warned of slippery road conditions while avoiding 
potential distraction during the critical maneuver. This rulemaking 
does not propose regulation in this area.
    NHTSA believes that the symbol used to identify ESC malfunction 
(and activation if the telltale is shared) should be standardized. This 
is not the case for presently available systems. There are three main 
types of identifiers for ESC activation and malfunction. One type of 
icon shows the rear of a vehicle trailed by a pair of ``S'' shaped skid 
marks. This is the ISO ESC symbol (designated J.14 in ISO standard 
2575). We observed seven variations of this icon in production 
vehicles. The second type is based on a triangle surrounding an 
exclamation mark, which is also used to indicate ABS and traction 
control activation on some vehicles. A variation of this type adds an 
outer counterclockwise semicircular arrow to indicate rotation. The 
third type includes English language phrases and acronyms often 
referring to trade names for specific ESC systems.
    To the extent possible, NHTSA favors symbols over English 
abbreviations to promote harmonization. Also, acronyms for different 
trade names for ESC would only serve to confuse drivers who operate 
different vehicles produced by different manufacturers.
    NHTSA collected data on the recognition of various identifiers 
related to ESC and other vehicle systems by administration of an icon 
comprehension test. A total of 20 members of the general public 
participated in this data collection effort. Gender was balanced. Each 
participant was first presented with an instructional sheet describing 
the procedure for the icon test. The instructions included the 
following statement: ``You are driving down the road and this image 
illuminates on your vehicle's instrument panel * * * ''. Participants 
were then given the test, which consisted of a hand-sized packet 
containing the 20 icons, each on a different page. Each page contained 
two separate questions to ensure that responses were sufficiently 
detailed. The questions were: ``What system or part of the car is the 
light referring to?'' and ``What is the light telling you about that 
part or system?'' A fill-in-the-blank line for participant response 
followed each question.
    Responses for ESC-related symbols were given full credit as correct 
if they contained the words ``stability control'' or ``ESC.'' ESC icon 
responses containing the word ``traction'' were given partial credit. 
Selected results of the comprehension test are presented in Figure 10. 
While few people knew what ``ESC'' meant, the ISO J.14 icon was the 
most successful in communicating to people a message relating to 
traction. The icon consisting of a counterclockwise, circular arrow 
surrounding a triangle containing an exclamation point, while present 
in a number of current vehicles, was not meaningful to any of the 20 
respondents, and there was little recognition of the triangle without 
the arrow.
    Based upon the results of this albeit limited study, the ISO J.14 
symbol appears to be the best choice of the identifiers in use for a 
standard symbol for ESC. As with any symbol, drivers will have to learn 
its precise meaning, but we believe that, to some extent, it correctly 
evokes an association with skidding. Also, the ISO J.14 symbol and 
close variations were the symbols used presently by the greatest number 
of vehicle manufacturers that used an ESC symbol. Therefore, NHTSA is 
proposing the ISO J.14 symbol as the required ESC symbol in FMVSS No. 
126.
3. ESC Off Switch Symbol and Telltale
    There is an obvious safety need to prevent drivers from 
misunderstanding the operation of the ESC Off switch. Drivers usually 
encounter vehicle dashboard switches as a means of turning on vehicle 
functions that are off when the vehicle is started. However, an ESC Off 
switch presents the opposite situation, because full ESC operation is 
the default condition of the vehicle following each ignition cycle. 
Therefore, we believe that the switch must be labeled unambiguously.
    The ISO convention is to draw a slash through a symbol to signify 
negation--the disabling or turning off of a vehicle function. However, 
Table 8, which examines potential symbols to indicate when the ESC 
system is off, shows that this convention applied to the ISO J.14 ESC 
symbol does not create an unambiguous symbol for ESC off.
[GRAPHIC] [TIFF OMITTED] TP18SE06.002

    Once again, the ISO J.14 symbol is desirable because it connoted 
the idea of traction and skidding even to people who had not heard of 
electronic stability control. However, the literal meaning of the 
symbol of a vehicle skidding with a slash through it is the negation of 
skidding, which could be assumed to mean ESC on. The problem with the 
slash symbol is not just that a driver will not understand it and have 
to consult the owner's manual, but that the driver could reasonably 
understand it to have the opposite meaning and believe it is not 
necessary to consult the owner's manual. Therefore, a purely 
pictographic approach to adapting the ESC symbol for the off switch is 
not feasible. NHTSA believes it is necessary to make the identification 
of when ESC is turned off explicit by using the English word ``OFF,'' 
as shown in the right hand box of Table 8.
    The same situation occurs for the telltale indicating what the 
current state of ESC system is. The off switch toggles the ESC system 
between the on and off states. Even someone who understands that the 
ESC Off switch is not required to use ESC normally must be certain of 
the ESC state after he has touched the switch. Therefore, the slash 
symbol cannot be used for the telltale either because it leads to the 
same ambiguity regarding the state of the ESC system

[[Page 54731]]

when the telltale is lighted. Also, even though it is used for 
malfunction indication, the ISO J.14 symbol alone would create 
ambiguity about the on/off state of ESC if it were used with the Off 
switch. Therefore, the symbol with the English word ``OFF'' is also 
proposed for the telltale that will be required for the ESC Off switch.

E. Alternatives to the Agency Proposal

    Section 10301 of the Safe, Accountable, Flexible, Efficient 
Transportation Equity Act: A Legacy for Users of 2005 \26\ (SAFETEA-LU) 
requires that the Secretary ``establish performance criteria to reduce 
the occurrence of rollovers consistent with stability enhancing 
technologies'' and ``issue a proposed rule * * * by October 1, 2006, 
and a final rule by April 1, 2009.'' NHTSA has long been concerned 
about the number of rollover fatalities and injuries, and it has 
pursued a number of actions in the past to reduce rollovers that were 
alternatives to the present proposal.
---------------------------------------------------------------------------

    \26\ Pub. L. 109-59, 119 stat. 1144 (2005).
---------------------------------------------------------------------------

    One of the past alternatives sought to require higher rollover 
resistance for light trucks. NHTSA published an Advance Notice of 
Proposed Rulemaking in 1992 \27\ which explored the idea of setting a 
minimum level of rollover resistance based on the track width and 
height of the center of gravity. These are the primary components of 
``geometric stability'' which can be expressed by metrics such as 
Static Stability Factor (SSF) or Tilt Table Ratio which is a related 
measurement using a ``tilt table'' to measure how far a vehicle on a 
platform could be tilted laterally before tipping over.
---------------------------------------------------------------------------

    \27\ 57 FR 242 (Jan. 3, 1992).
---------------------------------------------------------------------------

