[Federal Register Volume 60, Number 239 (Wednesday, December 13, 1995)]
[Rules and Regulations]
[Pages 63965-63981]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-30375]



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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. 92-29; Notice 7; Docket No. 93-06; Notice 4; Docket No. 93-
07; Notice 4]
RIN 2127-AF96; 2127-AF97; 2127-AF98; 2127-AF99


Federal Motor Vehicle Safety Standards; Stability and Control of 
Medium and Heavy Vehicles During Braking; and Stopping Distance 
Requirements

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

ACTION: Final rule, petitions for reconsideration.

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SUMMARY: This document responds to petitions for reconsideration of a 
final rule that amended Standard No. 105, Hydraulic Brake Systems, and 
Standard No. 121, Air Brake Systems, to require medium and heavy 
vehicles be equipped with an antilock brake system (ABS). This document 
also responds to petitions for reconsideration of final rules that 
established 60 mph stopping distance requirements for hydraulic-braked 
heavy vehicles and reinstated such requirements for air-braked heavy 
vehicles.

DATES: Effective Dates: The amendments to Sec. 571.101 are effective 
January 12, 1996, the amendments to Sec. 571.105 are effective March 1, 
1999, and amendments to Sec. 571.121 are effective March 1, 1997.
    Compliance dates: Compliance with the amendments to 49 CFR 571.101 
and 49 CFR 571.105 with respect to hydraulic-braked vehicles will be 
required on and after March 1, 1999. Compliance with 49 CFR 571.101 and 
49 CFR 571.121 with respect to air-braked tractors will be required on 
and after March 1, 1997 and compliance with 49 CFR 571.101 and 49 CFR 
571.121 with respect to air-braked trailers and single unit trucks and 
buses will be required on and after March 1, 1998.
    Petitions for Reconsideration: Any petitions for reconsideration of 
this rule must be received by NHTSA no later than January 12, 1996.

ADDRESSES: Petitions for reconsideration of this rule should refer to 
the above referenced docket numbers and should be submitted to: 
Administrator, National Highway Traffic Safety Administration, 400 
Seventh Street, S.W., Washington, D.C. 20590.

FOR FURTHER INFORMATION CONTACT:
    For non-legal issues: Mr. George Soodoo, Office of Crash Avoidance, 
National Highway Traffic Safety Administration, 400 Seventh Street SW., 
Washington, D.C. 20590 (202) 366-5892.
    For legal issues: Mr. Marvin L. Shaw, NCC-20, Rulemaking Division, 
Office of Chief Counsel, National Highway Traffic Safety 
Administration, 400 Seventh Street SW., Washington, D.C. 20590 (202) 
366-2992.

SUPPLEMENTARY INFORMATION:
I. Background
II. Petitions for Reconsideration
III. Definitions Related to Antilock Brake Systems
    A. Definition of Antilock Brake Systems
    B. Directly Controlled Wheel
    C. Independent Wheel Control
IV. Overall Brake Test Sequence
    A. Performance Test Sequence
    B. Brake Adjustment During Test Sequence
    C. Final Brake Inspection in Test Sequence
V. Braking-In-A-Curve Test
    A. General Considerations
    B. Type of Brake Application
    C. Number of Test Stops for Certification
    D. Initial Brake Temperature
VI. Stopping Distance Performance
    A. Stopping Distance Requirements
    B. Test Surface Specification
    C. Wheel Lockup Restrictions
    D. Burnish Procedure
    E. Definition of Nonsteerable Axle
VII. ABS Malfunction Indicator Lamps
    A. In-cab Malfunction Lamp for Trailer ABS
    B. Trailer-mounted ABS Malfunction Indicator
    C. Activation Protocol for Malfunction Indicators
    D. Signal Storage
    E. ABS Failed System Requirements
VIII. Power Source
    A. Separate Powering for Trailer ABS
    B. ABS Malfunction Signal Circuit and Ground
    C. Tractor Trailer ABS Interface Connector
IX. Applicability of Amendments and Leadtime
    A. Hydraulic-Braked Vehicles
    B. Class 3 Vehicles
    C. Four-Wheel Drive Vehicles
    D. Trailers and Dollies
X. Miscellaneous
    A. National Uniformity
    B. Publish Complete Regulatory Texts and Compliance Test 
Procedures
    C. Costs
    D. Corrections to Standard No. 101 and Standard No. 105

I. Background

    On March 10, 1995, NHTSA published three final rules that amended 
the agency's brake standards for medium and heavy vehicles.\1\ (60 FR 
13216). One of those final rules requires heavy vehicles to be equipped 
with an antilock brake system (ABS) to improve the directional 
stability and control of these vehicles during braking.\2\ The other 
two final rules announced NHTSA's decision to reinstate stopping 
distance requirements for air-braked heavy vehicles and to establish 
such requirements for hydraulic-braked heavy vehicles. (60 FR 13286, 
13297)

    \1\ Hereinafter referred to as ``heavy vehicles.''
    \2\ Hereinafter referred to as ``the ABS final rule.''
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    As specified in the ABS final rule, in addition to the ABS 
requirement, truck tractors are required to comply with a 30-mph 
braking-in-a-curve test using a full brake application on a low 
coefficient of friction surface representing a wet surface. All powered 
heavy vehicles are also required to be equipped with an in-cab lamp to 
indicate ABS malfunctions. Truck tractors and other towing vehicles are 
required to be equipped with two separate in-cab lamps: one indicating 
malfunctions in the towing vehicle ABS and the other indicating 
malfunctions in the ABS on one or more towed trailers and/or dollies. 
Trailers (including dollies) produced during an initial eight-year 
period are also required to be equipped with an external malfunction 

[[Page 63966]]
indicator that was to be visible to the driver through the rearview 
mirror of the towing vehicle.
    NHTSA issued the ABS final rule pursuant to the Motor Carrier Act 
of 1991, a part of the Intermodal Surface Transportation Efficiency Act 
(ISTEA) of 1991. Section 4012 of ISTEA directed the Secretary of 
Transportation to initiate rulemaking concerning methods for improving 
braking performance of new commercial motor vehicles,\3\ including 
truck tractors, trailers, and their dollies. Congress specifically 
directed that such a rulemaking examine antilock systems, means of 
improving brake compatibility, and methods of ensuring effectiveness of 
brake timing. The Act required that the rulemaking be consistent with 
the Motor Carrier Safety Act of 1984 (49 U.S.C. Sec. 31147) and be 
carried out pursuant to, and in accordance with, the National Traffic 
and Motor Vehicle Safety Act of 1966 (Safety Act) (49 U.S.C. Sec. 30101 
et seq.).

    \3\ Vehicles with a gross vehicle weight rating (GVWR) of 26,001 
pounds or greater.
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II. Petitions for Reconsideration

    NHTSA received petitions for reconsideration from the American 
Trucking Associations (ATA), the American Automobile Manufacturers 
Association (AAMA), the Truck Trailer Manufacturers Association (TTMA), 
the Heavy Duty Brake Manufacturers Council (HDBMC), the United Parcel 
Service (UPS), vehicle manufacturers, including Chrysler, Navistar, AM 
General, and brake or component manufacturers including Midland-Grau, 
Jenflo, AlliedSignal, Rockwell WABCO, Rockwell International, Kelsey-
Hayes, and Ferodo America.
    The petitioners generally agreed with NHTSA's decision to require 
all heavy vehicles to be equipped with ABS and to comply with the 
stopping distance requirements and to require truck tractors to comply 
with the braking-in-a-curve requirements. Nevertheless, they requested 
modifications of various aspects of those requirements. The issues 
raised by the petitioners include the definition of antilock brake 
systems and the wheels to which the ABS requirement applies, the ABS 
requirement's applicability to hydraulic-braked vehicles, the 
implementation schedule, certain aspects of the performance tests, 
certain aspects of the malfunction indicator requirements, and the 
requirements addressing trailer ABS powering. The agency responds to 
each of the issues raised by the petitioners throughout the remainder 
of the document.

III. Definitions Related to Antilock Brake Systems

A. Definition of Antilock Brake Systems

    In the ABS final rule, NHTSA decided to require that each heavy 
vehicle be equipped with an antilock brake system that satisfies the 
following definition:

    ``Antilock braking system'' means a portion of a service brake 
system that automatically controls the degree of rotational wheel 
slip during braking by:
    (1) Sensing the rate of angular rotation of the wheels;
    (2) Transmitting signals regarding the rate of wheel angular 
rotation to one or more devices which interpret those signals and 
generate responsive controlling output signals; and
    (3) Transmitting those controlling signals to one or more 
devices which adjust brake actuating forces in response to those 
signals.

    To meet this definition, an antilock braking system must be closed-
loop.\4\ With respect to the definition for ABS, the input is the act 
of sensing the rate of angular rotation of the wheels, which is 
typically done by a device known as a wheel speed sensor. The output is 
the act of transmitting responsive controlling output signals to a 
device or devices known as modulator valves that adjust brake actuating 
forces in response to those signals.

    \4\ A closed loop control system is one which examines the 
output of the system and adjusts the input to the system in response 
to that output. This inclusion of the output (or some function of 
the output) as part of the input to such a system is referred to as 
feedback.
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    Jenflo petitioned the agency to amend the definition of an antilock 
braking system so that the definition did not refer to components such 
as wheel speed sensors, control units, and modulators. Jenflo believes 
that it is possible to control rotational wheel slip and impending 
wheel lockup without monitoring these conditions, while still providing 
controlled stops. In its petition for reconsideration, Jenflo submitted 
56 pages of test data, but did not explain the relevance of the data to 
the vehicle's ABS performance.
    NHTSA has decided to deny Jenflo's petition to amend the definition 
of ABS so as to permit open-loop systems. In previous notices, the 
agency discussed in extensive detail the reasons for requiring a 
``closed-loop'' antilock system and for combining an equipment 
requirement with a dynamic test requirement for truck tractors. (60 FR 
13224-13228) NHTSA's definition permits any ABS, provided that it is a 
closed-loop system that ensures feedback between what is actually 
happening at the tire-road surface interface and what the device is 
doing to respond to changes in wheel slip. As many brake and vehicle 
manufacturers commented on the September 1993 NPRM, a device that 
satisfies these criteria is necessary to prevent wheel lockup under a 
wide variety of real world conditions, thereby significantly improving 
safety. In contrast, a definition that permitted open-loop systems 
would allow systems that would not necessarily prevent wheel lockup.
    NHTSA also stated that the desired safety benefits of ABS could 
currently be achieved only by means of both a specific equipment 
requirement for ABS and a dynamic performance test requirement 
applicable to truck tractors only. In its petition for reconsideration, 
Jenflo did not provide any information to support reliance solely on a 
dynamic performance requirement, or to support its statement that it is 
possible to control rotational wheel slip without monitoring wheel slip 
conditions. The agency therefore has decided to deny Jenflo's petition 
to amend the definition for antilock brake system.

B. Directly Controlled Wheel

    In the ABS final rule, the agency defined ``directly controlled 
wheel'' to mean a wheel at which the degree of rotational wheel slip is 
sensed and corresponding signals are transmitted to one or more 
modulators that adjust the brake actuating forces at that wheel. (60 FR 
13228-13230) The definition further stated that each modulator may also 
adjust the brake actuating forces at other wheels in response to the 
same signal or signals. NHTSA explained that, by ``directly controlled 
wheel,'' it meant that the signal provided at the wheel or on the axle 
of the wheel would directly modulate the braking forces of that wheel 
or axle.
    AAMA, Chrysler, and Kelsey Hayes petitioned the agency to revise 
the definition of ``directly controlled wheel'' to allow the use of a 
single in-differential 5 or in-axle wheel speed sensor to control 
the rear wheel slip. Chrysler indicated that all of its pickup trucks 
in the 10,000-12,000 pound gross vehicle weight rating (GVWR) class now 
successfully use this type of sensor.

