Federal Motor Vehicle Safety Standards: Heavy Vehicle Antilock Brake System (ABS) Performance Requirement

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. 99-6550]

RIN 2127-AH16

Federal Motor Vehicle Safety Standards: Heavy Vehicle Antilock

Brake System (ABS) Performance Requirement

AGENCY: National Highway Traffic Safety Administration (NHTSA),

Department of Transportation (DOT).

ACTION: Notice of proposed rulemaking.

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SUMMARY: On March 10, 1995, NHTSA published a final rule amending the

hydraulic and air brake standards to require medium and heavy vehicles

to be equipped with antilock brake systems (ABS) to improve the

directional stability and control of these vehicles during braking. We

supplemented the ABS requirements for truck tractors with a braking-in-

a-curve performance test on a low-coefficient of friction surface,

using a full brake application, in both the unloaded (bobtail)

condition and with the tractor loaded to its gross vehicle weight

rating (GVWR) using an unbraked control trailer. The braking-in-a-curve

test was not applied to single-unit trucks or buses or to air-braked

trailers because we had performed only limited testing of ABS-equipped

single-unit vehicles. We stated that we would continue research on

dynamic performance tests for single-unit trucks, buses, and trailers,

and would consider applying performance test requirements to these

vehicles in the future.

The agency is now proposing to apply the braking-in-a-curve dynamic

performance test requirement to single-unit trucks and buses that are

required to be equipped with antilock braking systems. After issuing

the March 1995 final rule, we tested several ABS-equipped single-unit

trucks and buses equipped with both hydraulic and air

[[Page 71378]]

brakes. We tentatively conclude that the test results confirm that the

braking-in-a-curve performance test requirement is practicable for

those vehicles. Adopting this requirement would complement the ABS

equipment requirements and stopping distance requirements. Taken

together, these requirements would improve the ability of the affected

vehicles to stop in a stable and controllable manner.

Dates: Comment closing date: You should submit your comments early

enough to ensure that Docket Management receives them not later than

February 22, 2000.

Addresses: You should mention the docket number of this document in

your comments and submit them in writing to: Docket Management, Room

PL-401, 400 Seventh Street, SW, Washington, DC, 20590.

You may call Docket Management at 202-366-9324. You may visit the

Docket from 10 a.m. to 5 p.m., Monday through Friday.

FOR FURTHER INFORMATION CONTACT:

For non-legal issues, you may call Mr. Jeff Woods, Safety Standards

Engineer, Office of Crash Avoidance Standards, Vehicle Dynamics

Division at (202) 366-2720, and fax him at (202) 493-2739.

For legal issues, you may call: Mr. Otto Matheke, Attorney-Advisor,

Office of the Chief Counsel at (202) 366-2992, and fax him at (202)

366-3820.

You may send mail to both of these officials at National Highway

Traffic Safety Administration, 400 Seventh St., SW, Washington, DC,

20590.

SUPPLEMENTARY INFORMATION:

I. Background

II. Single-Unit Truck & Bus ABS Performance Testing

III. Proposed Braking-in-a-Curve Test for Single-Unit Trucks and

Buses

A. Air-braked Trailers Not Included

B. Testing in the Loaded/GVWR Conditions

C. Road Test Geometry

D. Test Surface

E. Test Speed

F. Type of Brake Application

G. Number of Test Stops

H. Required Performance

I. Lightly-Loaded Test Weight

J. Loaded Test Weight

K. Initial Brake Temperature

L. Transmission Position

M. Test Sequence

N. Special Drive Considerations

IV. Intermediate and Final Stage Manufacturers

V. Benefits

VI. Costs

VII. Compliance Date

VIII. Rulemaking Analyses and Notices

A. EO 12866 and DOT Regulatory Policies and Procedures

B. Regulatory Flexibility Act

C. Federalism

D. National Environmental Policy Act

E. Paperwork Reduction Act

F. Unfunded Mandates

G. Civil Justice Reform

IX. Comments

I. Background

On December 18, 1991, Congress passed the Intermodal Surface

Transportation Efficiency Act (ISTEA or Act), Pub. L. 102-240. Section

4012 of the Act directed the Secretary of Transportation to initiate

rulemaking for improving the braking performance of new commercial

motor vehicles, i.e., those with GVWRs of over 26,000 pounds (lbs.),

including truck tractors, trailers, and dollies. The Act directed that

in that rulemaking, the agency examine antilock brake systems (ABS),

means of improving brake compatibility, and methods of ensuring the

effectiveness of brake timing.