    However, the contemplated approach of regulating the geometric 
stability of vehicles did not lead to a mandatory standard. Its effect 
would have been crash mitigation by reducing the number of single-
vehicle crashes that turn into rollovers rather than crash prevention. 
In order to produce life saving benefits, the proposed geometric 
stability level would have had to be placed above that of almost all 
contemporary SUVs, pickup trucks with four-wheel drive, and full size 
vans. A regulation of this type would have made classes of vehicles 
with high ground clearance unavailable to consumers.
    Rather than pursue such a rulemaking, NHTSA chose instead to add 
rollover resistance to the NCAP consumer information program in 2001. 
In this way, persons needing vehicles with high ground clearance (which 
have poorer rollover resistance) could make an informed choice about 
the tradeoffs, but consumers would be encouraged to choose vehicles 
with greater rollover resistance. The NCAP program uses market-based 
incentives to encourage manufacturers to maximize rollover resistance 
within the limitations of the vehicle class. Manufacturers responded to 
these NCAP ratings with improvements in rollover resistance resulting 
from the generally wider track widths of newer SUVs derived from 
passenger car platforms and also improvements where possible in truck-
based SUVs during major redesigns. A recent trend in improving the 
rollover resistance of SUVs has been the addition of roll stability 
control. This feature prevents tip-up in the maneuver test that was 
added to NCAP in the 2004 model year, resulting in a small reduction in 
the predicted rollover rate.
    We believe the NCAP approach has been a successful way to address 
the dilemma of higher rollover resistance being at odds with some of 
the features that draw consumers to light trucks. Despite the recent 
trend of improvement, SUVs cannot match passenger cars in geometric 
stability because taller bodies and higher ground clearance are the 
features that distinguish SUVs from passenger cars. Nevertheless, the 
rollover resistance of SUVs has substantially improved since the 
establishment of NCAP ratings, and consumers are in a better position 
to make vehicle decisions for themselves and for young drivers in their 
family.
    While the use of ESC to prevent single vehicle crashes is a better 
way of reducing rollovers than any countermeasures previously 
available, there are alternatives in terms of how NHTSA could regulate 
ESC systems. The agency considered two alternatives to the proposal. 
The first was to limit the ESC standard's applicability only to LTVs. 
The second alternative was to not require a 4-wheel system, which would 
allow a 2-wheel system to be used by manufacturers.
    The agency considered the first alternative for two reasons: (a) 
The ESC effectiveness rates for LTVs against single-vehicle crashes 
were almost twice as high of the effectiveness rates for passenger cars 
(PCs), and (b) LTVs generally had a higher propensity for rollover than 
PCs. The alternative would address the core rollover issue and target 
the high-risk rollover vehicle population. However, after examining the 
safety impact and the cost-effectiveness of the alternative, the agency 
determined that an excellent opportunity to reduce passenger car 
crashes would be lost if PCs were excluded from the proposal.
    We examined this alternative by looking at the impacts of requiring 
ESC for passenger cars. Requiring ESC for passenger cars would save 956 
lives and reduce 34,902 non-fatal injuries. Following this analysis 
through the cost-effectiveness equations, the cost-effectiveness 
analysis shows that ESC is highly cost-effective for PCs alone. For 
PCs, the cost per equivalent life saved is estimated to be $0.35 
million at a 3 percent discount rate and $0.47 million at a 7 percent 
discount rate. The benefit-cost would be $4.8 billion at a 3 percent 
discount rate and $3.8 billion at a 7 percent discount rate.
    Given the fact that ESC is highly cost-effective and that extending 
the ESC applicability to PCs would save a large number of additional 
lives (956) and reduce a large number of additional injuries (34,902), 
the agency is not proposing this alternative.
    The second alternative considered was to require only that ESC 
operate on the two front wheels. General Motors has utilized a 2-wheel 
ESC system in many of its ESC-equipped passenger cars through MY 2005, 
but it is using 4-wheel ESC systems exclusively in MY 2006. All other 
manufacturers have utilized a 4-wheel ESC system in their vehicles. 
Only 4-wheel systems are capable of both understeer and oversteer 
mitigation.
    Statistical analyses comparing 2-wheel to 4-wheel ESC systems were 
performed.\28\ The effectiveness estimates show a potentially enhanced 
benefit of 4-wheel ESC systems over 2-wheel ESC systems in reducing 
single-vehicle run-off-road crashes (significant at the 0.05 level or 
better), although the benefit could not have been shown in a separate 
analysis of fatal-only crashes likely due to the small sample size.
---------------------------------------------------------------------------

    \28\ Dang, J. (2006) Statistical Analysis of The Effectiveness 
of Electronic Stability Control (ESC) Systems, U.S. Dept. of 
Transportation, Washington, DC (publication pending peer review). A 
draft version of this report, as supplied to peer reviewers, has 
been placed in the docket for this rulemaking.
---------------------------------------------------------------------------

    The agency's contractor performed a teardown study to determine the 
difference in costs between a 2-wheel and 4-wheel system, and it found 
that the 2-wheel system is about $10.00 less expensive. However, it is 
not intuitively obvious that the difference need be this much, and with 
a sample size of one, it is possible that other changes in design may 
be affecting this estimate.
    Since the industry has moved away from the 2-wheel system on its 
own, and it appears that the difference in cost of $10 or less will be 
insignificant compared to the additional benefits

[[Page 54732]]

achieved with 4-wheel ESC, we are not providing a full analysis of this 
alternative at this time.
    Based on the available information, the agency is proposing the 4-
wheel system. The agency's decision is based on our and the industry's 
engineering judgment that the 4-wheel system is more effective, the 
effectiveness study showing that the 4-wheel system is more effective 
than the 2-wheel system in reducing crashes, the industry trend towards 
installing the 4-wheel system in their vehicles, and the minimal cost 
differences between 2-wheel and 4-wheel ESC systems.
    We have also examined the possibility that there may be alternative 
approaches to achieving the benefits of ESC that could involve simpler 
or less costly technology. To answer this question we first identified 
the basic functional requirements of a vehicle control system that 
would maintain vehicle path control in both oversteer and understeer 
situations. The first functional requirement is a means of predicting 
what the driver's intended path, i.e., where the driver wants the 
vehicle to go. The second functional requirement is to be able to 
determine the current actual path of the vehicle, i.e., its current 
dynamic state. The final requirement is to determine how the intended 
and actual paths deviate and then to exercise automatic control to 
minimize or eliminate this deviation. The basic question then is 
whether there exists another fundamentally different technological 
approach to achieving the three key functional requirements identified 
above, than those employed in current ESC systems.
    Functional Requirement No. 1: One may infer the desired path from a 
knowledge of the driver's instantaneous steering, throttle, and braking 
commands as well as the current dynamic state of the vehicle. This 
requires that sensors be installed to determine the values of each of 
these control inputs. Although specific sensor technology and costs may 
vary from one manufacturer to another, there is no known alternative to 
acquiring knowledge of the driver's intent other than through this 
system of vehicle sensors.
    Functional Requirement No. 2: Once the intended path is 
established, the next requirement is determine the vehicle's actual 
path. Here again a range of sensor information is needed to establish 
the vehicle's dynamic state. Among the state variables that must be 
determined, the two most critical are lateral acceleration and yaw 
velocity. Acquiring information of these quantities requires special 
vehicle dynamic sensors. Again, though sensor technology and cost may 
vary, we are not aware of any alternative approach to acquiring this 
essential information.
    Functional Requirement No. 3: With information on the driver's 
desired path and the actual vehicle path, a means of comparing the two 
and eliminating or minimizing deviations is needed. This requires an 
electronic comparator and error generator. A means of altering the 
actual vehicle path so as to bring it into alignment with the desired 
path is the third critical function. The vehicle path can only be 
changed as a result of forces generated between the tire and roadway. 
Drivers intuitively rely on lateral tire forces generated through 
steering inputs to change the vehicle heading and path. Though not 
comprehended by most drivers, the heading (and consequently the path) 
can also be changed by means of unbalanced braking forces, which is the 
approach used by ESC. We do not believe that an approach that would 
assume control of the driver's steering authority as an alternative 
method of correcting the vehicle path would be acceptable to most 
drivers. Also, braking intervention at individual wheels is much more 
likely to produce the necessary yaw torque on slippery surfaces than 
steering intervention, and steering intervention would have limited 
effect on understeer loss-of-control even on surfaces with high levels 
of friction. No manufacturer has proposed this method of intervention 
to correct path deviation in loss of control situations.
    In summary, while specific differences in the implementation may 
exist between ESC systems, the basic elements of the feed-back control 
systems are common to all. We have concluded that to accomplish the 
goal of preventing a vehicle from losing path or directional control a 
vehicle must be equipped with all of the essential components of the 
current ESC systems. There does not appear to be any current 
alternative to the technology that is being mandated that attains the 
goals of this proposed rule. We solicit comment on alternatives to 
mandating the installation of ESC, consistent with our statutory 
directive.

VI. Leadtime

    Considering the very high level of potential life-saving benefits 
of this proposed safety standard, NHTSA wishes to avoid excessive delay 
in its development and implementation. Except for possibly some low-
production-volume vehicles with infrequent design changes, NHTSA 
believes that most other vehicles can reasonably be equipped with ESC 
within three to four model years (MY) from the date of issuance of a 
final rule. This proposal does not require improvements in ESC 
technology over the present 2006 MY systems, and most vehicles would 
likely experience some level of redesign in the next five years in the 
normal course of business. There already is a strong trend to provide 
ESC as standard equipment on SUVs, and it is likely that market segment 
will be equipped with ESC prior to a final rule becoming effective. We 
have taken these considerations into account in proposing both the 
phase-in plan as well as the final compliance date for full 
implementation of the standard.
    Our intention is to have 90 percent of the subject fleet equipped 
with ESC in the 2011 model year that starts September 1, 2010. 
Accordingly, assuming the final rule is published in June 2008, and 
becomes effective September 1, 2008, we are proposing the following 
phase-in schedule:

September 1, 2008--30 percent of fleet.
September 1, 2009--60 percent of fleet.
September 1, 2010--90 percent of fleet.
September 1, 2011--All light vehicles.

    However, NHTSA is proposing to exclude multi-stage manufacturers 
and alterers from the requirements of the phase-in and to extend by one 
year the time for compliance by those manufacturers (i.e., until 
September 1, 2012). This NPRM also proposes to exclude small volume 
manufacturers (i.e., manufacturers producing less than 5,000 vehicles 
for sale in the U.S. market in one year) from the phase-in, instead 
requiring such manufacturers to fully comply with the standard on 
September 1, 2011.
    Under our proposal, vehicle manufacturers would be permitted to 
earn carry-forward credits for compliant vehicles, produced in excess 
of the phase-in requirements, which are manufactured between the 
effective date of the final rule and the conclusion of the phase-in 
period. We note that carry-forward credits would not be permitted to be 
used to defer the mandatory compliance date of September 1, 2011 for 
all covered vehicles.
    The initial phase-in of 30 percent occurring almost simultaneously 
with the effective date is the result of our belief that all 
manufacturers subject to the phase-in already plan to exceed that level 
of ESC installation in the 2009 MY. Confidential information submitted 
to NHTSA by many manufacturers indicate that all responding 
manufacturers will exceed a 30 percent installation rate, and that 
several will exceed it by a large margin that would earn considerable 
carry-forward credits.