    \5\  A differential is comprised of a set of gears which 
establish a constant equilibrium of torques between the left-side 
and right-side driven wheels, and which allow the outer wheels of a 
vehicle to rotate at a higher speed than the inner wheels during 
cornering.
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    After reviewing the petitions for reconsideration regarding in-axle 
sensors, NHTSA has decided to revise the definition of ``directly 
controlled wheel'' to allow wheel speeds to be sensed at any point on 
the axle shaft of 

[[Page 63967]]
the wheel. This includes any point between the wheel hub and the point 
where the axle shaft mates with the differential output shaft. The 
agency believes that this modification to the definition will permit 
the manufacture of proven antilock systems, without any detriment to 
safety. This amendment is reflected in the revised definition for 
``directly controlled wheel'' by adding the phrase ``either at that 
wheel or on the axle shaft for that wheel'' and allows two in-
differential sensors to transmit corresponding signals to one or more 
modulators that adjust the brake actuating forces at the wheels on that 
axle.
    NHTSA emphasizes that single in-differential sensors will only be 
allowed on light vehicles with GVWRs between 10,000 and 12,000 pounds. 
This limitation is reflected in S5.5.1 of Standard No. 105, which 
permits only vehicles with such GVWRs to provide direct wheel control 
by means of a single sensor in the drive line. The agency is concerned 
that sensing of rotational wheel slip at the ring gear or at other 
points on the driveline 6 forward of the drive axle, does not 
provide sufficiently precise measurements of wheel slip for effective 
ABS control on vehicles over 12,000 pounds. The braking distribution 
between the front and rear axles of heavy vehicles is different than on 
light vehicles, primarily because of the greater load-carrying capacity 
of heavy vehicles, which necessitates more braking at the rear wheels. 
As a result, greater braking efficiency is typically required at the 
rear wheels of heavy vehicles than on lighter vehicles. Based on the 
above considerations, the agency has decided to allow the use of a 
single in-axle or in-differential sensor, and include in-transmission 
sensors, for ABS control of rear wheel slip on vehicles with a GVWR 
between 10,000 and 12,000 pounds.

     6  The driveline constitutes those parts of the vehicle 
that transfer power from the transmission to the drive wheels, 
including the drive shaft, differential, and axle shafts of the 
driven wheel.
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    Rockwell WABCO requested that the agency change the definition of a 
``directly controlled wheel'' to ensure that the modulator for 
controlling the wheels of the front axle is not used to control the 
wheels of the rear axle, and vice versa.
    NHTSA has reviewed the definition of a ``directly controlled 
wheel'' and has concluded that it does not clearly state that, on 
single unit vehicles and full trailers, the same modulator should not 
be used to control both the front and rear axles. It is possible that 
the definition may be misinterpreted to allow a four sensor/one 
modulator (4S/1M) system on single unit vehicles and full trailers. As 
discussed in the final rule, it was the agency's intent to require at 
least one modulator for controlling the front axle(s) and at least one 
modulator for controlling the rear axle(s) of those vehicles. (60 FR 
13230) In revising the definition, the agency has added the phrase 
``that are on the same axle or in the same axle set,'' to make it clear 
that the modulator that controls a directly controlled wheel, can also 
control a wheel on the same axle or wheel(s) on other axles in the same 
tandem 7.

     7  An arrangement of two or more axles placed in proximity 
one behind the other.
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    Based on the above considerations, NHTSA has decided to amend the 
definition of directly controlled wheel as follows:

    ``Directly Controlled Wheel'' means a wheel for which the degree 
of rotational wheel slip is sensed, either at that wheel or on the 
axle shaft for that wheel, and corresponding signals are transmitted 
to one or more modulators that adjust the brake actuating forces at 
that wheel. Each modulator may also adjust the brake actuating 
forces at other wheels that are on the same axle or in the same axle 
set in response to the same signal(s).

(Italicized phrases are additions to the definition).

C. Independent Wheel Control

    In the ABS final rule, NHTSA defined ``independently controlled 
wheel'' to mean a directly controlled wheel for which there is a 
modulator that adjusts the brake actuating forces at that wheel, but 
not at any other wheel on the same axle.
    Jenflo petitioned the agency to delete the requirement for 
independent wheel control on truck tractors and issue what it called 
``performance only'' requirements. That company stated that requiring 
independent wheel control is unreasonably design- restrictive and is 
not a performance requirement.
    In the ABS final rule, NHTSA set forth the reasons for requiring 
independent control of at least one axle for truck tractors and the 
reasons for having more stringent requirements for truck tractors than 
for other types of vehicles. (60 FR 13230). The agency considers these 
reasons to be a sufficient basis for requiring independent control. 
Nevertheless, Jenflo has not addressed these reasons in the petition.
    AAMA requested confirmation that the ABS rule requires a truck 
tractor to have an ABS with at least four sensors and three modulators 
(which are also known as channels of control)(4S/3M), a single unit 
vehicle to have an ABS with at least four sensors and two modulators 
(4S/2M), and a semitrailer to have an ABS with at least two sensors and 
one modulator (2S/1M). NHTSA confirms the AAMA's interpretation. In 
addition, the agency notes that a full trailer will be required to have 
an ABS with at least four sensors and two modulators (4S/2M), and a 
hydraulic-braked single unit vehicle with a GVWR between 10,000 lbs. 
and 12,000 lbs. will be required to have at least three sensors and two 
modulators (3S/2M).

IV. Overall Brake Test Sequence

A. Performance Test Sequence

    In Table I of the stopping distance final rule for braked vehicles, 
NHTSA specified the sequence in which the brake tests are to be 
conducted for compliance testing, as follows:
    (1) Burnish.
    (2) Stops with vehicle at gross vehicle weight rating:
    (a) Straight line stop at 60 mph on a peak friction coefficient 
surface of 0.9, for a truck tractor with a loaded unbraked control 
trailer, or for a single-unit vehicle (straight line stop).
    (b) Braking-in-a-curve stop at 30 mph on a peak friction 
coefficient surface of 0.5, for a truck tractor with a loaded unbraked 
control trailer.
    (c) Emergency brake stops at 60 mph on a peak friction coefficient 
surface of 0.9, for a single-unit vehicle. Truck tractors are not 
required to be tested in the loaded condition.
    (3) Parking brake test with vehicle loaded to GVWR.
    (4) Stops with vehicle at unloaded weight plus up to 500 lbs.
    (a) Straight line stop at 60 mph on a peak friction coefficient 
surface of 0.9, for a truck tractor or for a single-unit vehicle.
    (b) Braking-in-a-curve stop at 30 mph service brake stops on a peak 
friction coefficient surface of 0.5, for a truck tractor.
    (c) Emergency brake stops at 60 mph on a peak friction coefficient 
surface of 0.9, for a truck tractor or for a single-unit vehicle.
    5. Parking brake test with vehicle at unloaded weight plus up to 
500 lbs.
    6. Final inspection of service brake system for condition of 
adjustment. (60 FR 13297)
    AAMA, HDBMC, Midland-Grau, and Navistar requested that the agency 
revise the performance test sequence in Standard No. 121 by placing 
both braking-in-a-curve tests for truck tractors immediately after the 
burnish. These petitioners stated that such a change would result in 
certain 

[[Page 63968]]
advantages, including (1) allowing test track wetting to be 
accomplished more efficiently; (2) minimizing ABS performance 
variability since the tires would not be previously subject to the high 
speed stopping distance tests on a high coefficient of friction 
surface; and (3) minimizing vehicle transfers for those manufacturers 
that use a different test site for their low coefficient of friction 
tests.
    After reviewing the petitions, NHTSA has decided to amend the 
performance test sequence by placing both braking-in-a-curve tests 
immediately after the burnish. The agency believes that conducting the 
braking-in-a-curve tests at the beginning of the test sequence 
simplifies the procedure and reduces the testing burden without 
compromising safety. The agency has specified the GVWR loading 
condition first because it coincides with the GVWR/LLVW sequence of the 
other stopping performance tests. This decision is also supported by 
the fact that performance variability due to tire wear and flat-
spotting will be minimized if the GVWR test runs are conducted first, 
since wheel lock is more likely to occur in the lightly-loaded 
condition.

B. Brake Adjustment During Test Sequence

    AAMA, HDBMC, Midland-Grau, and Rockwell International petitioned 
NHTSA to permit manual brake adjustments to be made after each part of 
the test sequence in Standard No. 121. The petitioners are concerned 
about the potential for over-adjustment and the impact on the 
subsequent tests in the sequence, during testing with automatic brake 
adjusters. Standard No. 121 currently requires that air-braked vehicles 
be equipped with automatic brake adjusters. The standard allows three 
manual adjustments, at the manufacturer's recommended intervals, during 
the burnish sequence, but does not allow subsequent adjustments during 
the testing itself.
    NHTSA agrees with the petitioners that there is a potential for 
over-adjustment by automatic brake adjusters during a series of full 
treadle brake applications, as is required for the braking-in-a-curve 
tests. The agency also believes that it is important to specify 
precisely where in the test sequence the manual adjustments are 
allowed, since this enhances uniformity of the test procedures. The 
agency nevertheless believes that adjusting the brakes as frequently as 
after each test sequence is inappropriate, because it would be less 
representative of real world braking conditions.
    Based on the above considerations, NHTSA has decided to amend the 
test sequence in Standard No. 121 by allowing some adjustment during 
testing. It is allowing two manual brake adjustments for truck tractors 
- the first at the end of the braking-in-a-curve tests and the second 
at the end of the GVWR parking brake test. It is also allowing one 
manual brake adjustment for single unit trucks and buses, at the end of 
the GVWR parking brake test. The agency believes that allowing a 
limited number of additional adjustments during testing accommodates 
the petitioners' concerns, while preserving a well- defined test 
procedure that properly accounts for the newly adopted test procedures.
    NHTSA believes that there is no need to allow additional brake 
adjustments in the test procedure for Standard No. 105 for hydraulic-
braked heavy vehicles, since the brake test procedure currently 
specifies four burnishes (one burnish and three reburnishes) and a 
brake adjustment after each burnish. Moreover, hydraulic-braked 
vehicles are not subject to the braking-in-a-curve test.

C. Final Brake Inspection in Test Sequence

    HDBMC and Rockwell International petitioned NHTSA to delete the 
final brake inspection requirement that is specified at the end of the 
stopping sequence in Table I of Standard No. 121. They claimed that 
there are no stated requirements necessary to satisfy the results of 
this inspection, and that the condition of the adjusters has little 
significance to the brake adjusters condition after real world 
service.
    NHTSA disagrees with the petitioners' claims that the final brake 
inspection provision is unnecessary. The agency notes that Standard No. 
121 was amended to include the final brake inspection as part of the 
amendments for the rulemaking on automatic brake adjusters. This issue 
has never been included in any of the notices for the heavy vehicle ABS 
rulemaking. As a result, the agency cannot delete the requirement 
without giving the public an opportunity to comment on the issue. 
Moreover, the agency disagrees with the petitioners that there are no 
stated requirements by which a manufacturer can ensure that its vehicle 
complies with this inspection. Paragraph S5.9, Final Inspection, 
specifies that the inspection is conducted to determine the condition 
of adjustment and for the brake indicator display, in accordance with 
S5.1.8 and S5.2.2 (i.e., brake adjustment within the limits recommended 
by the vehicle manufacturer). Based on these considerations, the agency 
has decided to deny the petitioners' request to delete the provision 
regarding the final brake inspection.