In response to that congressional mandate, we published an advance

notice of proposed rulemaking (ANPRM) on June 8, 1992 announcing our

interest in proposing improvements in the directional stability and

control of heavy vehicles during braking (57 FR 24212). That notice

requested comments on such issues as the occurrence of loss-of-control

crashes; the availability and performance of systems to improve

directional stability and control; anticipated performance

requirements, test procedures, and equipment requirements; diagnostic

equipment to ensure in-use functioning of the systems; and anticipated

costs of such equipment. The notice also requested comments on whether

to include vehicles with GVWRs between 10,000 and 26,000 lbs. in the

rulemaking action.

NHTSA received comments in response to the ANPRM from heavy vehicle

manufacturers and users, brake manufacturers, safety advocacy groups,

trade associations, state entities and individuals. Most agreed that we

should take action to improve the stability and control of heavy

vehicles during braking to reduce the number of loss-of-control

crashes. Commenters also addressed the application of potential

rulemaking to certain vehicles, test procedures, warning and diagnostic

systems, an implementation schedule for the requirements, and the costs

of the hardware.

We next published a notice of proposed rulemaking (NPRM) on

September 28, 1993 (58 FR 50738) to amend Federal Motor Vehicle Safety

Standard (Standard) Nos. 105, Hydraulic brake systems (now titled

Hydraulic and electric brake systems), and 121, Air brake systems, to

require all air-braked and hydraulic-braked vehicles with GVWRs over

10,000 lbs. to be equipped with ABS to improve the lateral stability

and control of these vehicles during braking. The NPRM also proposed

that the ABS requirement be supplemented by a braking-in-a-curve test

on a low coefficient of friction surface using a full brake

application.

We published a final rule requiring ABS on hydraulic and air-braked

medium and heavy vehicles on March 10, 1995 (60 FR 13216) (hereinafter

referred to as the stability and control final rule). The ABS

requirements included a braking-in-a-curve performance test on a low-

coefficient of friction surface for truck tractors only. The test

includes a full brake application in both the unloaded (bobtail)

configuration and with the tractor loaded to its GVWR, the latter using

an unbraked control trailer.

The braking-in-a-curve test was not applied to single-unit trucks,

buses, or air-braked trailers at that time. Our Motor Vehicle Safety

Research Advisory Committee's ABS Task Force had developed the braking-

in-a-curve test procedure only for truck tractors. Since neither the

agency nor the Task Force had included single-unit vehicles in the test

program up to that time, we decided that, in view of the limited

available data with respect to such vehicles and the concerns expressed

by the American Automobile Manufacturers Association and other

commenters about this dynamic performance test, we would apply the

braking-in-a-curve test to truck tractors only. We stated, however,

that we would continue research on dynamic performance tests for

single-unit vehicles and would consider applying performance test

requirements to those vehicles at a future time 1 (see

section II below for a discussion of the testing of single unit trucks

and buses that gave rise to this rulemaking action).

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\1\ The agency published two companion final rules on the same

day, one to reinstate stopping distance requirements for air-braked

medium and heavy vehicles (60 FR 13286) and another to implement

stopping distance requirements for hydraulic-braked medium and heavy

vehicles (60 FR 13297). The cost/benefit information used for the

three final rules was based on NHTSA's Final Economic Assessment,

Final Rules, FMVSS Nos. 105 & 121, Stability and Control During

Braking Requirements and Reinstatement of Stopping Distance

Requirements for Medium and Heavy Vehicles, published in February,

1995.

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II. Single-Unit Truck and Bus ABS Performance Testing

NHTSA conducted ABS testing of single-unit trucks and buses in 1996

and 1997 at our Vehicle Research and Test

[[Page 71379]]

Center (VRTC) in East Liberty, OH 2. Five air-braked

straight trucks and two hydraulic-braked buses, all equipped with ABS,

were used in the tests to aid in determining if the braking-in-a-curve

performance test for tractors could also be applied to single-unit

vehicles. The vehicles were subjected to all the requirements of

Standards No. 105 and No. 121, including the braking-in-a-curve

performance tests.