[[Page 54733]]

VII. Benefits and Costs

A. Summary

    This section summarizes our analysis of the benefits, costs, and 
cost per equivalent life saved as a result of the proposed ESC 
requirement. As noted previously, the life- and injury-saving potential 
of ESC is very significant, both in absolute terms and when compared to 
prior agency rulemakings. This proposal for ESC, if made final, would 
save 1,536 to 2,211 lives and cause a reduction of 50,594 to 69,630 
MAIS 1-5 injuries annually once all passenger vehicles have ESC. This 
compares favorably with the Regulatory Impact Analyses for other 
important rulemakings such as FMVSS No. 208 mandatory air bags (1,964 
to 3,670 lives saved), FMVSS No. 214 side impact protection (690 to 
1,030 lives saved), and FMVSS No. 201 upper interior head impact 
protection (870 to 1,050 lives saved). The ESC proposal would also save 
$396 to $555 million annually in property damage and travel delay 
(undiscounted). The total cost of the proposal is estimated to be $985 
million.
    The proposal is extremely cost-effective. The cost per equivalent 
life saved would range from $0.19 to $0.32 million at a 3 percent 
discount and $0.27 to $0.43 million at a 7 percent discount. Again, the 
cost-effectiveness for ESC compares favorably with the Regulatory 
Impact Analyses for other important rulemakings such as FMVSS No. 202 
head restraints safety improvement ($2.61 million per life saved), 
FMVSS No. 208 center seat shoulder belts ($3.39 to $5.92 million per 
life saved), FMVSS No. 208 advanced air bags ($1.9 to $9.0 million per 
life saved), and FMVSS No. 301 fuel system integrity upgrade ($1.96 to 
$5.13 million per life saved).
    For a more complete discussion of the benefits and costs associated 
with this proposed rulemaking for ESC, please consult the Preliminary 
Regulatory Impact Analysis (PRIA), which is available in the docket for 
this rulemaking.

B. ESC Benefits

    As discussed in detail in Chapter IV (Benefits) of the PRIA, we 
anticipate that this rulemaking would prevent 70,344 to 95,153 crashes 
(1,408 to 2,355 fatal crashes and 69,936 to 91,798 non-fatal crashes). 
Preventing these crashes entirely is the ideal safety outcome and would 
translate into 1,536 to 2,211 lives saved and 50,594 to 69,630 MAIS 1-5 
injuries prevented.
    The above figures include benefits related to rollover crashes. 
However, in light of the relatively severe nature of crashes involving 
rollover, ESC's contribution toward mitigating the problem associated 
with this subset of crashes should be noted. We anticipate that this 
rulemaking would prevent 37,309 to 41,147 rollover crashes (1,057 to 
1,314 fatal crashes and 36,252 to 39,833 non-fatal crashes). This would 
translate into 1,161 to 1,445 lives saved and 43,901 to 49,010 MAIS 1-5 
injuries prevented in rollovers.
    In addition, preventing crashes would also result in benefits in 
terms of travel delay savings and property damage savings. We estimate 
that this rulemaking would save $396 to $555 million, undiscounted, in 
these two categories ($310 to $348 million of this savings attributable 
to prevented rollover crashes).

C. ESC Costs

    In order to estimate the cost of the additional components required 
to equip every vehicle in future model years with an ESC system, 
assumptions were made about future production volume and the 
relationship between equipment found in anti-lock brake systems (ABS), 
traction control (TC), and ESC systems. We assumed that in an ESC 
system, the equipment of ABS is a prerequisite. Thus, if a passenger 
car did not have ABS, it would require the cost of an ABS system plus 
the additional incremental costs of the ESC system to comply with an 
ESC standard. We assumed that traction control (TC) was not required to 
achieve the safety benefits found with ESC. We estimated a future 
annual production of 17 million light vehicles consisting of nine 
million light trucks and eight million passenger cars.
    An estimate was made of the MY 2011 installation rates of ABS and 
ESC. It served as the baseline against which both costs and benefits 
are measured. Thus, the cost of the standard is the incremental cost of 
going from the estimated MY 2011 installations to 100 percent 
installation of ABS and ESC. The estimated MY 2011 installation rates 
are presented in Table 9.

                Table 9.--MY 2011 Predicted Installations
                  [Percent of the light vehicle fleet]
------------------------------------------------------------------------
                                                    ABS       ABS + ESC
------------------------------------------------------------------------
Passenger Cars................................           86           65
Light Trucks..................................           99           77
------------------------------------------------------------------------

    Based on the assumptions above and the data provided in Table 9, 
Table 10 presents the percent of the MY 2011 fleet that would need 
these specific technologies in order to equip 100 percent of the fleet 
with ESC.

  Table 10.--Percent of the Light Vehicle Fleet Requiring Technology To
                      Achieve 100% ESC Installation
------------------------------------------------------------------------
                                       None      ABS + ESC     ESC only
------------------------------------------------------------------------
Passenger Cars...................           65           14           21
Light Trucks.....................           77            1           22
------------------------------------------------------------------------

    The cost estimates developed for this analysis were taken from tear 
down studies that contractors have performed for NHTSA. This process 
resulted in estimates of the consumer cost of ABS at $368 and the 
incremental cost of ESC at $111. Thus, it would cost a vehicle that 
does not have ABS currently, $479 to meet this proposal. Combining the 
technology needs in Table 10 with the cost above and assumed production 
volumes yields the cost estimate in Table 11 for the proposed standard.

[[Page 54734]]



        Table 11.--Summary of Vehicle Costs for the ESC Proposal
                                 [2005$]
------------------------------------------------------------------------
                                                Average      Total costs
                                             vehicle costs    (million)
------------------------------------------------------------------------
Passenger Cars.............................          $90.3          $728
Light Trucks...............................           29.2           363
                                            ----------------------------
    Total..................................           58             985
------------------------------------------------------------------------

    In summary, Table 11 shows that the new vehicle costs of providing 
electronic stability control and antilock brakes will add approximately 
$985 million to new light vehicles at a cost averaging over $58 per 
vehicle.
    In addition, we note that this proposal would add weight to 
vehicles and consequently would increase their lifetime use of fuel. 
Most of the added weight is for ABS components and very little is for 
the ESC components. Since 99 percent of light trucks are predicted to 
have ABS in MY 2011, the weight increase for light trucks is less than 
one pound and is considered negligible. The average weight gain for 
passenger cars is estimated to be 2.1 pounds, resulting in 2.6 more 
gallons of fuel being used over the lifetime of these vehicles. The 
present discounted value of the added fuel cost over the lifetime of 
the average passenger car is estimated to be $2.73 at a 7 percent 
discount rate and $3.35 at a 3 percent discount rate.
    We have not included in these cost estimates, allowances for ESC 
system maintenance and repair. Although all complex electronic systems 
will experience component failures from time to time necessitating 
repair, our experience to date with existing systems is that their 
failure rate is not outside the norm. Also, there are no routine 
maintenance requirements for ESC systems.

VIII. Public Participation

How Can I Influence NHTSA's Thinking on This Notice?

    In developing this notice, NHTSA tried to address the concerns of 
all stakeholders. Your comments will help us determine what standard 
should be set for ESC as part of FMVSS No. 126. We invite you to 
provide different views about the issues presented, new approaches and 
technologies about which we did not ask, new data, how this notice may 
affect you, or other relevant information. We welcome your views on all 
aspects of this notice. Your comments will be most effective if you 
follow the suggestions below:
     Explain your views and reasoning as clearly as possible.
     Provide empirical evidence, wherever possible, to support 
your views.
     If you estimate potential costs, explain how you arrived 
at that estimate.
     Provide specific examples to illustrate your concerns.
     Offer specific alternatives.
     Reference specific sections of the notice in your 
comments, such as the units or page numbers of the preamble, or the 
regulatory sections.
     Be sure to include the name, date, and docket number of 
the proceeding as part of your comments.

How Do I Prepare and Submit Comments?

    Your comments must be written and in English. To ensure that your 
comments are correctly filed in the Docket, please include the docket 
number of this document in your comments.
    Your comments must not be more than 15 pages long. (49 CFR 553.21). 
We 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.
    Please submit two copies of your comments, including the 
attachments, to Docket Management at the address given above under 
ADDRESSES.
    You may also submit your comments to the docket electronically by 
logging onto the Dockets Management System Web site at http://dms.dot.gov. Click on ``Help & Information'' or ``Help/Info'' to obtain 
instructions for filing your document electronically.