V. Braking-In-A-Curve Test

A. General Considerations

    Navistar requested that the agency eliminate the braking-in-a-curve 
test for ABS-equipped truck tractors. That company stated that such a 
test is redundant to the provision requiring ABS because the test would 
not cause any changes to the ABS equipment mandated by the ABS 
equipment requirement.
    NHTSA disagrees with Navistar's claim that the braking-in-a-curve 
performance test is redundant. As explained in the ABS final rule, the 
braking-in-a-curve test provides an important check of ABS performance. 
Merely having the ABS definition does not ensure that an antilock 
system will provide an acceptable level of performance. The test serves 
to evaluate the basic performance of an antilock system. The agency 
notes that the industry, through the Motor Vehicle Safety Research 
Advisory Committee (MVSRAC), has previously endorsed and recommended to 
the agency essentially the same dynamic performance test that is 
contained in the ABS final rule. The agency further notes that Navistar 
provided no support for its claim that the braking-in-a-curve 
performance requirement for truck tractors is redundant. Based on the 
above considerations, the agency has decided to deny Navistar's request 
to delete the braking-in-a-curve test for truck tractors equipped with 
antilock systems.
    ATA requested that the agency apply the braking-in-a-curve 
performance requirements to single unit vehicles and trailers. ATA also 
requested that the agency consider making the requirements less design-
restrictive by permitting, for an interim period, the option of meeting 
either the equipment requirement or the performance requirement.
    While NHTSA agrees with ATA's goal of having a performance test for 
all heavy duty vehicles and not just for tractors, the agency believes 
that it is premature to do so at this time.
    Thus, NHTSA has decided to deny ATA's requests to apply the 
braking-in-a-curve test to single unit vehicles and trailers at this 
time. In the ABS final rule, the agency discussed in detail the reasons 
for including a performance test for truck tractors. (60 FR 13230-
13232) One of those reasons was that extensive truck tractor testing 
conducted by the 

[[Page 63969]]
agency and the industry indicated that the braking-in-a-curve test on a 
low mu surface is an objective, repeatable, and practicable procedure 
for evaluating a heavy vehicle's antilock braking system. However, for 
other heavy vehicles, the agency decided not to apply the braking-in-a-
curve test at that time due to the need to conduct additional testing 
to ensure that these vehicles could be safely tested to the braking-in-
a-curve maneuver. NHTSA is currently planning vehicle research to 
develop such a procedure for other vehicles and, should the research be 
successful, will consider adding performance tests for these vehicles 
to the standard.
    As explained in the final rule, NHTSA regards the braking-in-a-
curve requirement as a complement to the ABS equipment requirement, and 
not as an alternative to it. (60 FR 13231) The braking-in-a-curve test 
alone can neither evaluate the overall effectiveness of ABS nor ensure 
the use of a closed-loop system. Such an evaluation would require an 
array of performance tests such as split mu tests, surface transition 
tests, and stopping distance performance tests. However, as indicated 
above, the braking-in-a-curve test is an objective, repeatable, and 
practicable procedure for evaluating the performance of a vehicle's 
ABS, and will be used by the agency to complement the ABS equipment 
requirement. Based on these considerations, the agency has decided to 
deny ATA's request to allow vehicle manufacturers the option of 
complying either with the equipment requirement or with the braking-in-
a-curve requirement.

B. Type of Brake Application

    In the ABS final rule, NHTSA decided to specify that a driver 
conducting the braking-in-a-curve test must make a full treadle 
application, i.e., apply the brake at a rate sufficient to reach a 
pressure of 100 psi within 0.2 seconds, in at least one of the treadle 
valve's output circuits. The agency believed that these values properly 
represent full brake applications in terms of both the rate of 
application and level of output pressure. (60 FR 13234) This brake 
application is intended to evaluate worst case braking applications in 
an aggressive or ``hard'' stop.
    AAMA, Allied Signal, HDBMC, and Midland-Grau petitioned NHTSA to 
change the definition of full-treadle brake application to allow 
treadle pressure of 60 psi in 0.2 seconds, or maximum treadle travel in 
0.2 seconds. The petitioners claim that some pneumatic systems do not 
achieve 100 psi in 0.2 seconds, but that all systems can achieve 60 psi 
in that time. In support of its claim, Midland-Grau submitted data from 
testing performed on different antilock systems installed on various 
vehicles. The test data show that with the vehicles in the loaded 
condition, the full-treadle brake application pressures at the treadle 
valve were not consistently able to achieve 100 psi in 0.2 seconds. 
However, they were all able to achieve at least 85 psi within 0.2 
seconds.
    Based on NHTSA's analysis of the test data submitted by Midland-
Grau, the agency has decided to amend the definition for ``full treadle 
brake application'' to mean a brake application in which the treadle 
pressure reaches 85 psi within 0.2 seconds * * * '' The agency agrees 
with the petitioners that not all pneumatic systems would have been 
able to achieve a treadle valve output pressure of 100 psi within 0.2 
seconds and that such a high threshold is not necessary to represent an 
aggressive stop. Midland-Grau's data further indicate that the ABS 
would activate at brake chamber pressures below 60 psi on most heavy 
vehicles in the loaded condition on a test surface with a peak friction 
coefficient (PFC) 0.5. However, there are some systems that would need 
at least 60 psi at the brake chamber within 0.2 seconds to ensure 
sufficient air pressure availability for effective ABS control.
    NHTSA has also decided to modify the definition for ``full-treadle 
brake application'' to include a reference to maximum treadle travel 
within 0.2 seconds. By ``maximum treadle travel,'' the agency means the 
distance that the treadle moves, from its position when no force is 
applied to its position when the treadle reaches a full stop. Allowing 
such an alternative is consistent with the agency's intent to require a 
brake application that simulates emergency braking. Moreover, this 
alternative may facilitate the introduction of certain future 
technologies such as electronic braking for which the pressure/time 
relationship at the treadle valve is not applicable.
    Jenflo stated in its petition that NHTSA did not specify a duration 
for the full-treadle brake application. NHTSA agrees that such a 
duration should be specified to avoid misinterpretation of the brake 
application requirement. Accordingly, the agency has decided to amend 
S5.3.6.1 of Standard 121 to read as follows: ``using a full-treadle 
brake application for the duration of the stop, stop the vehicle * * 
*.'' (emphasis added)

C. Number of Test Stops for Certification

    In the ABS final rule, NHTSA decided that requiring compliance with 
the braking-in-a-curve requirements during three consecutive stops is 
appropriate. The agency noted that specifying three consecutive full 
treadle test stops is consistent with both NHTSA's own testing at its 
Vehicle Research and Test Center (VRTC) and its testing in conjunction 
with the motor vehicle industry through the MVSRAC ABS Task Force. The 
agency further noted that because the ABS automatically modulates the 
brakes, using full treadle brake applications to test an ABS- equipped 
vehicle in the braking-in-a-curve maneuver requires less driver skill 
than using a driver-best-effort modulated brake application in the 
stopping distance performance tests. The agency further noted that the 
braking-in-a-curve test is easier to perform than the stopping distance 
test because it is not coupled with a stopping distance requirement. 
Therefore, NHTSA decided not to adopt the AAMA recommendation in the 
NPRM that manufacturers should be given the option of complying in only 
three of ten stops. Adopting that recommendation would have made the 
braking-in-a-curve requirement unreasonably lenient.
    AlliedSignal, Rockwell WABCO, HDBMC, AAMA, and Navistar petitioned 
the agency to allow truck tractors to be regarded as complying with the 
braking-in-a-curve test if they make three successful test runs out of 
six attempts. The petitioners claimed that additional test runs should 
be permitted given that some variability may be caused by the driver's 
performance of braking and steering while conducting these stops. They 
further stated that all of the stopping distance tests of Standard No. 
105, Standard No. 121, and Standard No. 135 recognize the significance 
of driver-best-effort variability by prescribing that just one of six 
attempts need to be successful to satisfy the requirement.
    NHTSA believes that treating three successful runs out of six 
attempts as demonstrating compliance would not provide a sufficiently 
stringent test for antilock brake systems, whose technology has 
demonstrated remarkably consistent performance during vehicle testing 
conducted by the agency and by the motor vehicle industry. As the 
agency stated in the final rule, it is unlikely that driver influences 
will result in significant variability, since the driver does not have 
to modulate the brake pedal to 

[[Page 63970]]
reduce wheel lockup and achieve the best stopping distance performance. 
(60 FR 13234) Nevertheless, since there may be some minor variability 
in the test driver's performance, the agency has decided to provide 
that compliance with the braking-in-a-curve test is demonstrated if a 
vehicle has three successful test runs out of four attempts. NHTSA 
believes that this number of test runs, which allows one failed test 
run, is appropriate for an antilock system tested to a braking-in-a-
curve maneuver.

D. Initial Brake Temperature

    In the March 1995 final rules, NHTSA concluded that an initial 
brake temperature range of between 150  deg.F and 200  deg.F is more 
appropriate than the proposed temperature range of 250  deg.F to 300 
deg.F. The agency determined that testing using the 150  deg.F to 200 
deg.F temperature range is more repeatable and results in less 
variation between test runs, compared to testing conducted at an 
initial brake temperature of 250  deg.F to 300  deg.F, particularly for 
the emergency brake stops.
    Ferodo petitioned the agency to change the initial brake 
temperature to between 100  deg.F and 200  deg.F, claiming that this is 
a more practicable range.
    NHTSA continues to believe that the initial brake temperature range 
of between 150  deg.F-200  deg.F is appropriate. It appears that Ferodo 
is not aware that broadening the initial brake temperature range makes 
the requirements more stringent, since the vehicle would have to comply 
with the requirements at any point within the specified range. The 
consensus of the comments received to the ABS and stopping distance 
NPRMs was that the agency should maintain the 150  deg.F-200  deg.F 
temperature range. In addition, the agency's vehicle research reached a 
similar conclusion. (60 FR 13235) Based on the above considerations, 
the agency has decided to deny Ferodo's petition to broaden the initial 
brake temperature to the range of 100  deg.F to 200  deg.F.

VI. Stopping Distance Performance

A. Stopping Distance Requirements for School Buses

    AAMA and HDBMC petitioned the agency to allow manufacturers the 
option of certifying hydraulic-braked school buses to either the 
existing standard or the new standard with ABS, between now and March 
1, 1999. They stated that, by being given such an option, manufacturers 
would have the incentive to offer ABS on hydraulic-braked school buses 
prior to 1999, and the vehicles would have to meet the more stringent 
second effectiveness test. HDBMC also petitioned the agency to 
immediately delete the first effectiveness test for school buses with a 
GVWR greater than 10,000 pounds.
    NHTSA agrees with the petitioners' request to allow the option of 
meeting the new requirements, including the ABS requirements, prior to 
March 1, 1999. This amendment will facilitate the introduction of ABS 
equipped school buses. Nevertheless, the agency does not agree with 
HDBMC's request to immediately delete the first effectiveness test, 
since deleting this requirement prior to a vehicle being equipped with 
ABS might decrease the braking performance of school buses. NHTSA has 
modified S5.1.1(c) of Standard No. 105 to allow school bus 
manufacturers the option of certifying that their vehicles comply with 
the new requirements, beginning 30 days after this final rule is 
published.

B. Test Surface Specification

    In the stopping distance final rule, NHTSA concluded that a PFC of 
0.9 represents a typical dry surface and will not be a significant 
source of variability in the stopping distance tests. (60 FR 13289, 
13290) The agency's conclusion was based on the industry-government 
cooperative testing to evaluate the effect of fluctuations of PFC on 
vehicle stopping performance.8 Testing indicates that the expected 
minor variability of a high coefficient of friction surface appears to 
have a negligible impact on vehicle stopping distance performance. This 
testing led the agency to conclude that any variability in the stopping 
performance on a high coefficient of friction surface is more likely 
due to variation in the vehicle's performance than test surface 
variability. The agency further stated that a test surface 
specification of PFC 1.0 would result in practicability problems for 
the agency, since it would have problems finding such a surface and 
conducting compliance testing on such a surface.