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\2\ DOT HS 808941, Single Unit Truck and Bus ABS Braking-In-A-

Curve Performance Testing, February 1999.

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The braking-in-a-curve tests were conducted by first finding the

maximum drive-through speed, then determining the maximum brake-through

speed. Maximum drive-through speed is defined in Standard No. 121 as

the fastest constant speed that a vehicle can be driven through at

least 200 feet of curve arc length without departing the lane. Maximum

brake-through speed is defined as the fastest speed at which a full

brake application can be made while the vehicle is in the curve,

without the vehicle departing the lane. Determination of the maximum

brake-through speed provided data on the potential margin of compliance

or non-compliance for the test vehicles. More than four stops for the

braking-in-a-curve test were performed during the loaded and unloaded

tests.

The straight trucks were chassis-cabs without bodies or equipment

that would normally be installed by a second-stage manufacturer. The

vehicles were equipped with ABS systems that met the equipment

requirements of Standard No. 121. In order to simulate the unloaded

condition of completed vehicles, a 2,500 lb load frame was installed on

the chassis cabs. The load frame, which is used to secure ballast to

the vehicle for testing in the loaded condition, includes a built-in

roll bar to protect the test driver in the event of rollover during the

tests. The instrumentation for collecting the test data, and the test

driver, added another estimated 250 pounds to the unloaded vehicle test

weight. Tests were conducted with all fuel tanks and fluid reservoirs

filled to normal capacity.

To test the straight trucks in the loaded condition, we added steel

and/or concrete weights to the load frame so that the total weight of

the vehicles was in accordance with their GVWRs and the axle loads were

in proportion with their GAWRs. For most of the vehicles, the loads

were situated so that the centers of gravity of the loads were 32

inches above the frame. This provided a ballast height which

corresponded to the specification in Standard No. 121 that the control

trailer used for truck tractor road tests have a ballast center of

gravity height not more than 24 inches above the flat bed surface of

the control trailer. The 32-inch load height for single unit trucks is

eight inches higher than for truck tractors to account for the height

from the tractor's frame rails to the top of the control trailer, due

to the fifth wheel coupling arrangement. For two of the vehicles,

however, we conducted additional tests in the fully loaded condition

with the load elevated to the maximum height specified by the

manufacturer in their final-stage manufacturer's guidelines. These two

tests with elevated center of gravity loadings were conducted to give

some indication of the effect center of gravity height has on braking

performance in the braking-in-a-curve test.

The two school buses were equipped with ABS systems that met the

ABS equipment requirements of Standard No. 105 that became effective on

March 1, 1999. Since they were complete vehicles, no load frame or

ballast was added for tests in the unloaded condition. However, the

test instrumentation and driver added approximately 250 pounds to the

unloaded vehicle weight. In addition, all fuel tanks and fluid

reservoirs were filled to normal capacity. The loaded tests on the two

school buses were conducted by placing sand bags on the floor and seats

of each bus such that the total vehicle weight was equal to its GVWR

with the axle load in proportion with the vehicle's GAWR.

The braking-in-a-curve tests were conducted on an asphalt surface

that was coated with Jennite, a driveway sealer, and wetted using a

water truck. A 12-foot-wide lane was marked with the center of the lane

having a 500-foot radius of curvature. The lane was marked with traffic

cones on both sides spaced at 20-foot intervals. The surface had a

cross slope of one percent and approximately zero longitudinal slope.

The peak coefficient of friction (PFC) of the surface during the time

of the testing ranged from 0.34 to 0.41. The effect of the cross slope

was such that the test condition was considered to be worst case, since

all road testing may not be able to be conducted on a completely level

road surface due to variability and water run-off design requirements.

The effect of the lower PFC would also be considered a worst-case test

condition.

In conducting the tests, the driver was instructed to begin the

test in the center of the lane and to steer as necessary to keep the

vehicle within the lane. If any cones were hit, the vehicle was

considered to have gone out of the lane. The maximum drive-through

speed was determined by making passes through the lane at a constant

speed and increasing or decreasing the speed slightly on each

successive pass to determine the maximum speed at which the vehicle

would remain within the lane. Once this speed was determined, two or

three additional passes were made to verify that the speed determined

was the maximum speed at which the vehicle would remain in the lane.