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. Each electronic filer will 
receive electronic confirmation that his or her submission has been 
received.

How Do I Submit Confidential Business Information?

    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, 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 delineating that information, as specified in our confidential 
business information regulation. (49 CFR part 512.)

Will the Agency Consider Late Comments?

    We 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 it in 
developing a final rule (assuming that one is issued), we will consider 
that comment as an informal suggestion for future rulemaking action.

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 review filed public comments on the Internet. To read 
the comments on the Internet, take the following steps:
    1. Go to the Docket Management System (DMS) Web page of the 
Department of Transportation (http://dms.dot.gov/).
    2. On that page, click on ``search.''

[[Page 54735]]

    3. On the next page (http://dms.dot.gov/search/), type in the four-
digit docket number shown at the beginning of this document. (Example: 
If the docket number were ``NHTSA-1998-1234,'' you would type 
``1234.'') After typing the docket number, click on ``search.''
    4. On the next page, which contains docket summary information for 
the docket you selected, click on the desired comments. You may 
download the comments. Although the comments are imaged documents, 
instead of word processing documents, the ``pdf'' versions of the 
documents are word searchable.
    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. Accordingly, 
we recommend that you periodically check the Docket for new material.

Data Quality Act Statement

    Pursuant to the Data Quality Act, in order for substantive data 
submitted by third parties to be relied upon and used by the agency, it 
must also meet the information quality standards set forth in the DOT 
Data Quality Act guidelines. Accordingly, members of the public should 
consult the guidelines in preparing information submissions to the 
agency. DOT's guidelines may be accessed at http://dmses.dot.gov/submit/DataQualityGuidelines.pdf.

IX. Regulatory Analyses and Notices

A. Vehicle Safety Act

    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.\29\ These motor vehicle safety standards set the minimum level 
of performance for a motor vehicle or motor vehicle equipment to be 
considered safe.\30\ When prescribing such standards, the Secretary 
must consider all relevant, available motor vehicle safety 
information.\31\ The Secretary also must consider whether a proposed 
standard is reasonable, practicable, and appropriate for the type of 
motor vehicle 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.\32\ The 
responsibility for promulgation of Federal motor vehicle safety 
standards has been delegated to NHTSA.\33\
---------------------------------------------------------------------------

    \29\ 49 U.S.C. 30111(a).
    \30\ 49 U.S.C. 30102(a)(9).
    \31\ 49 U.S.C. 30111(b).
    \32\ Id.
    \33\ 49 U.S.C. 105 and 322; delegation of authority at 49 CFR 
1.50.
---------------------------------------------------------------------------

    As noted previously, section 10301 of SAFETEA-LU mandated a 
regulation to reduce the occurrence of rollovers ``consistent with 
stability enhancing technologies.'' In developing this proposed rule 
for ESC, the agency carefully considered the statutory requirements of 
both SAFETEA-LU and 49 U.S.C. Chapter 301.
    First, in preparing this document, the agency carefully evaluated 
available research, testing results, and other information related to 
ESC technology. The agency performed extensive research on its own and 
made use of research performed by the Alliance of Automobile 
Manufacturers. We have also performed analyses of ESC using actual 
crash data to determine the effectiveness of ESC in reducing single-
vehicle crashes and rollovers. In sum, this document reflects our 
consideration of all relevant, available motor vehicle safety 
information.
    Second, to ensure that the ESC requirements are practicable, the 
agency research and the Alliance research documented the capabilities 
of current ESC systems and dynamic performance of model year 2005 
vehicles equipped with them. We have tentatively concluded that all 
current production vehicles equipped with ESC systems would comply with 
the equipment requirements, that all but one vehicle would comply with 
the performance tests proposed, and that only minor software tuning 
would be required to bring that vehicle into compliance. In sum, we 
believe that this proposed rule is practicable, in that it could be 
implemented with existing technology and is quite cost effective given 
its potential to prevent thousands of deaths and injuries each year, 
particularly those associated with single-vehicle crashes leading to 
rollover.
    Third, the regulatory text following this preamble is stated in 
objective terms in order to specify precisely what equipment 
constitutes an ESC system, what performance is required and how 
performance would be tested under the standard. The proposed definition 
of an ESC system is based on an industry consensus definition developed 
by the Society of Automotive Engineers (SAE). The proposed rule also 
includes performance requirements and test procedures for the timing 
and intensity of the oversteer intervention of the ESC system and the 
responsiveness of the vehicle. This test procedure involves a precisely 
defined steering pattern performed by a robotic steering machine under 
a defined set of test conditions (e.g., ambient temperature, road test 
surface, vehicle load, vehicle speed). Performance is defined by 
objective measurements of yaw rate and lateral acceleration taken by 
scientific instruments at precise times with reference to the steering 
pattern. The standard's test procedures carefully delineate how testing 
would be conducted. Thus, the agency believes that this test procedure 
is sufficiently objective and would not result in any uncertainty as to 
whether a given vehicle satisfies the requirements of the ESC standard.
    Finally, we believe that this proposed rule is reasonable and 
appropriate for motor vehicles subject to the applicable requirements. 
As discussed elsewhere in this notice, the agency is addressing 
Congress' concern about rollover crashes resulting in fatalities and 
serious injuries. Under section 10301 of SAFETEA-LU, Congress mandated 
installation of stability enhancing technologies in new vehicles to 
reduce rollovers. NHTSA has determined that ESC systems meeting the 
requirements of this proposed rule offer an effective countermeasure to 
rollover crashes and to other single-vehicle and certain multi-vehicle 
crashes. Accordingly, we believe that this proposed rule is appropriate 
for vehicles that would become subject to these provisions because it 
furthers the agency's objective of preventing deaths and serious 
injuries, particularly those associated with rollover crashes.

B. Executive Order 12866 and DOT Regulatory Policies and Procedures

    Executive Order 12866, ``Regulatory Planning and Review'' (58 FR 
51735, October 4, 1993), provides for making determinations whether a 
regulatory action is ``significant'' and therefore subject to Office of 
Management and Budget (OMB) review and to the requirements of the 
Executive Order. The Order defines a ``significant regulatory action'' 
as one that is likely to result in a rule that may:
    (1) Have an annual effect on the economy of $100 million or more or 
adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or State, local, or Tribal governments or 
communities;
    (2) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency;

[[Page 54736]]

    (3) Materially alter the budgetary impact of entitlements, grants, 
user fees, or loan programs or the rights and obligations of recipients 
thereof; or
    (4) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    We have considered the impact of this action under Executive Order 
12866 and the Department of Transportation's regulatory policies and 
procedures. This action has been determined to be economically 
significant under the Executive Order, and it is also a subject of 
congressional interest and a mandate under section 10301 of SAFETEA-LU. 
The agency has prepared and placed in the docket a Preliminary 
Regulatory Impact Analysis. This rulemaking action is also significant 
within the meaning of the Department of Transportation's Regulatory 
Policies and Procedures (44 FR 11034; February 26, 1979). Accordingly, 
this rulemaking document was reviewed by the Office of Management and 
Budget under Executive Order 12866, ``Regulatory Planning and Review.'' 
The agency has estimated that compliance with this proposal would cost 
approximately $985 million per year and have net benefits as high as 
$10.6 billion per year. Thus, this rule would have greater than a $100 
million effect.

C. Regulatory Flexibility Act

    Pursuant to the Regulatory Flexibility Act of 1980 (5 U.S.C. 601 et 
seq., as amended by the Small Business Regulatory Enforcement Fairness 
Act (SBREFA) of 1996), whenever an agency is required to publish a 
notice of rulemaking for any proposed or 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 organizations, and small governmental jurisdictions). 
However, no regulatory or flexibility analysis is required if the head 
of an agency certifies that the rule will not have a significant 
economic impact on a substantial number of small entities. SBREFA 
amended the Regulatory Flexibility Act to require Federal agencies to 
provide a statement of the factual basis for certifying that a rule 
will not have a significant economic impact on a substantial number of 
small entities.
    NHTSA has considered the effects of this rulemaking action under 
the Regulatory Flexibility Act and has included an initial regulatory 
flexibility analysis in the PRE. This analysis discusses potential 
regulatory alternatives that the agency considered that would still 
meet the identified safety need of reducing the occurrence of rollovers 
through stability enhancing technologies. Alternatives considered 
included (a) applying the standard to light trucks but not to passenger 
cars and (b) permitting front-wheel-only ESC systems that are incapable 
of understeer intervention. The first alternative was rejected because 
passenger car ESC systems would save 956 lives and reduce 34,902 
injuries annually at a cost per equivalent fatality that would easily 
justify a separate rule for passenger cars. The second alternative was 
rejected because front-wheel-only ESC systems would prevent 30 percent 
fewer single-vehicle crashes without producing a large cost saving.
    To summarize the conclusions of that analysis, the agency believes 
that the proposal would have a significant economic impact on a 
substantial number of small businesses. There are currently four small 
domestic motor vehicle manufacturers in the United States, each having 
fewer than 1,000 employees. Although the cost for an ESC system is 
relatively high, we believe that these manufacturers would be able to 
pass the associated costs on to purchasers without decreasing sales 
volume, because the demand for these high-end, luxury vehicles tends to 
be inelastic and the increase in total vehicle cost is expected to be 
only 0.2-1.1 percent.
    There are a significant number of final-stage manufacturers and 
alterers that could be impacted by the proposed rule for ESC, some of 
which buy incomplete vehicles. However, final-stage manufacturers and 
alterers typically do not modify the brake system of the vehicle, so 
the original manufacturer's certification of the ESC system should pass 
through for these vehicles. We believe that increased costs associated 
with ESC would impact all such final-stage manufacturers and alterers 
equally, and that such costs would be passed on to consumers. 
Furthermore, we have no reason to believe that an average cost of $90 
per passenger car and $29 per truck will cause a significant decline in 
overall vehicle sales.
    We do not expect manufacturers of ESC systems to be classified as 
small businesses.