     8  Public Files Docket PF88-01, MVSRAC ABS Task Force, 
Round Robin No. 1.
---------------------------------------------------------------------------

    Navistar petitioned NHTSA to specify a PFC of 1.0 instead of 0.9 
for the high coefficient of friction surface on which the stopping 
distance performance tests are to be conducted. The petitioner claimed 
that the specification of PFC 0.9 will cause industry to incur costs 
for expensive equipment, maintenance, delays in testing and 
redeployment of scarce resources without any demonstrable safety 
improvement.
    NHTSA has decided to continue to specify a PFC of 0.9 for high 
coefficient of friction surfaces, for the reasons set forth in the 
final rule. The agency notes that Navistar provided no additional 
information calling into question the agency's earlier conclusion that 
a test surface specification of PFC 1.0 would result in practicability 
problems for the agency. The agency therefore has decided to deny 
Navistar's petition.
    AAMA petitioned the agency to allow the PFC of the curved test 
surface for the braking-in-a-curve test to be measured by the American 
Society for Testing and Materials (ASTM) trailer on a straight section 
of the curved test surface. Since the ASTM Method E1337-90 procedure 
specifies a straight line measurement, the agency agrees that measuring 
PFC on a curved road might introduce variability in the measurement as 
a result of lateral forces present at the tire. NHTSA therefore has 
decided to amend Standard No. 121 to allow the PFC of the 500-foot 
radius curved test surface to be measured by the ASTM skid trailer on a 
straight section of the test surface.
    ATA requested that the agency amend S5.3.6.1 to specify that the 
ASTM Method E1337-90 be run either on a wet surface without further 
water delivery or on a dry surface with water delivery.
    NHTSA believes that such an amendment about the test surface is not 
necessary. The agency's skid trailer measurements taken at VRTC show a 
negligible difference (i.e., less than 0.05) for PFC measurements for a 
surface that is ``double wetted'' as compared with an already wet 
surface. This is the same data variability that VRTC obtains from the 
skid trailer measurements of a wetted surface when one type of wetting 
is used. Therefore, if a wet test surface is wetted again just prior to 
skid trailer testing, the level of stringency of the test would be 
essentially the same as that for a ``single wetting'' condition.

C. Wheel Lockup Restrictions

    AlliedSignal, AAMA, HDBMC, and Midland-Grau petitioned NHTSA to 
clarify the wording in S5.3.1 and S5.7.1 of Standard No. 121 to 
explicitly state that ``unlimited wheel lockup is allowed during 
partial failure stops,'' as is stated in S6.10.2(e) of Standard No. 
105.
    NHTSA has decided that it is appropriate to modify the regulatory 
language in S5.7.1 of Standard No. 121 to explicitly allow unlimited 
wheel lockup during emergency brake stops. The agency emphasizes that 
this amendment serves merely to make it clear that unlimited wheel 
lockup is allowed during emergency brake system performance tests. 
While the agency intends to allow unlimited wheel lockup during 
emergency brake stops, it does not intend to allow such unlimited wheel 
lockup for service brake stops in 

[[Page 63971]]
S5.3.1 of Standard No. 121. NHTSA notes that this is only a 
clarification and does not change the requirements that were adopted in 
the March 1995 final rules.
D. Burnish Procedure
    On May 15, 1995, NHTSA issued a notice that terminated rulemaking 
to amend Standard No. 105 and Standard No. 121 with respect to the 
burnish procedures for medium and heavy vehicles. (60 FR 25880) The 
agency determined that it would be unnecessary to extend the period 
during which a manufacturer may choose between two burnish procedures. 
The agency reasoned that its decision was appropriate because 
manufacturers have been certifying compliance to the brake standards, 
based on the ``new'' more representative burnish procedure, since 
September 1994.
    In response to the March 1995 final rules, Navistar petitioned the 
agency to allow, indefinitely, the option of using either the old or 
the new burnish procedure.
    As explained in the May 1995 termination notice, the new burnish 
procedure is currently in effect. Therefore, the issue of allowing the 
option of using the old procedure is moot.
E. Definition of Nonsteerable Axle
    In the stopping distance final rule, NHTSA stated that wheel lockup 
is permitted at certain wheels, including ``any wheel on a nonsteerable 
axle other than the two rearmost nonliftable, nonsteerable axles * * *, 
for any duration * * *.'' (see paragraph S5.3.1(a))
    AAMA requested the agency to make it clear that a nonsteerable axle 
is an axle that does not steer by means of a driver-controlled 
mechanism, and that a self-steering axle would be considered a 
nonsteerable axle.
    NHTSA considers a self-steering axle to be a nonsteerable axle in 
this context, since such an axle is not under the control of the 
driver. The pertinent criterion is that an axle is only considered 
``steerable'' for purposes of this requirement, if the steerability of 
the wheels on that axle is controlled by the steering wheel of the 
vehicle. Since a self-steering axle is not under the control of the 
driver's steering wheel, it is not considered to be steerable.
VII. ABS Malfunction Indicator Lamps
A. In-Cab Malfunction Lamp for Trailer ABS
    In the final rule, NHTSA decided to require lamps in the cab of 
truck tractors to indicate any malfunction with the ABS of any towed 
vehicles. (60 FR 13244, 13245) The agency also required trailers to 
supply trailer ABS malfunction signals to the tractor. This requirement 
is essentially the same as the one proposed prior to the March 1995 
final rule.
    ATA petitioned the agency to delete the provision requiring in-cab 
indication of trailer ABS malfunctions. That organization claimed both 
in its comments to the NPRM and in its petition for reconsideration 
that such a lamp is unnecessary. It also argued that such a requirement 
needlessly complicates the electrical system of the tractor and the 
electrical connector arrangement between tractors and trailers.
    NHTSA disagrees with ATA that the in-cab trailer malfunction lamp 
is unnecessary. Studies have shown that an in-cab malfunction lamp is a 
more effective means of making the driver aware of an ABS malfunction, 
compared with an external malfunction lamp on the trailer.9 The 
agency also disagrees with ATA's statement that having two malfunction 
indicators unreasonably complicates the electrical systems in 
combination vehicles. In their comments on the NPRM, several brake and 
vehicle manufacturers stated that it was appropriate to have two 
indicators. For instance, Midland-Grau strongly opposed having a single 
malfunction indicator, claiming that having a single lamp would make it 
difficult to identify which vehicle had a malfunction without using 
separate diagnostic equipment. Since this issue has been addressed in 
detail in previous notices, and since ATA has not submitted any 
additional data to substantiate its claim, the agency has decided to 
deny ATA's request to delete the in-cab malfunction lamp for the 
trailer ABS.

    \9\ ``An In-Service Evaluation of the Performance, Reliability, 
Maintainability, and Durability of Antilock Braking Systems for 
Semitrailers,'' U.S. Department of Transportation/ NHTSA Report No. 
DOT HS 808 059, October 1993.
---------------------------------------------------------------------------

B. Trailer-Mounted ABS Malfunction Indicator
    In the final rule, NHTSA decided to require an external ABS 
malfunction lamp on trailers and dollies for the eight-year period 
during which some non-ABS-equipped tractors will be towing ABS-equipped 
trailers. (60 FR 13244, 13245) The requirement specified that the 
external lamp ``be visible within the driver's forward field of view 
through rearview mirrors.''
    ATA and UPS petitioned the agency to delete the requirements for an 
external trailer-mounted malfunction lamp. They claimed that the 
external malfunction lamp will lead to less safety because drivers will 
be looking in their mirrors during braking to see whether the ABS lamp 
is functioning, instead of looking at traffic conditions ahead of their 
vehicle.
    NHTSA continues to believe that it is appropriate to require an 
external malfunction lamp on trailers and dollies for the eight-year 
period during which some non-ABS-equipped tractors will be towing ABS-
equipped trailers. The external malfunction lamp will indicate trailer 
ABS malfunctions to the driver of a non-ABS tractor and will also 
assist Federal and State inspectors in determining the operational 
status of a trailer's antilock system. NHTSA disagrees with ATA's claim 
that the external malfunction lamp would create a less safe condition 
for drivers. The agency anticipates that most drivers will look through 
their mirrors to check the lamp infrequently, and only when the vehicle 
is stationary or the road ahead is clear. The agency therefore denies 
the petitions from ATA and UPS to delete the trailer-mounted ABS 
malfunction lamp.
    Midland-Grau and TTMA petitioned the agency to delete the 
requirement in S5.2.3.3 that the external indicator on a trailer be 
visible from the driver's seating position ``through the rearview 
mirrors.'' Midland-Grau stated that since the truck tractor 
manufacturers cannot control where the external lamp would be located, 
requiring that the lamp be visible from the cab of the truck tractor is 
unreasonable. TTMA stated that since trailer manufacturers have no 
responsibility for the mirrors, requiring the ABS malfunction lamp on 
dollies and trailers to be visible ``through the rearview mirrors'' is 
not appropriate. They also stated that there is no good, practical 
location for such a lamp on a dolly.
    Even though NHTSA believes that the external trailer malfunction 
lamp is appropriate, the agency agrees with Midland-Grau and TTMA that 
it is inappropriate to specify a location requirement for the external 
malfunction lamp that is based on what can be seen in a truck tractor's 
rearview mirror. Compliance with such a requirement would depend on 
factors that are not fully controlled by the trailer manufacturer. 
Rearview visibility of the ABS external malfunction lamp could vary 
based on truck tractor design and its aerodynamic fairings, the field 
of view provided by the rearview mirrors, and on the location of the 
lamp. Accordingly, the agency has decided to delete the requirement in 
S5.2.3.3 for rearview mirror visibility of the lamp on trailers and 
dollies.

[[Page 63972]]

    TTMA requested that if the agency retains the requirement for an 
external malfunction lamp on the trailer, then the location of the 
lamp, its color, and its intensity should be specified in Standard No. 
108, Lamps, reflective devices, and associated equipment.
    NHTSA emphasizes that it is important for the driver to see the 
trailer mounted malfunction lamp from his or her driving position. 
Therefore, the agency is issuing, simultaneously with this final rule, 
an NPRM that proposes a lamp location on the trailer and the dolly, but 
without stating any visibility requirements with reference to the 
tractor. The agency agrees with TTMA that it is appropriate to propose 
the location, color, and intensity of the trailer and dolly ABS 
external malfunction lamp. Specifically, the agency is proposing a 
location for the external ABS malfunction indicator on trailers, which 
is similar to the location proposed by the agency when it was 
considering requiring a low pressure warning lamp on trailers (55 FR 
4453, February 8, 1995).
    ATA and UPS petitioned the agency to only require that the ABS 
check lamp be visible for visual inspection during a walk-around of a 
vehicle.
    NHTSA believes that only requiring a lamp for visual inspection 
during a vehicle walk-around is insufficient because current designs 
would require more than one person to conduct the inspection, if the 
trailer is powered through the stop lamp circuit. One person would have 
to apply the brake pedal to provide ABS power to the trailer, and 
another would need to be outside the vehicle to view the ABS lamp, if 
it is located somewhere on the trailer's chassis.