Similarly, the maximum brake-through speed was determined by making

successive stops, increasing the speed gradually each time, to find the

maximum speed at which the vehicle would stay in the lane. For these

stops, the brake was applied as rapidly as possible to a full pressure

application or full travel condition and held until the end of the

stop.

The results of the testing at VRTC confirmed that the braking-in-a-

curve test is practicable, repeatable, and safe for single unit

vehicles. Six of the seven vehicles tested met the performance

requirements now in effect for tractors, i.e., they stayed in the lane

in at least three out of four stops when subjected to maximum braking

at 75 percent of the maximum drive-through speed. In fact, these six

vehicles remained in the lane during all four stops at 75 percent of

the drive-through speed, all with a large margin of compliance.

The two trucks for which elevated center-of-gravity ballast height

comparison tests were conducted showed that the increased height did

not have much effect on the vehicle's performance compared with the

lower, 32-inch ballast center-of-gravity height testing. The test

driver commented that this test condition caused an unsettling feeling

during the testing in the vehicle's roll stability. However, to

observers watching the testing, there were no indications that the

vehicles were nearing rollover, such as lifting of an inside tire.

We note that the one vehicle that did not meet the 75 percent of

drive-through speed requirements was equipped with heavy duty axles

with GAWR ratings of 20,000 pounds for the steer axle and 30,000 pounds

for the single drive axle. Paragraph S3(b) of Standard No. 121 provides

that any vehicle with an axle that has a GAWR of 29,000 pounds or more

is excluded from Standard No. 121. Therefore, this particular vehicle

would not need to comply with the braking-in-a-curve test. If a

manufacturer were to produce this vehicle to comply voluntarily with

Standard No. 121, regardless of the exclusion for axles over 29,000

pounds, additional ABS development would probably be necessary. We note

also that

[[Page 71380]]

while this vehicle did not meet the proposed requirements when tested

in the unloaded condition, it passed the tests in the loaded condition

by staying in the lane in all four of the stops at 75 percent of the

drive-through speed.

III. Proposed Braking-in-a-Curve Test for Single-Unit Trucks and

Buses

Based on the tests conducted at VRTC, NHTSA proposes a braking-in-

a-curve test for single-unit trucks and buses, similar to the stability

and control performance test in effect for air-braked tractors. We

propose slight modifications, however, to allow for the differences

between tractors and single-unit vehicles and to accommodate vehicles

with hydraulic braking systems. Specifics of the proposed test are

provided in the following subsections.

A. Air-Braked Trailers Not Included

NHTSA is not proposing at this time to apply performance test

requirements to air-braked trailers. We have not conducted testing of

trailers since the March 1995 final rules, but may resume research

concerning trailer dynamic performance tests at a later date.

B. Testing in the Loaded/GVWR Conditions

NHTSA proposes that the braking-in-a-curve test be conducted in

both the lightly-loaded vehicle condition and with the vehicle loaded

to GVWR. There are several reasons why we are proposing testing in both

loading conditions. First, this would be consistent with the test

procedure currently in place for tractors. Second, testing in the

fully-loaded and empty conditions was specified in the stability and

control final rule in order to fully evaluate the vehicle's braking

performance at two extreme loading conditions. The intent was to

determine the minimum number of test conditions that would provide a

thorough evaluation of a vehicle's braking system. Third, we determined

that these two loading conditions, evaluated in the single braking-in-

a-curve maneuver, provide a sufficient range of test conditions while

still providing a minimum level of performance testing.

The agency is aware of a discussion in the SAE Truck and Bus

Vehicle Deceleration and Stability Subcommittee that braking-in-a-curve

testing of medium and heavy vehicles is only needed in the lightly-

loaded condition. The discussion, which took place at the 1995 SAE

Truck and Bus Exposition in Winston-Salem, N.C., centered around

testing performed by member organizations of the subcommittee

indicating that vehicles in the lightly-loaded test condition have a

lower margin of compliance than vehicles tested in the loaded

condition.