D. Executive Order 13132 (Federalism)

    Executive Order 13132 sets forth principles of federalism and the 
related policies of the Federal government. NHTSA has analyzed this 
rule in accordance with the principles and criteria set forth in 
Executive Order 13132, Federalism, and has determined that it does not 
have sufficient Federal implications to warrant consultation with State 
and local officials or the preparation of a Federalism summary impact 
statement. The rule will not have any substantial impact on the States, 
or on the current Federal-State relationship, or on the current 
distribution of power and responsibilities among the various local 
officials. However, under 49 U.S.C. 30103, whenever a Federal motor 
vehicle safety standard is in effect, a State may not adopt or maintain 
a safety standard applicable to the same aspect of performance which is 
not identical to the Federal standard, except to the extent that the 
state requirement imposes a higher level of performance and applies 
only to vehicles procured for the State's use.

E. Executive Order 12988 (Civil Justice Reform)

    Pursuant to Executive Order 12988, ``Civil Justice Reform'' (61 FR 
4729, February 7, 1996), the agency has considered whether this 
proposed rule would have any retroactive effect. This proposed rule 
would not have any retroactive effect. Under 49 U.S.C. 30103, whenever 
a Federal motor vehicle safety standard is in effect, a State may not 
adopt or maintain a safety standard applicable to the same aspect of 
performance of a motor vehicle or motor vehicle equipment which is not 
identical to the Federal standard, except to the extent that the State 
requirement imposes a higher level of performance and applies only to 
vehicles procured for the State's use. 49 U.S.C. 30161 sets forth a 
procedure for judicial review of final rules establishing, amending, or 
revoking Federal motor vehicle safety standards. That section does not 
require submission of a petition for reconsideration or other 
administrative proceedings before parties may file suit in court.

F. Executive Order 13045 (Protection of Children From Environmental 
Health and Safety Risks)

    Executive Order 13045, ``Protection of Children from Environmental 
Health and Safety Risks'' (62 FR 19855, April 23, 1997), applies to any 
rule that: (1) Is determined to be ``economically significant'' as 
defined under Executive Order 12866, and (2) concerns an environmental, 
health, or safety risk that the agency has reason to believe may have a 
disproportionate effect on children. If the regulatory action meets 
both criteria, the agency must evaluate the environmental health or 
safety effects of the planned rule on children, and explain why the 
planned regulation

[[Page 54737]]

is preferable to other potentially effective and reasonably feasible 
alternatives considered by the agency.
    Although the proposed rule for ESC has been determined to be an 
economically significant regulatory action under Executive Order 12866, 
the problems associated with loss of vehicle control equally impact all 
persons riding in a vehicle, regardless of age. Consequently, the 
proposed rule does not involve a decision based on environmental, 
health, or safety risks that disproportionately affect children and 
would not necessitate further analyses under Executive Order 13045.

G. Paperwork Reduction Act

    Under the Paperwork Reduction Act of 1995 (PRA), 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. The 
Department of Transportation is submitting the following information 
collection request to OMB for review and clearance under the PRA.
    Agency: National Highway Traffic Safety Administration (NHTSA).
    Title: Phase-In Production Reporting Requirements for Electronic 
Stability Control Systems.
    Type of Request: Routine.
    OMB Clearance Number: 2127-New.
    Form Number: This collection of information will not use any 
standard forms.
    Affected Public: The respondents are manufacturers of passenger 
cars, multipurpose passenger vehicles, trucks, and buses having a gross 
vehicle weight rating of 4,536 Kg (10,000 pounds) or less. The agency 
estimates that there are about 21 such manufacturers.
    Estimate of the Total Annual Reporting and Recordkeeping Burden 
Resulting From the Collection of Information: NHTSA estimates that the 
total annual hour burden is 42 hours.
    Estimated Costs: NHTSA estimates that the total annual cost burden, 
in U.S. dollars, will be $2,100. No additional resources would be 
expended by vehicle manufacturers to gather annual production 
information because they already compile this data for their own uses.
    Summary of Collection of Information: This collection would require 
manufacturers of passenger cars, multipurpose passenger vehicles, 
trucks, and buses with a gross vehicle weight rating of 4,536 Kg 
(10,000 pounds) or less to provide motor vehicle production data for 
the following three years: September 1, 2008 to August 31, 2009; 
September 1, 2009 to August 31, 2010; and September 1, 2010 to August 
31, 2011.
    Description of the Need for the Information and the Proposed Use of 
the Information: The purpose of the reporting requirements will be to 
aid NHTSA in determining whether a manufacturer has complied with the 
requirements of Federal Motor Vehicle Safety Standard No. 126, 
Electronic Stability Control Systems, during the phase-in of those 
requirements. NHTSA requests comments on the agency's estimates of the 
total annual hour and cost burdens resulting from this collection of 
information. These comments must be received on or before October 18, 
2006.

H. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (NTTAA), Public Law 104-113, section 12(d) (15 U.S.C. 272) 
directs NHTSA to use voluntary consensus standards in its regulatory 
activities unless doing so would be inconsistent with applicable law or 
otherwise impractical. 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 Society of Automotive 
Engineers (SAE). The NTTAA directs NHTSA to provide Congress, through 
OMB, explanations when the agency decides not to use available and 
applicable voluntary consensus standards. The NTTAA does not apply to 
symbols.
    The equipment requirements of this standard are based (with minor 
modifications) on the SAE Surface Vehicle Information Report on 
Automotive Stability Enhancement Systems J2564 Rev JUN2004 that 
provides an industry consensus definition of an ESC system. However, 
there is no voluntary consensus standard for ESC that contains any 
specifications for a performance test.

I. Unfunded Mandates Reform Act

    Section 202 of the Unfunded Mandates Reform Act of 1995 (UMRA) 
requires Federal 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 expenditure by State, local or 
tribal governments, in the aggregate, or by the private sector, of more 
than $100 million in any one year (adjusted for inflation with base 
year of 1995, so currently about $118 million in 2004 dollars). Before 
promulgating a rule for which a written statement is needed, section 
205 of the UMRA generally requires NHTSA to identify and consider a 
reasonable number of regulatory alternatives and adopt the least 
costly, most cost-effective, or least burdensome alternative that 
achieves the objectives of the rule. The provisions of section 205 do 
not apply when they are inconsistent with applicable law. Moreover, 
section 205 allows NHTSA to adopt an alternative other than the least 
costly, most cost-effective or least burdensome alternative if we 
publish with the final rule an explanation why that alternative was not 
adopted.
    This proposal would not result in the expenditure by State, local, 
or tribal governments, in the aggregate, of more than $118 million 
annually, but it would result in the expenditure of that magnitude by 
vehicle manufacturers and/or their suppliers.
    In this proposed rule, the agency is presenting not only its 
proposed regulatory approach for ESC, but also the regulatory 
alternatives it has considered. In addition, as part of the public 
comment process, the agency is open to suggestions regarding ways to 
promote flexibility and to minimize costs of compliance, while 
achieving the safety purposes of the Safe, Accountable, Flexible, 
Efficient Transportation Equity Act: A Legacy for Users of 2005.

J. National Environmental Policy Act

    NHTSA has analyzed this proposed rulemaking action for the purposes 
of the National Environmental Policy Act. The agency has determined 
that implementation of this action would not have any significant 
impact on the quality of the human environment.