C. Activation Protocol for Malfunction Indicators

    In the final rule, NHTSA decided to require the malfunction 
indicator lamp to activate when a problem exists and not activate when 
the system is functioning properly. (60 FR 13246) Under this 
requirement, the indicator lamp is required to provide a continuous 
indication until a function check of the ABS is completed. Under that 
format, the ABS malfunction lamp extinguishes after a function check, 
and before the vehicle is driven. The agency explained that this ABS 
malfunction lamp format, together with the requirement that the system 
stores malfunctions until the next key-on, is necessary to enable 
Federal and State inspectors to determine the operational status of an 
ABS without moving the vehicle. In support of its decision, the agency 
noted that this activation pattern is consistent with the one for light 
vehicle ABS and the one adopted by the Economic Commission for Europe 
(ECE).
    Navistar petitioned NHTSA to allow the vehicle to be in motion at 
low vehicle speed during an ABS system check so that the sensor check 
could be included before the lamp extinguishes. Navistar stated that 
the benefits of a sensor check outweigh the convenience for use by 
Federal or State inspectors.
    As explained in the final rule, NHTSA believes that the requirement 
that the system store malfunctions until the next key-on is necessary 
to enable Federal and State inspectors to determine the operational 
status of an ABS without moving the vehicle. On March 10, 1995, the 
Federal Highway Administration (FHWA) published a notice of intent to 
initiate rulemaking addressing requirements for motor carriers to 
maintain the ABS on those vehicles that are subject to NHTSA's final 
rule. These requirements could include inspecting the vehicle to 
determine whether ABS is operational. Navistar's request to allow the 
vehicle to be in motion before the lamp extinguishes would impede 
FHWA's inspection process to determine the operational status of ABS. 
The agency therefore has decided to deny Navistar's petition to amend 
the malfunction lamp protocol to allow the lamp to stay lit until the 
vehicle is driven.
    AlliedSignal and TTMA requested that the check of lamp function on 
the external trailer ABS malfunction lamp would only activate when 
power is supplied to the ABS and the vehicle is stationary. They stated 
that such a requirement would prevent the ABS lamp from cycling on and 
off whenever power is supplied or with every brake application in cases 
where the trailer ABS is being powered through the stop lamp circuit.
    NHTSA agrees with the petitioners that such a requirement reduces 
potential distractions to the driver or to drivers of other vehicles 
caused by the lamp cycling on and off with every brake application. The 
agency notes that this modification retains the requirement's primary 
purpose, which is to indicate an ABS malfunction to the driver or to 
Federal and State inspection personnel. The agency has therefore 
decided to amend paragraph S5.2.3.3 to specify that the check of lamp 
function will activate the trailer ABS malfunction lamp, whenever power 
is supplied to the ABS and there is an absence of wheel speed (i.e., 
that the vehicle is stationary).
    TTMA stated that the final rule does not address the operation of 
the ABS malfunction lamp in the event of a total loss of electrical 
power. That organization requested that the agency explicitly state 
that neither the external trailer lamp nor the in-cab lamp is required 
to be activated if there is a total loss of electrical power to the 
trailer.
    A total loss of power causes the control unit to be incapable of 
sending a malfunction signal to the indicator lamp, since the control 
unit for an electronic ABS requires electrical power for operation. 
NHTSA notes that no vehicle system is capable of indicating a warning 
or malfunction in the event of a total loss of electrical power. The 
agency therefore believes that there is no need to specify regulatory 
language about the operation of the ABS malfunction lamp in the event 
of a total loss of electrical power.

D. Signal Storage

    In the final rule, NHTSA decided to require that the ABS indicator 
lamp system be capable of storing information regarding any malfunction 
that existed when the ignition was last turned to the ``off'' position 
or in the case of towed vehicles, when power was last received by the 
ABS. (60 FR 13246, 13247) The agency explained that the malfunction 
storage requirement is necessary to ensure that relief drivers and 
Federal and State inspectors are advised about any malfunctions in a 
vehicle's ABS without having to move the vehicle.
    Rockwell WABCO, Midland-Grau, AAMA, TTMA, and ATA requested that 
the agency define a pre-existing malfunction as a malfunction that 
existed when the ignition switch was last turned to the ``off'' 
position. These petitioners argued that such a definition is necessary 
to clarify that malfunctions that no longer exist are to be cleared and 
do not need to be indicated.
    After reviewing the petitions, NHTSA had decided to amend S5.3.3(b) 
of Standard No. 105, and S5.1.6.2 (a) and (b) and S5.2.3.2 of Standard 
No. 121 to clarify that a pre-existing malfunction is a malfunction 
that existed when the ignition switch was last turned to the ``off'' 
position. The agency never intended to require the indication of 
malfunctions that have been corrected but still remain in the long-term 
memory of the electronic control unit.

E. ABS Failed System Requirements

    In the final rule, NHTSA decided to revise Standard No. 121 to 
prohibit any change in brake timing in the event of ABS malfunctions 
that affect the generation or transmission of response or control 
signals. The agency explained that this modification will ensure that 
the brake system reverts to normal 

[[Page 63973]]
braking without antilock control, in the event of such a malfunction in 
the antilock system.
    AlliedSignal, HDBMC, and Midland-Grau petitioned the agency to 
amend S5.5.1 to require each vehicle to meet the emergency brake 
stopping requirements but not the service brake, actuation and release 
timing requirements. The petitioners are concerned about the potential 
for noncompliance that is not within the control of known antilock 
brake systems.
    NHTSA believes that it is important that a heavy vehicle's brake 
system revert to normal braking without antilock control, in the event 
of an ABS malfunction that affects the generation or transmission of 
response or control signals in any part of the antilock system. The 
agency believes that it would be inappropriate to allow brake 
performance to degrade to the level of the emergency braking 
performance requirements when a typical ABS malfunction exists. The 
service brakes of a vehicle with a malfunctioning ABS should provide a 
level of braking performance that is not substantially different from 
the service brake performance with the ABS operational. This is 
necessary so that the resulting braking performance will not surprise a 
driver when the ABS malfunctions. Based on the above considerations, 
the agency has decided to deny the petitions to amend the performance 
requirements for a vehicle with a failed antilock system.

VIII. Power Source

A. Separate Powering for Trailer ABS

    In the final rule, NHTSA decided to require full time powering for 
the trailer ABSs as well as requiring that the towing vehicle have a 
corresponding separate circuit. (60 FR 13248-13250) The agency 
explained that this requirement provides the strongest possible source 
of electrical power from the tractor to ensure the functioning of the 
ECU, the modulators, and a continuous malfunction indication whenever a 
malfunction exists.
    AAMA, Midland-Grau, and TTMA requested the agency to make it clear 
that the phrase, ``separate electrical circuits, specifically provided 
to power the antilock system,'' is not intended to require that a 
circuit be exclusively utilized by the towed vehicle ABS. AAMA and 
Midland-Grau want the agency to allow other uses for this circuit, such 
as interior van trailer lights and multiplexing applications. ATA 
asserted that the requirement for a separate circuit is redundant and 
costly. ATA subsequently requested the agency in a September 6, 1995 
letter to interpret the requirement for a separate electrical circuit.
    NHTSA has decided to deny the request to permit other uses for the 
separate ABS circuit. As emphasized in the final rule, based on the 
best data available to the agency, NHTSA determined that it is 
necessary for the ABS on towed vehicles to receive full-time power 
through a circuit that is exclusively used by the towed vehicle ABS, so 
as to reduce the possibility of the ABS being inoperative due to lack 
of power. Throughout the rulemaking, the agency has intended that a 
towed vehicle antilock system be powered through a separate electrical 
circuit that is specifically provided to power the antilock system.
    NHTSA based that decision on the results of its field evaluation of 
the durability, reliability, and maintainability of trailer ABS systems 
(as reported in DOT Report No. HS 808 059). That report noted that each 
of the three electrical powering methods that employed a separate 
circuit (e.g., the Cole-Hersee 13-pin connector, the separate 6-pin 
connector, and the separate ISO connector) was superior to the stoplamp 
powering approach. Each of these separate powering approaches used 
completely dedicated electrical circuits, which included separate, 
fully dedicated positive and ground wires, to power the trailer ABS 
ECUs. Based on the existing data, the agency therefore believes that 
both positive and ground wires separate from those now provided for 
other uses are necessary to adequately power trailer ABS systems. The 
agency has no technical basis for concluding that circuits that share 
the existing ground provided by the currently-used SAE J560 connector 
would provide power as well as a fully separate circuit, and therefore 
has no basis to conclude that such a powering scheme would be adequate.
    NHTSA is aware of extensive industry efforts in various Society of 
Automotive Engineers' (SAE) technical committees to establish 
performance standards for electrical systems used to power tractor and 
trailer ABS systems which include objective performance test 
procedures, measurement criteria, and, in some cases, target 
performance levels. If those efforts result in the development of 
consensus standards that would ensure high quality tractor and trailer 
electrical systems that could be demonstrated to adequately supply 
electrical power to trailer ABS systems, the agency would consider 
alternative means of satisfying the safety need for adequate trailer 
ABS powering, other than the one which currently available data 
indicate is necessary.
    NHTSA has been asked whether the rule allows the use of the SAE 
J560 connector. The agency reiterates the point it made in the final 
rule, i.e, that it is leaving to industry the decision as to which 
design approach is used to implement the performance requirement that 
trailer ABS be supplied power through a separate circuit and that a 
means of signaling trailer ABS malfunctions to the tractor also be 
provided. SAE J560 standard both specifies the physical connector and 
standardizes the uses for each of the seven pins. Thus, the connector, 
if it is configured as specified in the J560 standard could not be 
used, because there is, at most, one pin available for new uses, and up 
to three new ones could be required. However, if the industry chooses 
to reconfigure the presently-used SAE J560 connector hardware in such a 
manner as to meet the requirements for a separate trailer ABS powering 
circuit (both positive and ground) and malfunction signaling, then that 
solution would be permitted. The agency notes that such a solution 
would require multiplexing of some circuits, in order to free up enough 
pins for ABS power.
    NHTSA agrees with TTMA's concern that ``if the auxiliary circuit is 
used to provide full-time power to ABS, then there would be potential 
for inadvertently powering the auxiliary devices, due to human error, 
if a manual switch is left on * * *'' Such an inadvertent powering of 
an auxiliary device that uses the same power circuit as the ABS could 
result in a low voltage condition at the electronic control unit of the 
ABS, thus making the ABS inoperative. Also, the suggestion that the 
trailer ABS powering circuit could be shared with other electrical 
devices and still be adequate if power to those devices were 
automatically switched off (except when the vehicle is stationary), 
lacks an objective basis to gauge whether such an automatic means would 
be fail-safe. If the automatic means failed, the trailer ABS systems 
could have insufficient power. The agency therefore considers this 
approach to providing separate power to trailer ABSs to be inadequate.

B. ABS Malfunction Signal Circuit and Ground

    In the final rule, NHTSA specified detailed requirements about the 
capabilities of the electrical circuits. Among other things, paragraph 
S5.2.3.2 requires each non-towing trailer to have the means for 
connection of the antilock 

[[Page 63974]]
malfunction signal circuit and ground, at the front of the trailer.
    AAMA and Midland-Grau petitioned the agency to delete the word 
``circuit'' in the phrase ``malfunction signal circuit and ground'' in 
S5.2.3.2, claiming that it could be interpreted as requiring a separate 
circuit with dedicated power and ground wires.
    After reviewing the petitions, NHTSA has decided to amend paragraph 
S5.2.3.2 to delete the words ``and ground'' from the phrase 
``malfunction signal circuit and ground.'' The agency notes that it did 
not intend to require a dedicated circuit for the ABS malfunction 
signal circuit on trailers. The agency agrees with the petitioners that 
since a ``circuit'' is defined as an electrical path having both a 
power source and a ground, the present language could be confusing, and 
that the language should be changed to avoid being misinterpreted.
    TTMA requested that the agency amend S5.1.6.2(a) and S5.2.3.2, 
which require that the vehicle be equipped with an ``electrical circuit 
that is capable of signaling a malfunction.'' The petitioner stated 
that the ABS, not the electrical circuit, should be required to signal 
a malfunction.
    NHTSA agrees that TTMA's requested language is more precise than 
the wording in the final rule's regulatory text, and amends the 
regulatory language accordingly.
    AAMA, Midland-Grau, and TTMA petitioned the agency to amend 
S5.1.6.2(c), which currently requires that a truck or truck tractor 
designed to tow another vehicle have an electrical circuit that is 
capable of ``transmitting'' information about a malfunction. The 
petitioners requested that the word ``transmitting'' be changed to 
``receiving.''
    NHTSA believes that it would be inappropriate to substitute the 
word ``receiving'' for ``transmitting'' since this electrical circuit 
both transmits and receives information. When towing a trailer, a 
tractor transmits the malfunction information that it receives from the 
trailer's ABS to the ABS malfunction indicator lamp in the cab of the 
tractor or the truck. Even though the agency has decided not to change 
the word ``transmitting'' in S5.1.6.2 to ``receiving,'' it has decided 
to clarify the provision's wording.
    In addition to the changes specifically addressed by the petitions, 
NHTSA has decided to reword all three ABS malfunction circuit and 
indicator provisions (S5.1.6.2, S5.2.3.2, and S5.2.3.3) to clarify them 
and make them more consistent in form and wording to each other and to 
the other parts of the standard.
    In particular:
    (a) The new 10 S5.1.6.2(a) is written as a general 
requirement.