Our testing at VRTC indicated the following for the seven vehicles

tested with regard to the proposed 75 percent maximum brake-through to

maximum drive-through test requirement: (a) Four vehicles had lower

margins of compliance in the lightly-loaded tests than in the loaded

tests; (b) two vehicles had the same margin of compliance in both the

loaded and lightly-loaded tests; and (c) one vehicle had a higher

margin of compliance in the lightly-loaded test than in the loaded

test. These results indicate that in general, the lightly-loaded test

condition is the most severe test. We note, however, that the margin of

compliance was generally high for most of the vehicles tested. The

intent of testing vehicles in both the lightly-loaded and GVWR

conditions was to simulate the possible braking conditions and

maneuvers likely to be encountered by vehicles operated on public

roads, while minimizing the number of tests that would have to be

conducted to certify compliance. Deleting the loaded-to-GVWR test

condition would eliminate the range of test conditions resulting in a

single, lightly-loaded test. Although we are not proposing to eliminate

testing at GVWR, we welcome comments on this issue.

C. Road Test Geometry

NHTSA proposes the same road test geometry now in effect for

tractors, namely a 12-foot-wide lane with a 500-foot radius measured at

the center of the lane. We consider this geometry to be representative

of an exit ramp with a moderately sharp curve, a type of road that all

vehicles could be expected to encounter at some time. One consideration

in the use of this test geometry for single-unit vehicles is that the

wheelbases of such vehicles can be longer than for tractors or of the

control trailer kingpin-to-axle length. Since most heavy vehicles are

equipped with a non-steering rear axle(s), the path of the rear axle of

a single-unit truck during a slow-speed turning maneuver follows a

smaller radius than the wheels on the front steer axle. The tests

conducted at VRTC, which included testing vehicles with wheelbases

ranging from 148 inches through 311 inches, did not indicate any

problems with the inside wheels on the rear axle(s) running off the

inside of the curve and departing the lane. We believe, therefore, that

the 500-foot radius curve is large enough to avoid that problem during

testing of single-unit vehicles.

D. Test Surface

We propose a test surface having a PFC of 0.5, which is a low

coefficient of friction surface representative of a wet, worn asphalt

roadway. As we noted in the stability and control final rule,

maintaining a test surface of 0.5 PFC may not always be possible.

However, minor variations in the test surface are not expected to have

a major effect on the performance of vehicles in the braking-in-a-curve

test, since that test has no stopping distance requirements. We have

also determined that specifying PFC test surfaces is more appropriate

for both high and low-friction surface testing compared to the older

method of specifying skid numbers. This is especially true for ABS-

equipped vehicles which, during maximum braking, are prevented from

sustained wheel lockup. The testing conducted at VRTC confirmed that

this is the case for the medium and heavy single-unit vehicles tested

and that specifying a PFC of 0.5 is appropriate for the braking-in-a-

curve test.

E. Test Speed

NHTSA proposes a test speed of 75 percent of the maximum drive-

through speed or 30 mph, whichever is lower, for the braking-in-a-curve

test for single unit trucks and buses.

The requirement for testing tractors at the lower value of either

30 mph or 75 percent of the maximum drive-through speed resulted from

the need to have sufficient vehicle speed to adequately evaluate the

performance of an ABS-equipped braking system. The test speed needed to

be limited, however, to ensure that the test procedure could be safely

conducted. In addition, by conducting the maximum drive-through speed

determination before the braking-in-a-curve test, the effects of slight

variability in test surface friction would be minimized since the

drive-through speed would be measured for each combination of test

vehicle and test surface just prior to conducting the braking tests.

All of the single-unit trucks and buses tested at VRTC had maximum

drive-through speeds in both the empty and loaded conditions ranging

between 32 and 37 mph. This range represents the maximum constant speed

that the vehicle can be driven through 200 feet of curve arc (for a

500-foot radius curve) without the driver's losing control and the

vehicle's departing the lane. None of the vehicles was able to

negotiate the curve at 40 mph, which would be the upper limit of the

drive-through speed determination required for a braking strategy

specified as the lower of 30

[[Page 71381]]

mph or 75 percent of maximum drive-through speed. Therefore, these

speeds are sufficiently high to place the vehicles at their performance

limit for cornering under this test condition. Further, conducting a

maximum brake application at 75 percent of this speed is a rigorous

test of ABS performance.