K. Regulation Identifier Number (RIN)

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

L. Privacy Act

    Please note that anyone is able to search the electronic form of 
all comments received into any of our dockets by the name of the 
individual submitting the comment (or signing the comment, if submitted 
on behalf of an association, business, labor union, etc.). You may 
review DOT's complete

[[Page 54738]]

Privacy Act Statement in the Federal Register published on April 11, 
2000 (Volume 65, Number 70; pages 19477-78) or you may visit http://dms.dot.gov.
BILLING CODE 4910-59-P

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Figures to Preamble
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Proposed Regulatory Text

List of Subjects in 49 CFR Parts 571 and 585

    Imports, Motor vehicle safety, Report and recordkeeping 
requirements, Tires.

    In consideration of the foregoing, NHTSA is proposing to amend 49 
CFR parts 571 and 585 as follows:

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

    1. 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 1.50.

    2. Section 571.101 is amended by revising Table 1 to read as 
follows:


Sec.  571.101  Standard No. 101; Controls and displays.

* * * * *

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BILLING CODE 4910-59-C

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* * * * *
    3. Section 571.126 is added to read as follows:


Sec.  571.126  Standard No. 126; Electronic stability control systems.

    S1. Scope. This standard establishes performance and equipment 
requirements for electronic stability control (ESC) systems.
    S2. Purpose. The purpose of this standard is to reduce the number 
of deaths and injuries that result from crashes in which the driver 
loses directional control of the vehicle.
    S3. Application. This standard applies to passenger cars, 
multipurpose passenger vehicles, trucks, and buses with a gross vehicle 
weight rating of 4,536 kilograms (10,000 pounds) or less, according to 
the phase-in schedule specified in S8 of this standard.
    S4. Definitions.
    Ackerman Steer Angle means the angle whose tangent is the wheelbase 
divided by the radius of the turn at a very low speed.
    Electronic Stability Control System or ESC System means a system 
that has all of the following attributes:
    (1) That augments vehicle directional stability by applying and 
adjusting the vehicle brakes individually to induce correcting yaw 
torques to a vehicle;
    (2) That is computer controlled with the computer using a closed-
loop algorithm to limit vehicle oversteer and to limit vehicle 
understeer when appropriate;
    (3) That has a means to determine the vehicle's yaw rate and to 
estimate its side slip;
    (4) That has a means to monitor driver steering inputs, and
    (5) That is operational over the full speed range of the vehicle 
(except below a low-speed threshold where loss of control is unlikely).
    Oversteer means a condition in which the vehicle's yaw rate is 
greater than the yaw rate that would occur at the vehicle's speed as 
result of the Ackerman Steer Angle.
    Sideslip or side slip angle means the arctangent of the lateral 
velocity of the center of gravity of the vehicle divided by the 
longitudinal velocity of the center of gravity.
    Understeer means a condition in which the vehicle's yaw rate is 
less than the yaw rate that would occur at the vehicle's speed as 
result of the Ackerman Steer Angle.
    Yaw rate means the rate of change of the vehicle's heading angle 
measured in degrees/second of rotation about a vertical axis through 
the vehicle's center of gravity.
    S5. Requirements. Subject to the phase-in set forth in S8, each 
vehicle must be equipped with an ESC system that meets the requirements 
specified in S5 under the test conditions specified in S6 and the test 
procedures specified in S7 of this standard.
    S5.1 Required Equipment. Vehicles to which this standard applies 
must be equipped with an electronic stability control system that:
    S5.1.1 Is capable of applying all four brakes individually and has 
a control algorithm that utilizes this capability.
    S5.1.2 Is operational during all phases of driving including 
acceleration, coasting, and deceleration (including braking), except 
when the driver has disabled ESC or the vehicle is below a low speed 
threshold where loss of control is unlikely.
    S5.1.3 Remains operational when the antilock brake system or 
traction control system is activated.
    S5.2 Performance Requirements. During each test performed under the 
test conditions of S6 and the test procedure of S7.9, the vehicle with 
the ESC system engaged must satisfy the stability criteria of S5.2.1 
and S5.2.2, and it must satisfy the responsiveness criterion of S5.2.3 
during each of those tests conducted with a steering angle amplitude of 
180 degrees or greater.
    S5.2.1 The yaw rate measured one second after completion of the 
sine with dwell steering input (time T0 + 1 in Figure 1) 
must not exceed 35 percent of the first peak value of yaw velocity 
recorded after the beginning of the dwell period
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during the same test run, and
    S5.2.2 The yaw rate measured 1.75 seconds after completion of the 
sine with dwell steering input must not exceed 20 percent of the first 
peak value of yaw velocity recorded after the beginning of the dwell 
period during the same test run.
    S5.2.3 The lateral displacement of the vehicle center of gravity 
with respect to its initial straight path must be at least 1.83 m (6 
feet) when computed 1.07 seconds after initiation of steering.
    S5.2.3.1 The computation of lateral displacement is performed using 
double integration with respect to time of the measurement of lateral 
acceleration at the vehicle center of gravity, as expressed by the 
formula:

Lateral Displacement = [int][int]Ayc.g.dt

    S5.2.3.2 Time, t = 0 for the integration operation is the instant 
of steering initiation.
    S5.3 ESC Malfunction. The vehicle must be equipped with a telltale 
that provides a warning to the driver not more than two minutes after 
the occurrence of one or more malfunctions that affect the generation 
or transmission of control or response signals in the vehicle's 
electronic stability control system. The ESC malfunction telltale:
    S5.3.1 Must be mounted inside the occupant compartment in front of 
and in clear view of the driver;
    S5.3.2 Must be identified by the symbol shown for ``ESC Malfunction 
Telltale'' in Table 1 of Standard No. 101 (49 CFR 571.101);
    S5.3.3 Must remain continuously illuminated under the conditions 
specified in S5.3 for as long as the malfunction(s) exists, whenever 
the ignition locking system is in the ``On'' (``Run'') position; and
    S5.3.4 Except as provided in paragraph S5.3.5, each 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 ``On'' (``Run'') and ``Start'' that is designated by 
the manufacturer as a check position.
    S5.3.5 The ESC malfunction telltale need not be activated when a 
starter interlock is in operation.
    S5.3.6 The ESC malfunction telltale must extinguish after the 
malfunction has been corrected.
    S5.3.7 The manufacturer may use the ESC malfunction telltale in a 
flashing mode to indicate ESC operation.
    S5.4 ESC Off Switch and Telltale. The manufacturer may include a 
driver selectable switch that places the ESC system in a mode in which 
it will not satisfy the performance requirements of S5.2.1, S5.2.2 and 
S5.2.3 provided that:
    S5.4.1 The vehicle's ESC system must always return to a mode that 
satisfies the requirements of S5.1 and S5.2 at the initiation of each 
new ignition cycle, regardless of what mode the driver had previously 
selected. If the system has more than one mode that satisfies these 
requirements, the default mode must be the mode that satisfies the 
performance requirements of S5.2 by the greatest margin.
    S5.4.2 The vehicle manufacturer must provide a telltale indicating 
that the vehicle has been put into a mode that renders it unable to 
satisfy the requirements of S5.2.1, S5.2.2 and S5.2.3.
    S5.4.3 The ``ESC Off'' switch and telltale must be identified by 
the symbol shown for ``ESC Off'' in Table 1 of Standard No. 101 (49 CFR 
571.101).
    S5.4.4 The ``ESC Off'' telltale must be mounted inside the occupant

[[Page 54750]]