    \10\ ``New'' refers to changes made in today's document; ``old'' 
refers to the regulatory text adopted in the March 10, 1995 final 
rule.
---------------------------------------------------------------------------

    (b) The old S5.1.6.2(a) and S5.1.6.2(b) has been combined into one 
paragraph.
    (c) The old S5.1.6.2(c) has been renumbered S5.1.6.2(b) and has 
been reworded to delete references to trailer failures in a tractor 
requirement.
    (d) The new S5.2.3.2 no longer references a ``key switch'' or an 
in-cab ABS malfunction lamp, because those items are not present on 
trailers.
    (e) The new S5.2.3.3 now includes requirements for memory and check 
of lamp functions.

C. Tractor Trailer ABS Interface Connector

    AAMA petitioned the agency to specify the electrical connector, SAE 
J2272, Tractor Trailer Interface Connector, stating that ``the industry 
will not be able to converge to a single solution in the absence of 
regulatory direction.'' AAMA claimed that without regulatory direction, 
the end users could prevent an industry approach from being 
implemented, which would result in a proliferation, rather than needed 
deproliferation, in connector strategies. In its petition for 
reconsideration, TTMA supported the J2272 connector. However, in a 
later submission to the docket, that organization withdrew its support 
of that connector. TTMA now supports a separate connector, but does not 
favor any one in particular. ATA supports the current seven-pin 
connector.
    NHTSA is aware that the industry is considering several options for 
powering trailer antilock systems and that it is having a difficult 
time reaching a consensus. The agency agrees that the SAE J2272 
connector is one potentially permissible approach that should be given 
full consideration by the industry. However, the agency is also aware 
that the 7-pin configuration of the SAE J2272 connector might not allow 
the industry to have a one-connector solution in the long term, even if 
some of its pins are multiplexed. It is NHTSA's belief that the 
industry understands and can best respond to the future electrical 
powering needs for trailers, such as antilock braking systems, 
electronic braking systems, and satellite tracking and communications 
network. The agency believes that obtaining compatibility provides 
sufficient incentive for the industry to reach a consensus to 
standardize on a connector to comply with the full-time power and in-
cab malfunction lamp requirements without the need for an electrical 
connector equipment requirement mandated by NHTSA. AMA, ATA, TTMA, and 
brake component manufacturers have been meeting under the auspices of 
SAE in an effort to reach consensus on the connector issue. These 
meetings indicate that all parties have placed forward and backward 
compatibility as an important issue for the industry to resolve and 
reach consensus. Based on these considerations, the agency has decided 
to deny the petition from AAMA to specify the SAE J2272 Tractor Trailer 
Interface Connector (or any other specific connector) as required 
equipment for tractors and trailers.

IX. Applicability of Amendments and Leadtime

A. Hydraulic-Braked Vehicles

    In the final rule, NHTSA stated that a March 1999 compliance date 
for installing antilock brake systems on hydraulic-braked single-unit 
trucks and buses provides sufficient time for vehicle manufacturers and 
ABS manufacturers to complete the development and testing of these 
systems. (60 FR 13250-13251) It noted that some Japanese and European 
manufacturers are currently marketing ABS for medium and heavy 
hydraulic-braked vehicles and that brake manufacturers expressed 
confidence that such antilock systems will be available in the United 
States.
    In its petition, ATA expressed concern that NHTSA was requiring 
hydraulic-braked heavy vehicles to be equipped with antilock brake 
systems, even though that organization claimed that such systems are 
not currently commercially available for heavy vehicles sold in the 
United States. ATA further stated that ``different concepts are 
necessary for hydraulic ABS on medium and heavy vehicles because of 
dissimilarities'' between the braking systems of hydraulic-braked light 
vehicles and hydraulic-braked medium/heavy vehicles. Given these 
concerns, ATA and UPS petitioned the agency to postpone the compliance 
date for hydraulic-braked vehicles, claiming that no antilock systems 
are available for these vehicles and such systems, when they are 
available, would need time to be tested. The petitioners urged the 
agency to postpone the compliance date for these vehicles until 2 years 
after the technology is readily available. Further, UPS reiterated its 
request for a three-year phase-in scheme of 20 percent/50 

[[Page 63975]]
percent/100 percent for the entire ABS applicability requirement.
    NHTSA continues to believe that it is appropriate to require that 
medium and heavy hydraulic-braked vehicles be equipped with ABS, 
starting in March 1999. Two leading manufacturers of medium and heavy 
hydraulic vehicles, Freightliner and Navistar, have announced that they 
will offer the AlliedSignal hydraulic antilock brake system on their 
hydraulic-braked vehicles in 1996. Freightliner will offer ABS as an 
option on its Class 5-8 hydraulic Business Class models, while Navistar 
will offer hydraulic ABS as standard equipment on all its medium truck 
chassis, including the 4000 Series.11 Moreover, in its comments to 
the April 1994 SNPRM, Freightliner stated that the March 1, 1999 ABS 
compliance date for hydraulic-braked heavy vehicles is realistic and 
appropriate, but urged the agency to continue to monitor manufacturers' 
progress and be willing to act on short notice, if necessary, to 
provide additional lead time.

     11  ``Medium-Duty ABS,'' Pickup and Delivery September 
1995
---------------------------------------------------------------------------

    NHTSA disagrees with ATA's claim that there are significant 
differences between ABS on hydraulic-braked light vehicles compared 
with medium and heavy vehicles. AlliedSignal, a manufacturer of both 
air-braked and hydraulic-braked ABS, stated in its comments to the 
September 1993 NPRM that the hydraulic- braked ABS technology that will 
be used on heavy vehicles is the same as the technology now used on 
passenger cars and other light vehicles, and that the application of 
hydraulic-braked ABS on heavy vehicles ``should not present significant 
technical risk.'' That company also explicitly stated that ``components 
are identical or nearly identical to that used in the passenger car and 
light truck applications.'' It added that ``the wheel speed sensors are 
the same technology as used in light vehicle applications, and in fact 
are the same as that planned for air-braked vehicles. The electronic 
control unit utilizes the same components as light vehicles * * * and 
is planned to be the same as that supplied by our AlliedSignal Truck 
Brake System Company for air braked vehicle applications.'' 
AlliedSignal concluded their comments to the NPRM by stating that as a 
supplier of ABS for hydraulic-braked vehicles, the requirements can be 
reliably achieved with proven technology within the suggested time 
frame.
    Such similarities are also present when comparing ABS on air braked 
vehicles and hydraulic-braked vehicles. In the September 1995 Pickup & 
Delivery article, a representative of AlliedSignal stated that--

    There's quite a few similarities in complexity [between 
hydraulic and air braked ABS]. For example, the means of sensing 
wheel speed is basically identical. There's a wheel speed sensor 
that's used to check the speed of each wheel. You also have an ECU 
which monitors those wheel speeds and identifies if they are 
remaining constant or there are differentials from one side to 
another or front to rear.

    ATA also disagreed with NHTSA statements, claiming that ABS will 
not be required on European trucks until after NHTSA's requirement 
takes effect.
    NHTSA believes that ATA's claim is based on a misinterpretation of 
the European type approval system as compared with the United States' 
self-certification system. The agency is aware that there are new 
European requirements pending for hydraulic-braked medium and heavy 
vehicles equipped with ABS, with the first compliance date of January 
1999. In Europe, newly produced vehicles with old type-approvals can 
use their old brake system design for a period of time after the 
compliance dates when ABS will be required on new type-approved 
vehicles. Therefore, these vehicles can continue to be built and sold 
without ABS, even after the European compliance dates, which begin in 
January 1999. When a manufacturer redesigns a vehicle, however, the new 
design has to be typed-approved, and therefore would be required to 
comply with the new ABS requirements. Hence, ATA is technically correct 
that some hydraulic-braked heavy vehicles built for the European market 
will be allowed to be built without ABS even after the compliance date 
for the United States requirements. However, other European market 
vehicles with hydraulic brakes will have to have ABS before their 
United States counterparts. Due to the differences between the type 
approval and self-certification processes, there is no way to 
completely synchronize the introduction of ABS on hydraulic- braked 
heavy vehicles in the United States and in Europe, and there is no 
reason to delay introduction in the United States until after all 
European vehicles are required to have it.
    Based on the above comments from manufacturers and the positive 
experience in other countries with ABS-equipped hydraulic-braked 
vehicles, NHTSA has determined that requiring hydraulic-braked vehicles 
to be equipped with ABS is practicable and appropriate. The agency 
continues to believe that four years is sufficient leadtime for vehicle 
manufacturers to develop and test these antilock systems, given that 
ABS technology has already been introduced on light vehicles equipped 
with hydraulic braking systems. Therefore, the agency has decided to 
deny ATA's petition to extend the compliance date for equipping 
hydraulic-braked vehicles with ABS.
    AM General petitioned the agency to change the compliance date for 
equipping hydraulic-braked vehicles with ABS from March 1, 1999, to 
September 1, 1999. It claimed that the company would face complications 
in making such a major mid-year change.
    NHTSA notes that vehicles produced on or after the specified 
compliance dates must comply with the new requirements. This also means 
that a vehicle manufacturer can comply with the new brake requirements 
before the compliance date of the new requirements. Hence, if AM 
General finds it difficult to comply with the March 1, 1999 compliance 
date because of the mid-year timing of the date, then it has the option 
of complying with the new requirements prior to that date, such as on 
September 1, 1998.
    AM General petitioned the agency to specify a timetable for 
monitoring and reviewing the technical status and viability of 
commercially available hydraulic antilock systems.
    NHTSA currently has no plans for specifying a formal timetable for 
monitoring and reviewing the technical status of hydraulic-braked ABS 
for heavy vehicles. Nevertheless, the agency plans to monitor this 
development closely and could modify the implementation schedule if 
development of antilock systems for hydraulic-braked vehicles faced 
unexpected development problems. As stated above, vehicle and brake 
manufacturers indicate that they will have hydraulic antilock systems 
commercially available in 1996. The agency has provided a leadtime of 
four years to ensure that manufacturers will have sufficient time to 
develop and test antilock systems for hydraulic-braked heavy vehicles. 
The agency believes that the fleets and users, the ABS manufacturers, 
and the vehicle manufacturers can work together to lay out a timetable 
for the industry so that antilock systems for these heavy vehicles are 
ready for commercial use by March 1, 1999.