The testing at VRTC also indicated that the test speeds were not so

high as to pose an unreasonable risk to the test drivers or vehicles.

When the vehicles did lose control during the determination of the

maximum drive-through speed, the test drivers were able to regain

control in a short time and bring the vehicle to a safe stop. The test

vehicles were equipped with a roll bar in the event of vehicle rollover

during testing. However, no rollovers occurred nor were there any

indications of near-rollover, although as noted above, the testing with

high-center-of-gravity loadings did result in an unsettling feeling for

the test driver.

F. Type of Brake Application.

NHTSA proposes a brake pedal force of 150 pounds that is to be

achieved within 0.2 seconds from the initial application of force to

the brake control and maintained for the duration of the stop.

We stated in the stability and control final rule that the braking-

in-a-curve test evaluates vehicle stability and control during worst

case braking applications in an aggressive or ``hard'' stop. In that

scenario, full brake applications are more readily repeatable than

``driver best effort'' brake applications. A full treadle brake

application for air-braked tractors is defined in Standard No. 121 as

the output pressure measured at any of the treadle valve output

circuits reaching 85 psi within 0.2 seconds after the application is

initiated, or, as amended in the December 1995 final rule, one in which

maximum treadle travel is achieved within 0.2 seconds after the

application is initiated. Since the actuation of air brakes in single-

unit vehicles is similar to that used in tractors, we consider this

same approach to be valid for single-unit vehicles as well. The tests

at VRTC confirmed that the minor differences in the service braking

systems between tractors and the single-unit vehicles tested were not

found to have an effect on the ability of achieving the 85 psi

application within 0.2 seconds as measured at the treadle valve. We are

aware that, because of the wide variety of single-unit vehicles, there

may be vehicles that would not be able to achieve this application

rate. In those cases, achieving maximum treadle travel within 0.2

seconds would be considered sufficient to define a full brake

application.

Standard No. 105 does not currently include a definition of a full

brake application for medium and heavy vehicles equipped with hydraulic

braking systems. Performance requirements for the first effectiveness

stop for school buses with GVWRs of over 10,000 lbs. and the second and

third effectiveness stops for all vehicles with GVWRs of over 10,000

lbs. do not include specifications for maximum brake pedal force during

these tests. For the five fade and recovery stops that apply to

vehicles with GVWRs of over 10,000 lbs., the maximum permissible pedal

force is 150 lbs. during the first four of these stops. The water

recovery test requirements also include a 150-lbs. maximum pedal force

requirement during the first four stops. These tests do not require

that the maximum pedal force be used nor do they specify an application

rate. The spike stops required for vehicles with GVWRs of less than

10,000 lbs. include a specification for a 200-lb. brake pedal

application within 0.08 seconds, and is representative of a maximum

braking condition such as a ``panic'' stop. However, this high level of

pedal force may make it necessary to use a mechanical actuator to

achieve and maintain the 200-lb. force. Since the purpose of the

proposed braking-in-a-curve test for medium and heavy vehicles is to

evaluate the stability and control during a ``hard'' stop, rather than

specifically a ``panic'' stop, we tentatively conclude that a pedal

force of 150 lbs. is sufficient to perform the braking-in-a-curve

evaluation, without necessitating specialized test equipment. In

addition, since the proposed test surface has a PFC of 0.5, which

represents a slippery road surface, we tentatively conclude that the

150 lbs. of pedal force is sufficient to cause instability and loss of

control in many medium or heavy vehicles that are not equipped with

ABS.

The agency considers the proposed 0.2 seconds for achieving the

150-lbs. brake pedal force to be sufficiently rapid to represent a hard

stop in a medium or heavy vehicle equipped with hydraulic brakes, and

practicable from the standpoint of conducting performance tests on

these type vehicles. While the spike stop requirements for vehicles

under 10,000 lbs. GVWR include achieving the pedal application force

within 0.08 seconds, the heavier brake components typically used in

medium and heavy vehicles equipped with hydraulic brakes may not be

able to be actuated as rapidly as in light vehicles. Also, the 0.08

second application rate for the spike stops in light vehicles is often

achievable only with a mechanical brake pedal actuator. In all of the

braking-in-a-curve tests conducted by VRTC on medium and heavy vehicles

with both hydraulic and air brakes, the test driver applied the brakes

to minimize test complexity. This may also slightly increase the

application time needed compared to a mechanical brake pedal actuator.