compartment in front of and in clear view of the driver.
    S5.4.5 The ``ESC Off'' telltale remain continuously illuminated for 
as long as the ESC is in a mode that renders it unable to satisfy the 
requirements of S5.2.1, S5.2.2 and S5.2.3, and
    S5.4.6 Except as provided in paragraph S5.4.7, each ``ESC Off'' 
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 ``On'' (``Run'') and ``Start'' that is designated by 
the manufacturer as a check position.
    S5.4.7 The ``ESC Off'' telltale need not be activated when a 
starter interlock is in operation.
    S5.4.8 The ``ESC Off'' telltale must extinguish after the ESC 
system has been returned to its fully functional default mode.
    S6. Test Conditions.
    S6.1. Ambient conditions.
    S6.1.1 The ambient temperature is between 0 [deg]C (32 [deg]F) and 
40 [deg]C (104 [deg]F).
    S6.1.2 The maximum wind speed is no greater than 10m/s (22 mph).
    S6.2. Road test surface.
    S6.2.1 The tests are conducted on a dry, uniform, solid-paved 
surface. Surfaces with irregularities and undulations, such as dips and 
large cracks, are unsuitable.
    S6.2.2 The road test surface must produce a peak friction 
coefficient (PFC) of 0.9  0.05 when measured using an 
American Society for Testing and Materials (ASTM) E1136 standard 
reference test tire, in accordance with ASTM Method E 1337-90, at a 
speed of 64.4 km/h (40 mph), without water delivery.
    S6.2.3 The test surface has a consistent slope between level and 
2%. All tests are to be initiated in the direction of positive slope 
(uphill).
    S6.3 Vehicle conditions.
    S6.3.1 The ESC system is enabled for all testing.
    S6.3.2 Test Weight. The vehicle is loaded with the fuel tank filled 
to at least 75 percent of capacity, and total interior load of 168 kg 
(370 lbs) comprised of the test driver, approximately 59 kg (130 lbs) 
of test equipment (automated steering machine, data acquisition system 
and the power supply for the steering machine), and ballast as required 
by differences in the weight of test drivers and test equipment.
    S6.3.3 Tires. The vehicle is tested with the tires installed on the 
vehicle at time of initial vehicle 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. Tubes may be installed to prevent tire de-beading.
    S6.3.4 Outriggers. Outriggers must be used for tests of Sport 
Utility Vehicles (SUVs), and they are permitted on other test vehicles 
if deemed necessary for driver safety.
    S6.3.5 A steering machine programmed to execute the required 
steering pattern must be used in S7.5.2, S7.5.3, S7.6 and S7.9.
    S7. Test Procedure.
    S7.1 Inflate the vehicles' tires to the cold tire inflation 
pressure(s) provided on the vehicle's placard or the tire inflation 
pressure label.
    S7.2 Telltale bulb check. With the vehicle stationary and the 
ignition locking system in the ``Lock'' or ``Off'' position, activate 
the ignition locking system to the ``On'' (``Run'') position or, where 
applicable, the appropriate position for the lamp check. The ESC system 
must perform a check of lamp function for the ESC malfunction telltale, 
and if equipped, the ``ESC Off'' telltale, as specified in S5.3.4 and 
S5.4.6.
    S7.3 ``ESC Off'' switch check. For vehicles equipped with an ``ESC 
Off'' feature, with the vehicle stationary and the ignition locking 
system in the ``Lock'' or ``Off'' position, activate the ignition 
locking system to the ``On'' (``Run'') position. Activate the ``ESC 
Off'' switch and verify that the ``ESC Off'' telltale is illuminated. 
Turn the ignition locking system to the ``Lock'' or ``Off'' position. 
Again, activate the ignition locking system to the ``On'' (``Run'') 
position and verify that the ``ESC Off'' telltale has extinguished 
indicating that the ESC system has been reactivated as specified in 
S5.4.
    S7.4 Brake Conditioning. Condition the vehicle brakes as follows:
    S7.4.1 Ten stops are performed from a speed of 56 km/h (35 mph), 
with an average deceleration of approximately 0.5 g.
    S7.4.2 Immediately following the series of 56 km/h (35 mph) stops, 
three additional stops are performed from 72 km/h (45 mph).
    S7.4.3 When executing the stops in S7.4.2, sufficient force is 
applied to the brake pedal to activate the vehicle's antilock brake 
system (ABS) for a majority of each braking event.
    S7.4.4 Following completion of the final stop in S7.4.2, the 
vehicle is driven at a speed of 72 km/h (45 mph) for five minutes to 
cool the brakes.
    S7.5 Tire Conditioning. Condition the tires using the following 
procedure to wear away mold sheen and achieve operating temperature 
immediately before beginning the test runs of S7.6 and S7.9.
    S7.5.1 The test vehicle is driven around a circle 30 meters (100 
feet) in diameter at a speed that produces a lateral acceleration of 
approximately 0.5 to 0.6 g for three clockwise laps followed by three 
counterclockwise laps.
    S7.5.2 Using a sinusoidal steering pattern at a frequency of 1 Hz, 
a peak steering wheel angle amplitude corresponding to a peak lateral 
acceleration of 0.5-0.6 g, and a vehicle speed of 56 km/h (35 mph), the 
vehicle is driven through four passes performing 10 cycles of 
sinusoidal steering during each pass.
    S7.5.3 The steering wheel angle amplitude of the final cycle of the 
final pass is twice that of the other cycles. The maximum time 
permitted between all laps and passes is five minutes.
    S7.6 Slowly Increasing Steer Test. The vehicle is subjected to two 
series of runs of the Slowly Increasing Steer Test using a steering 
pattern that increases by 13.5 degrees per second until a lateral 
acceleration of approximately 0.5 g is obtained. Three repetitions are 
performed for each test series. One series uses counterclockwise 
steering, and the other series uses clockwise steering. The maximum 
time permitted between each test run is five minutes.
    S7.6.1 From the Slowly Increasing Steer tests, the quantity ``A'' 
is determined. ``A'' is the steering wheel angle in degrees that 
produces a steady state lateral acceleration of 0.3 g for the test 
vehicle. Utilizing linear regression, A is calculated, to the nearest 
0.1 degrees, from each of the six Slowly Increasing Steer tests. The 
absolute value of the six A's calculated is averaged and rounded to the 
nearest degree to produce the final quantity, A, used below.
    S7.7 After the quantity A has been determined, without replacing 
the tires, the tire conditioning procedure described in S7.5 is 
performed immediately prior to conducting the Sine with Dwell Test of 
S7.9.
    S7.8 Check that the ESC system is enabled by ensuring that the ESC 
malfunction and ``ESC Off'' (if provided) telltales are not 
illuminated.
    S7.9 Sine with Dwell Test of Oversteer Intervention and 
Responsiveness. The vehicle is subjected to two series of test runs 
using a steering pattern of a sine wave at 0.7 Hz frequency with a 500 
ms delay beginning at the second peak amplitude as shown in Figure 2 
(the Sine with Dwell tests). One series uses counterclockwise steering 
for the first half cycle, and the other series uses

[[Page 54751]]

clockwise steering for the first half cycle. The maximum time permitted 
between each test run is five minutes.
    S7.9.1 The steering motion is initiated with the vehicle coasting 
in high gear at 80  1 km/h (50  1 mph).
    S7.9.2 In each series of test runs, the steering amplitude is 
increased from run to run, by 0.5A, provided that no such run will 
result in a steering amplitude greater than that of the final run 
specified in S7.9.4.
    S7.9.3 The steering amplitude for the initial run of each series is 
1.5A where A is the steering wheel angle determined in S7.6.1.
    S7.9.4 The steering amplitude of the final run in each series is 
the greater of 6.5A or 270 degrees.
    S7.9.5 Notwithstanding S7.9.4, the test is terminated after a run 
in which the vehicle does not satisfy S5.2.1 or S5.2.2.
    S7.10 ESC Malfunction Detection.
    S7.10.1 Simulate one or more ESC malfunction(s) by disconnecting 
the power source to any ESC component, or disconnecting any electrical 
connection between ESC components. When simulating an ESC malfunction, 
the electrical connections for the telltale lamp(s) are not to be 
disconnected.
    S7.10.2 With the vehicle stationary and the ignition locking system 
in the ``Lock'' or ``Off'' position, activate the ignition locking 
system to the ``On'' (``Run'') position. Verify that within two minutes 
of activating the ignition locking system, the ESC malfunction 
indicator illuminates in accordance with S5.3.
    S7.10.3 Deactivate the ignition locking system to the ``Off'' or 
``Lock'' position. After a five-minute period, activate the vehicle's 
ignition locking system to the ``On'' (``Run'') position. Verify that 
the ESC malfunction indicator again illuminate to signal a malfunction 
and remains illuminated as long as the ignition locking system is in 
the ``On'' (``Run'') position.
    S7.10.4 Restore the ESC system to normal operation and verify that 
the telltale has extinguished.
    S8 Phase-in schedule.
    S8.1 Vehicles manufactured on or after September 1, 2008, and 
before September 1, 2009. For vehicles manufactured on or after 
September 1, 2008, and before September 1, 2009, the number of vehicles 
complying with this standard must not be less than 30 percent of:
    (a) The manufacturer's average annual production of vehicles 
manufactured on or after September 1, 2005, and before September 1, 
2008; or
    (b) The manufacturer's production on or after September 1, 2008, 
and before September 1, 2009.
    S8.2 Vehicles manufactured on or after September 1, 2009, and 
before September 1, 2010. For vehicles manufactured on or after 
September 1, 2009, and before September 1, 2010, the number of vehicles 
complying with this standard must not be less than 60 percent of:
    (a) The manufacturer's average annual production of vehicles 
manufactured on or after September 1, 2006, and before September 1, 
2009; or
    (b) The manufacturer's production on or after September 1, 2009, 
and before September 1, 2010.
    S8.3 Vehicles manufactured on or after September 1, 2010, and 
before September 1, 2011. For vehicles manufactured on or after 
September 1, 2010, and before September 1, 2011, the number of vehicles 
complying with this standard must not be less than 90 percent of:
    (a) The manufacturer's average annual production of vehicles 
manufactured on or after September 1, 2007, and before September 1, 
2010; or
    (b) The manufacturer's production on or after September 1, 2010, 
and before September 1, 2011.
    S8.4 Vehicles manufactured on or after September 1, 2011. All 
vehicles manufactured on or after September 1, 2011 must comply with 
this standard.
    S8.5 Calculation of complying vehicles.
    (a) For purposes of complying with S8.1, a manufacturer may count a 
vehicle if it is certified as complying with this standard and is 
manufactured on or after (date to be inserted that is 60 days after 
publication date of final rule), but before September 1, 2009.
    (b) For purpose of complying with S8.2, a manufacturer may count a 
vehicle if it:
    (1)(i) Is certified as complying with this standard and is 
manufactured on or after (date to be inserted that is 60 days after 
date of publication of the final rule), but before September 1, 2010; 
and
    (ii) Is not counted toward compliance with S8.1; or
    (2) Is manufactured on or after September 1, 2009, but before 
September 1, 2010.
    (c) For purposes of complying with S8.3, a manufacturer may count a 
vehicle if it:
    (1)(i) Is certified as complying with this standard and is 
manufactured on or after (date to be inserted that is 60 days after 
date of publication of the final rule), but before September 1, 2011; 
and
    (ii) Is not counted toward compliance with S8.1 or S8.2; or
    (2) Is manufactured on or after September 1, 2010, but before 
September 1, 2011.
    S8.6 Vehicles produced by more than one manufacturer.
    S8.6.1 For the purpose of calculating average annual production of 
vehicles for each manufacturer and the number of vehicles manufactured 
by each manufacturer under S8.1 through S8.4, a vehicle produced by 
more than one manufacturer must be attributed to a single manufacturer 
as follows, subject to S8.6.2:
    (a) A vehicle that is imported must be attributed to the importer.
    (b) A vehicle manufactured in the United States by more than one 
manufacturer, one of which also markets the vehicle, must be attributed 
to the manufacturer that markets the vehicle.
    S8.6.2 A vehicle produced by more than one manufacturer must be 
attributed to any one of the vehicle's manufacturers specified by an 
express written contract, reported to the National Highway Traffic 
Safety Administration under 49 CFR Part 585, between the manufacturer 
so specified and the manufacturer to which the vehicle would otherwise 
be attributed under S8.6.1.
    S8.7 Small volume manufacturers.
    Vehicles manufactured during any of the three years of the 
September 1, 2008 through August 31, 2011 phase-in by a manufacturer 
that produces fewer than 5,000 vehicles for sale in the United States 
during that year are not subject to the requirements of S8.1, S8.2, 
S8.3, and S8.5
    S8.8 Final-stage manufacturers and alterers.
    Vehicles that are manufactured in two or more stages or that are 
altered (within the meaning of 49 CFR 567.7) after having previously 
been certified in accordance with Part 567 of this chapter are not 
subject to the requirements of S8.1 through S8.5. Instead, all vehicles 
produced by these manufacturers on or after September 1, 2012 must 
comply with this standard.
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PART 585--PHASE-IN REPORTING REQUIREMENTS