B. Class 3 Vehicles

    AM General petitioned that the ABS requirements not apply to 
vehicles with GVWRs between 10,001 and 14,000 pounds (Class 3 trucks). 
It argued that 

[[Page 63976]]
since many of these vehicles are derived from light vehicles, and given 
its belief that the effectiveness of ABS on light vehicles is open to 
debate, the industry should be given the opportunity to review and 
consider comments on equipping Class 3 vehicles with ABS.
    NHTSA has previously stated that excluding vehicles of certain 
weight classes between 10,000 and 26,000 pounds GVWR would create an 
uneven application of the ABS requirements and could result in an 
inconsistent regulatory framework that would not provide safety 
benefits to all vehicles. The results of the accident data analysis 
that examined the effectiveness of ABS on light vehicles showed that 
there was a net positive safety benefit from equipping vans, sport 
utilities, and light trucks with ABS. Since many Class 3 vehicles are 
derived from these light trucks, the agency anticipates that Class 3 
vehicles will also experience safety benefits from being equipped with 
ABS. The agency therefore disagrees with AM General's conclusion and 
has decided to deny its petition requesting that Class 3 vehicles be 
excluded from applicability to the ABS requirements because of the lack 
of demonstrated effectiveness of ABS on passenger cars.

C. Four-Wheel Drive Vehicles

    AM General also requested that the ABS requirement not apply to 
four-wheel drive vehicles. The company stated that it has had 
difficulty getting an ABS supplier to develop a system for its Hummer 
vehicle because of the vehicle's full-time 4WD, torque-biasing 
differentials on both axles, and low volume production. AM General 
believes that the issue of four-wheel drive ABS has been overlooked and 
needs to be addressed openly.
    NHTSA believes that it is appropriate to apply the ABS requirements 
to four-wheel drive vehicles, since such vehicles can and do lose 
control during braking. Moreover, the agency is aware of ABS 
applications on current vehicles equipped with full-time four-wheel 
drive or with all-wheel drive, and believes that the ABS technology, to 
accomplish an ABS installation on AM General's Hummer vehicle, is 
readily available. Therefore, the agency has decided to deny AM 
General's petition requesting that four-wheel drive vehicles be 
excluded from being equipped with ABS.

D. Trailers and Dollies

    UPS petitioned the agency to implement ABS on air-braked vehicles 
by using a three-year phase-in scheme of 20 percent/50 percent/100 
percent for trailers and dollies. That company requested that in 1998, 
20 percent of trailers and dollies be required to have ABS; in 1999, 50 
percent be required to have ABS; and in 2000, 100 percent be required 
to have ABS. UPS claims that it faces critical problems regarding 
reliability and cost to meet the current effective dates.
    NHTSA believes that such a protracted delay in the implementation 
of ABS on trailers and dollies is unnecessary, given the current state 
of development of ABS for these vehicles and given that 2S/1M and 
tandem control configurations on semi-trailers and dollies are being 
allowed. The agency further notes that no ABS or trailer manufacturer 
expressed concerns about the agency's timetable or ABS reliability. 
Moreover, in the final rule, the agency discussed in detail the issues 
that ATA and UPS raised about reliability of ABS on heavy vehicles. 
NHTSA concluded that ABSs are reliable and that maintenance costs 
associated with ABS are neither excessive nor unreasonable compared to 
other maintenance costs. The agency further stated that these costs 
will not be significantly reduced if the implementation dates of this 
rule are further delayed.

X. Miscellaneous

A. National Uniformity

    ATA petitioned the agency to clarify that States may not impose 
compliance dates that differ from NHTSA's rules. That organization 
specifically requested NHTSA to ``confirm * * * that any attempt under 
State law to impose a retroactive ABS mandate would frustrate the 
significant Federal statutory purpose and, therefore, is not 
permitted.''
    NHTSA notes that the statute (formerly known as the ``National 
Traffic and Motor Vehicle Safety Act of 1966'') clearly addresses the 
issue of preemption at 49 USC 30103(b). That provision states that when 
a Federal motor vehicle safety standard is in effect, a State generally 
may only prescribe an identical standard.

B. Publish Complete Regulatory Texts and Compliance Test Procedures

    AAMA, HDBMC, and Midland-Grau requested that the agency immediately 
publish complete and updated versions of Standard No. 105 and Standard 
No. 121.
    NHTSA agrees that there should be complete and updated versions of 
Standard No. 105 and Standard No. 121, showing all the amendments made 
by the ABS and Stopping Distance rulemakings. Such changes are 
generally reflected in the Code of Federal Regulations published 
annually by the National Archives and Records Administration. The 
agency believes that the publication of updated versions of Standard 
No. 105 and Standard No. 121 would be helpful to the regulated 
industry. Since the agency's first priority is to issue the substantive 
rules, it has issued today's notice first. The agency anticipates 
publishing the updated Standards in 1996.
    AAMA, AlliedSignal, HDBMC, and Midland-Grau petitioned the agency 
to provide the compliance test procedures for Standard 121, TP-121, 
within 60 days after April 10, 1995.
    NHTSA notes that these compliance test procedures are currently 
under development by the agency and will be made available in the near 
future.

C. Costs

    ATA claimed that NHTSA's cost estimate for ABS ``are low by roughly 
a factor of two.'' That organization stated that fleets are getting 
bids on ABS equipment and actual quotes are running at almost $2,000 
per tractor and $1,400 per trailer.
    NHTSA disagrees with ATA that the agency's cost estimates for ABS 
are low by ``a factor of two.'' The agency conducted an in-depth study 
of heavy vehicle ABS cost, and the findings are reported in a final 
report, ``Incremental Cost, Weight, and Leadtime Impacts of Requiring 
Heavy Truck Tractor/Trailer ABS,'' published in June 1994. This study 
is based on an annual production volume of 100,000 ABS units. Hence, it 
is to be expected that the current prices that ATA is quoting would be 
higher than those provided in the agency's study, considering that 
current annual production of ABS units is under 10,000 units.

D. Corrections to Standard No. 101 and Standard No. 105

    NHTSA has revised Table 2 of Standard No. 101, Controls and 
Displays, to correct several of the identifying symbols in Column 4, 
which were inadvertently changed in the regulatory text of the final 
rule. The attached Table 2 has been revised to include the original 
identifying symbols in Column 4.
    NHTSA has also corrected Table II of Standard No. 105 to reflect 
correct positioning of footnote references.

XI. Rulemaking Analyses and Notices

A. Executive Order 12866 and DOT Regulatory Policies and Procedures

    This notice was reviewed under Executive Order 12866. NHTSA has 

[[Page 63977]]
    considered the impacts of this rulemaking action and determined that it 
is ``significant'' within the meaning of the Department of 
Transportation's regulatory policies and procedures. In connection with 
the March 1995 final rules, the agency prepared a Final Economic 
Assessment (FEA) describing the economic and other effects of this 
rulemaking action. Summary discussions of those effects were provided 
in the ABS final rule. The amendments in this final rule do not make 
those effects any more stringent, and in some respects make it easier 
for a manufacturer to comply with them. For persons wishing to examine 
the full analysis, a copy is in the docket.

B. Regulatory Flexibility Act

    NHTSA has also considered the effects of both this final rule or 
the original final rule under the Regulatory Flexibility Act. I hereby 
certify that it will not have a significant economic impact on a 
substantial number of small entities. Accordingly, the agency has not 
prepared a final regulatory flexibility analysis.
    The primary cost effect of the requirements in this final rule or 
in the original final rules will be on manufacturers of heavy vehicles 
which are generally large businesses. However, final stage 
manufacturers are generally small businesses. A detailed discussion 
about the anticipated economic impact on these businesses is provided 
in the FEA.

C. National Environmental Policy Act

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

D. Executive Order 12612 (Federalism)

    NHTSA has analyzed this action under the principles and criteria in 
Executive Order 12612. The agency has determined that this notice does 
not have sufficient Federalism implications to warrant the preparation 
of a Federalism Assessment. No State laws will be affected.

E. Civil Justice Reform

    This final rule does 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 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.

List of Subjects in 49 CFR Part 571

    Imports, Motor vehicle safety, Motor vehicles, Rubber and rubber 
products, Tires.
    In consideration of the foregoing, the agency is amending Standard 
No. 101, Controls and Displays, Standard No. 105, Hydraulic Brake 
Systems and Standard No. 121, Air Brake Systems, in Title 49 of the 
Code of Federal Regulations at Part 571 as follows:

PART 571--[AMENDED]

    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. In Sec. 571.101, Table 2 is revised to appear as follows: 
Sec. 571.101 Standard No. 101; Controls and Displays.
* * * * *

BILLING CODE 4910-59-P

[[Page 63978]]
[GRAPHIC][TIFF OMITTED]TR13DE95.001



BILLING CODE 4910-59-C

[[Page 63979]]

    2. Section 571.105 is amended by revising the definition of 
``Directly controlled wheel'' in S4; by revising S5.1.1(c), S5.3.3(b); 
S5.5.1, S7, and S7.5 to read as follows:
Sec. 571.105  Standard No. 105, Hydraulic Brake Systems
* * * * *
    S4.* * *
    Directly Controlled Wheel means a wheel for which the degree of 
rotational wheel slip is sensed, either at that wheel or on the axle 
shaft for that wheel and corresponding signals are transmitted to one 
or more modulators that adjust the brake actuating forces at that 
wheel. Each modulator may also adjust the brake actuating forces at 
other wheels that are on the same axle or in the same axle set in 
response to the same signal or signals.
* * * * *
    S5.1.1* * *
    (c) The service brakes shall be capable of stopping each vehicle 
with a GVWR greater than 10,000 pounds in two effectiveness tests 
within the distances and from the speeds specified in S5.1.1.2 and 
S5.1.1.3. Each school bus with a GVWR greater than 10,000 pounds 
manufactured after January 12, 1996 and before March 1, 1999 and which 
is equipped with an antilock brake system may comply with paragraph 
S5.1.1.2 and S5.5.1 rather than the first effectiveness test, as 
specified in S5.1.1.1. Each school bus with a GVWR greater than 10,000 
pounds manufactured on or after March 1, 1999 shall be capable of 
meeting the requirements of S5.1.1 through S5.1.5, under the conditions 
prescribed in S6, when tested according to the procedures and in the 
sequence set forth in S7.
* * * * *
    S5.3.3* * *
    (b) For vehicles with a GVWR greater than 10,000 pounds, each 
message about the existence of a malfunction, as described in 
S5.3.1(c), shall be stored in the antilock brake system after the 
ignition switch is turned to the ``off'' position and the indicator 
lamp shall be automatically reactivated when the ignition switch is 
again turned to the ``on'' position. The indicator lamp shall also be 
activated as a check of lamp function whenever the ignition is turned 
to the ``on'' (run) position. The indicator lamp shall be deactivated 
at the end of the check of lamp function unless there is a malfunction 
or a message about a malfunction that existed when the key switch was 
last turned to the ``off'' position.
* * * * *
    S5.5.1 Each vehicle with a GVWR greater than 10,000 pounds, except 
for any vehicle that has a speed attainable in 2 miles of not more than 
33 mph, shall be equipped with an antilock brake system that directly 
controls the wheels of at least one front axle and the wheels of at 
least one rear axle of the vehicle. On each vehicle with a GVWR greater 
than 10,000 pounds but not greater than 12,000 pounds, the antilock 
brake system may also directly control the wheels of the drive axle by 
means of a single sensor in the drive line. Wheels on other axles of 
the vehicle may be indirectly controlled by the antilock brake system.
* * * * *
    S7. Test procedures and sequence. Each vehicle shall be capable of 
meeting all the applicable requirements of S5 when tested according to 
the procedures and in the sequence set forth below, without replacing 
any brake system part or making any adjustments to the brake system 
other than as permitted in the burnish and reburnish procedures and in 
S7.9 and S7.10. (For vehicles only having to meet the requirements of 
S5.1.1, S5.1.2 and S5.1.3 in section S5.1, the applicable test 
procedures and sequence are S7.1, S7.2, S7.4, S7.5, S7.8, S7.9, S7.10 
and S7.18. However, at the option of the manufacturer, the following 
test procedures and sequence may be conducted: S7.1, S7.2, S7.3, S7.4, 
S7.5, S7.6, S7.7 S7.8, S7.9, S7.10 and S7.18. The choice of this option 
shall not be construed as adding to the requirements specified in 
S5.1.2 and S5.1.3.) Automatic adjusters must remain activated at all 
times. A vehicle shall be deemed to comply with the stopping distance 
requirements of S5.1 if at least one of the stops at each speed and 
load specified in each of S7.3, S7.5, S7.8, S7.9, S7.10, S7.15 and 
S7.17 (check stops) is made within a stopping distance that does not 
exceed the corresponding distance specified in Table II. When the 
transmission selector control is required to be in neutral for a 
deceleration, a stop or snub shall be obtained by the following 
procedures:
    (a) Exceed the test speed by 4 to 8 mph;
    (b) close the throttle and coast in gear to approximately 2 mph 
above the test speed;
    (c) shift to neutral; and
    (d) when the test speed is reached, apply the service brakes.
* * * * *
    S7.5 Service brake system-second effectiveness test. Repeat S7.3, 
except for vehicles with a GVWR greater than 10,000 lbs. Then, for 
vehicles with a GVWR of 10,000 pounds or less, make four stops from 80 
mph if the speed attainable in 2 miles is not less 84 mph.
* * * * *
    3. Section 571.121 is amended by revising the definitions of 
``Directly Controlled Wheel'' and ``Full-treadle brake application'' in 
S4; by adding the definition for ``Maximum treadle travel'' in S4; and 
by revising S5.1.6.2, S5.2.3.2, S5.2.3.3, S5.3.1, S5.3.6, S5.3.6.1, and 
S5.7.1 to read as follows:
Sec. 571.121  Standard No. 121; Air Brake Systems.