    4. The authority citation for part 585 continues to read as 
follows:

    Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166; 
delegation of authority at 49 CFR 1.50.

    5. Subpart I is added to read as follows:

Sec.
Subpart I--Electronic Stability Control System Phase-in Reporting 
Requirements
585.81 Scope.
585.82 Purpose.
585.83 Applicability.
585.84 Definitions.
585.85 Response to inquiries.
585.86 Reporting requirements.
585.87 Records.
585.88 Petition to extend period to file report.

Subpart I--Electronic Stability Control System Phase-in Reporting 
Requirements


Sec.  585.81  Scope.

    This subpart establishes requirements for manufacturers of 
passenger cars, multipurpose passenger vehicles, trucks, and buses with 
a gross vehicle weight rating of 4,536 kilograms (10,000 pounds) or 
less to submit a report, and maintain records related to the report, 
concerning the number of such vehicles that meet the requirements of 
Standard No. 126, Electronic stability control systems (49 CFR 
571.126).


Sec.  585.82  Purpose.

    The purpose of these reporting requirements is to assist the 
National Highway Traffic Safety Administration in determining whether a 
manufacturer has complied with Standard No. 126 (49 CFR 571.126).


Sec.  585.83  Applicability.

    This subpart applies to manufacturers of passenger cars, 
multipurpose passenger vehicles, trucks, and buses with a gross vehicle 
weight rating of 4,536 kilograms (10,000 pounds) or less. However, this 
subpart does not apply to manufacturers whose production consists 
exclusively of vehicles manufactured in two or more stages, and 
vehicles that are altered after previously having been certified in 
accordance with part 567 of this chapter. In addition, this subpart 
does not apply to manufacturers whose production of motor vehicles for 
the United States market is less than 5,000 vehicles in a production 
year.


Sec.  585.84  Definitions.

    For the purposes of this subpart: Production year means the 12-
month period between September 1 of one year and August 31 of the 
following year, inclusive.


Sec.  585.85  Response to inquiries.

    At any time prior to August 31, 2011, each manufacturer must, upon 
request from the Office of Vehicle Safety Compliance, provide 
information identifying the vehicles (by make, model, and vehicle 
identification number) that have been certified as complying with 
Standard No. 126 (49 CFR 571.126). The manufacturer's designation of a 
vehicle as a certified vehicle is irrevocable. Upon request, the 
manufacturer also must specify whether it intends to utilize carry-
forward credits, and the vehicles to which those credits relate.


Sec.  585.86  Reporting requirements.

    (a) General reporting requirements. Within 60 days after the end of 
the production years ending August 31, 2009, August 31, 2010, and 
August 31, 2011, each manufacturer must submit a report to the National 
Highway Traffic Safety Administration concerning its compliance with 
Standard No. 126 (49 CFR 571.126) for its passenger cars, multipurpose 
passenger vehicles, trucks, and buses with a gross vehicle weight 
rating of less than 4,536 kilograms (10,000 pounds) produced in that 
year. Each report must--
    (1) Identify the manufacturer;
    (2) State the full name, title, and address of the official 
responsible for preparing the report;
    (3) Identify the production year being reported on;
    (4) Contain a statement regarding whether or not the manufacturer 
complied with the requirements of Standard No. 126 (49 CFR 571.126) for 
the period covered by the report and the basis for that statement;
    (5) Provide the information specified in paragraph (b) of this 
section;
    (6) Be written in the English language; and
    (7) Be submitted to: Administrator, National Highway Traffic Safety 
Administration, 400 Seventh Street, SW., Washington, DC 20590.
    (b) Report content.
    (1) Basis for statement of compliance. Each manufacturer must 
provide the number of passenger cars, multipurpose passenger vehicles, 
trucks, and buses with a gross vehicle weight rating of 4,536 kilograms 
(10,000 pounds) or less, manufactured for sale in the United States for 
each of the three previous production years, or, at the manufacturer's 
option, for the current production year. A new manufacturer that has 
not previously manufactured these vehicles for sale in the United 
States must report the number of such vehicles manufactured during the 
current production year.
    (2) Production. Each manufacturer must report for the production 
year for which the report is filed: The number of passenger cars, 
multipurpose passenger vehicles, trucks, and buses with a gross vehicle 
weight rating of 4,536 kilograms (10,000 pounds) or less that meet 
Standard No. 126 (49 CFR 571.126).
    (3) Statement regarding compliance. Each manufacturer must provide 
a statement regarding whether or not the manufacturer complied with the 
ESC requirements as applicable to the period covered by the report, and 
the basis for that statement. This statement must include an 
explanation concerning the use of any carry-forward credits.
    (4) Vehicles produced by more than one manufacturer. Each 
manufacturer whose reporting of information is affected by one or more 
of the express written contracts permitted by S8.6.2 of Standard No. 
126 (49 CFR 571.126) must:
    (i) Report the existence of each contract, including the names of 
all parties to the contract, and explain how the contract affects the 
report being submitted.
    (ii) Report the actual number of vehicles covered by each contract.


Sec.  585.87  Records.

    Each manufacturer must maintain records of the Vehicle 
Identification Number for each vehicle for which information is 
reported under Sec.  585.86(b)(2) until December 31, 2013.


Sec.  585.88  Petition to extend period to file report.

    A manufacturer may petition for extension of time to submit a 
report under this Part. A petition will be granted only if the 
petitioner shows good cause for the extension and if the extension is 
consistent with the public interest. The petition must be received not 
later than 15 days before expiration of the time stated in Sec.  
585.86(a). The filing of a petition does not automatically extend the 
time for filing a report. The petition must be submitted to: 
Administrator, National Highway Traffic Safety Administration, 400 
Seventh Street, SW., Washington, DC 20590.

    Issued: September 7, 2006.
Stephen R. Kratzke,
Associate Administrator for Rulemaking.
[FR Doc. 06-7598 Filed 9-14-06; 10:00 am]
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