* * * * *
    S4.* * *
    Directly Controlled Wheel means a wheel for which the degree of 
rotational wheel slip is sensed, either at that wheel or on the axle 
shaft for that wheel and corresponding signals are transmitted to one 
or more modulators that adjust the brake actuating forces at that 
wheel. Each modulator may also adjust the brake actuating forces at 
other wheels that are on the same axle or in the same axle set in 
response to the same signal or signals.
* * * * *
    Full-treadle brake application means a brake application in which 
the treadle valve pressure in any of the valve's output circuits 
reaches 85 psi within 0.2 seconds after the application is initiated, 
or in which maximum treadle travel is achieved within 0.2 seconds after 
the application is initiated.
* * * * *
    Maximum treadle travel means the distance that the treadle moves 
from its position when no force is applied to its position when the 
treadle reaches a full stop.
* * * * *
    S5.1.6.2  Antilock Malfunction Signal.
    (a) Each truck tractor manufactured on or after March 1, 1997 and 
each single unit vehicle manufactured on or after March 1, 1998 shall 
be equipped with an indicator lamp, mounted in front of and in clear 
view of the driver, which is activated whenever there is a malfunction 
that affects the generation or transmission of response or control 
signals in the vehicle's antilock brake system. The indicator lamp 
shall remain activated as long as such a malfunction exists, whenever 
the ignition (start) switch is in the ``on'' (run) position, whether or 
not the engine is running. Each message about the existence of such a 
malfunction shall be stored in the antilock brake system after the 
ignition switch is turned to the ``off'' position and automatically 
reactivated when the ignition switch is again turned to the ``on'' 
position. The indicator lamp shall also be activated as a check of lamp 
function whenever the ignition is turned to the ``on'' or ``run'' 
position. 

[[Page 63980]]

The indicator lamp shall be deactivated at the end of the check of lamp 
function unless there is a malfunction or a message about a malfunction 
that existed when the key switch was last turned to the ``off'' 
position.
    (b) Each truck tractor manufactured on or after March 1, 1997, and 
each single unit vehicle manufactured on or after March 1, 1998 that is 
equipped to tow another air-braked vehicle, shall be equipped with an 
electrical circuit that is capable of transmitting a malfunction signal 
from the antilock brake system(s) on one or more towed vehicle(s) 
(e.g., trailer(s) and dolly(ies)) to the trailer ABS malfunction lamp 
in the cab of the towing vehicle, and shall have the means for 
connection of this electrical circuit to the towed vehicle. Each such 
truck tractor and single unit vehicle shall also be equipped with an 
indicator lamp, separate from the lamp required in S5.1.6.2(a), mounted 
in front of and in clear view of the driver, which is activated 
whenever the malfunction signal circuit described above receives a 
signal indicating an ABS malfunction on one or more towed vehicle(s). 
The indicator lamp shall remain activated as long as an ABS malfunction 
signal from one or more towed vehicle(s) is present, whenever the 
ignition (start) switch is in the ``on'' (run) position, whether or not 
the engine is running. The indicator lamp shall also be activated as a 
check of lamp function whenever the ignition is turned to the ``on'' or 
``run'' position. The indicator lamp shall be deactivated at the end of 
the check of lamp function unless a trailer ABS malfunction signal is 
present.
    (c) [Reserved]
* * * * *
    S5.2.3.2  Antilock Malfunction Signal. Each trailer (including a 
trailer converter dolly) manufactured on or after March 1, 1998 that is 
equipped with an antilock brake system shall be equipped with an 
electrical circuit that is capable of signalling a malfunction in the 
trailer's antilock brake system, and shall have the means for 
connection of this antilock brake system malfunction signal circuit to 
the towing vehicle. The electrical circuit need not be separate or 
dedicated exclusively to this malfunction signaling function. The 
signal shall be present whenever there is a malfunction that affects 
the generation or transmission of response or control signals in the 
trailer's antilock brake system. The signal shall remain present as 
long as the malfunction exists, whenever power is supplied to the 
antilock brake system. Each message about the existence of such a 
malfunction shall be stored in the antilock brake system whenever power 
is no longer supplied to the system, and the malfunction signal shall 
be automatically reactivated whenever power is again supplied to the 
trailer's antilock brake system. In addition, each trailer manufactured 
on or after March 1, 1998, that is designed to tow another air-brake 
equipped trailer shall be capable of transmitting a malfunction signal 
from the antilock brake system(s) of additional trailers in a 
combination by means of its ABS malfunction signal circuit, and shall 
have the means for connection of its ABS malfunction signal circuit to 
the towed vehicle.
    S5.2.3.3  Antilock Malfunction Indicator. In addition to the 
requirements of S5.2.3.2, each trailer (including a trailer converter 
dolly) manufactured on or after March 1, 1998 and before March 1, 2006, 
shall be equipped with an external indicator lamp that is activated 
whenever there is a malfunction that affects the generation or 
transmission of response or control signals in the trailer's antilock 
brake system. The indicator lamp shall remain activated as long as such 
a malfunction exists, whenever power is supplied to the antilock brake 
system. Each message about the existence of such a malfunction shall be 
stored in the antilock brake system whenever power is no longer 
supplied to the system, and the malfunction signal shall be 
automatically reactivated when power is again supplied to the trailer's 
antilock brake system. The indicator lamp shall also be activated as a 
check of lamp function whenever power is supplied to the antilock brake 
system and the vehicle is stationary. The indicator lamp shall be 
deactivated at the end of the check of lamp function unless there is a 
malfunction or a message about a malfunction that existed when power 
was last supplied to the antilock brake system.
* * * * *
    S5.3.1  Stopping distance--trucks and buses. When stopped six times 
for each combination of vehicle type, weight, and speed specified in 
S5.3.1.1, in the sequence specified in Table I, each truck tractor 
manufactured on or after March 1, 1997 and each single unit vehicle 
manufactured on or after March 1, 1998 shall stop at least once in not 
more than the distance specified in Table II, measured from the point 
at which movement of the service brake control begins, without any part 
of the vehicle leaving the roadway, and with wheel lockup permitted 
only as follows:
    (a) At vehicle speeds above 20 mph, any wheel on a nonsteerable 
axle other than the two rearmost nonliftable, nonsteerable axles may 
lock up, for any duration. The wheels on the two rearmost nonliftable, 
nonsteerable axles may lock up according to (b).
    (b) At vehicle speeds above 20 mph, one wheel on any axle or two 
wheels on any tandem may lock up for any duration.
    (c) At vehicle speeds above 20 mph, any wheel not permitted to lock 
in (a) or (b) may lock up repeatedly, with each lockup occurring for a 
duration of one second or less.
    (d) At vehicle speeds of 20 mph or less, any wheel may lock up for 
any duration.
Table I.--Stopping Sequence
    1. Burnish.
    2. Stops on a peak friction coefficient surface of 0.5: (a) With 
the vehicle at gross vehicle weight rating (GVWR), stop the vehicle 
from 30 mph using the service brake, for a truck tractor with a loaded 
unbraked control trailer. (b) With the vehicle at unloaded weight plus 
up to 500 lbs., stop the vehicle from 30 mph using the service brake, 
for a truck tractor.
    3. Manual adjustment of the service brakes allowed for truck 
tractors, within the limits recommended by the vehicle manufacturer.
    4. Other stops with vehicle at GVWR:
    (a) 60 mph service brake stops on a peak friction coefficient 
surface of 0.9, for a truck tractor with a loaded unbraked control 
trailer, or for a single-unit vehicle.
    (b) 60 mph emergency brake stops on a peak friction coefficient of 
0.9, for a single-unit vehicle. Truck tractors are not required to be 
tested in the loaded condition.
    5. Parking brake test with the vehicle loaded to GVWR.
    6. Manual adjustment of the service brakes allowed for truck 
tractors and single-unit vehicles, within the limits recommended by the 
vehicle manufacturer.
    7. Other stops with the vehicle at unloaded weight plus up to 500 
lbs.
    (a) 60 mph service brake stops on a peak friction coefficient 
surface of 0.9, for a truck tractor or for a single-unit vehicle.
    (b) 60 mph emergency brake stops on a peak friction coefficient of 
0.9, for a truck tractor or for a single-unit vehicle.
    8. Parking brake test with the vehicle at unloaded weight plus up 
to 500 lbs.
    9. Final inspection of service brake system for condition of 
adjustment.
    S5.3.6  Stability and Control During Braking-Truck Tractors. When 
stopped four consecutive times for each combination of weight, speed, 
and road conditions specified in S5.3.6.1 and 

[[Page 63981]]
S5.3.6.2, each truck tractor manufactured on or after March 1, 1997 
shall stop at least three times within the 12-foot lane, without any 
part of the vehicle leaving the roadway.
    S5.3.6.1  Using a full-treadle brake application for the duration 
of the stop, stop the vehicle from 30 mph or 75 percent of the maximum 
drive-through speed, whichever is less, on a 500- foot radius curved 
roadway with a wet level surface having a peak friction coefficient of 
0.5 when measured on a straight or curved section of the curved roadway 
using an American Society for Testing and Materials (ASTM) E1136 
standard reference tire, in accordance with ASTM Method E1337-90, at a 
speed of 40 mph, with water delivery.
* * * * *
    S5.7.1  Emergency brake system performance. When stopped six times 
for each combination of weight and speed specified in S5.3.1.1, except 
for a loaded truck tractor with an unbraked control trailer, on a road 
surface having a PFC of 0.9, with a single failure in the service brake 
system of a part designed to contain compressed air or brake fluid 
(except failure of a common valve, manifold, brake fluid housing, or 
brake chamber housing), the vehicle shall stop at least once in not 
more than the distance specified in Column 5 of Table II, measured from 
the point at which movement of the service brake control begins, except 
that a truck-tractor tested at its unloaded vehicle weight plus up to 
500 pounds shall stop at least once in not more than the distance 
specified in Column 6 of Table II. The stop shall be made without any 
part of the vehicle leaving the roadway, and with unlimited wheel 
lockup permitted at any speed.
* * * * *
    Issued on: December 8, 1995.
Ricardo Martinez,
Administrator.
[FR Doc. 95-30375 Filed 12-11-95; 8:45 am]
BILLING CODE 4910-59-P