NHTSA is not proposing to specify the brake pedal application rate

for medium and heavy vehicles equipped with hydraulic brakes to include

a reference to maximum pedal travel, as is specified for air-braked

vehicles. The brake pedals in hydraulic braking systems do not

typically reach their physical limit of travel during ``hard'' or

``panic'' stops. Therefore, we believe that specifying such a brake

application rate strategy for hydraulic-braked vehicles would be

inappropriate.

G. Number of Test Stops

NHTSA proposes that in 4 consecutive stops, the required

performance must be achieved in at least 3 of those stops.

In the stability and control final rule, we required that tractors

comply with the braking-in-a-curve test requirements during 3

consecutive stops. In response to several petitions for

reconsideration, we amended that requirement in the December 13, 1995

final rule to include one additional stop in which compliance is not

required. Thus, the requirement now is that tractors must comply with

the braking-in-a-curve test requirements in 3 out of 4 consecutive

stops. This allows for minor variability in the performance of the test

driver.

Earlier testing of ABS-equipped tractors showed that the ABS

provided consistent performance in maintaining stability and control

during the braking-in-a-curve test. Although one vehicle could not

comply with the braking-in-a-curve test during the VRTC testing of ABS-

equipped straight trucks and buses, the vehicles that did stay in the

lane during the test were able to do so consistently. We believe,

therefore, that it is appropriate to include that same number of test

stops for straight trucks and buses as we now require for tractors,

namely that during 4 consecutive stops, the required performance must

be met in at least 3 of those stops (see H below).

H. Required Performance

NHTSA proposes to require that the test vehicle remain within a 12-

foot-wide lane during the braking-in-a-curve test.

[[Page 71382]]

We believe that prescribing a 12-foot-wide lane during the braking-

in-a-curve test is an appropriate performance measure for single-unit

trucks and buses. The lane width of 12 feet is representative of a

typical travel lane on a typical U. S. hard-surface road. Therefore, we

tentatively conclude that it is appropriate to require that vehicle

control within a lane of that width be maintainable by a driver during

hard braking.

I. Lightly-Loaded Test Weight

NHTSA proposes that the braking-in-a-curve test in the lightly-

loaded condition be conducted at the curb weight of the vehicle plus up

to 1,500 pounds, including the driver, instrumentation, and roll bar.

As discussed above, the single-unit trucks tested at VRTC were

chassis-cabs which had not been completed by the installation of a body

or other equipment. In order to provide some additional weight to the

chassis-cabs to better simulate an unloaded completed vehicle, a 2,500

pound load frame was bolted directly to the frame rails of each test

vehicle. This load frame was also used to secure ballast for tests

conducted in the loaded condition. As noted above, we are aware of the

discussion in the trucking industry, through the SAE Truck and Bus

Vehicle Deceleration and Stability Subcommittee, as to what suitable

weight should be used for a load frame for testing incomplete vehicles.

We do not propose that any weight figure be specified in the stability

and control requirements for Standard Nos. 105 and 121. We are aware of

the wide variety of bodies and equipment that are installed on chassis-

cabs and the variability in the weight of that equipment. Selection of

one weight for a load frame may be appropriate for one weight class of

vehicle, but not for another. Thus, unlike the vehicles we tested at

VRTC, we do not conduct compliance testing on incomplete vehicles. For

the purposes of compliance testing, we will obtain completed vehicles

and expect to test them at their curb weight, plus an allowance for

test and safety equipment, as discussed below.

The VRTC tests of buses in the unloaded configuration were

performed on completed vehicles, so no additional weight, other than

the driver and instrumentation, was added for the unloaded tests. The

tests were conducted with the buses at curb weight with full fuel

tanks. The combined weight of the test driver and instrumentation was

approximately 250 pounds.

A January 6, 1997 petition for rulemaking submitted by the Truck

Manufacturers Association (TMA) to amend Standard No. 121 included,

among other things, a request for an additional weight allowance for a

rollbar of up to 1,000 pounds for the straight line stopping distance

tests for tractors, trucks, and buses in the lightly-loaded condition.

The rollbar is intended to provide driver protection in the event of a

rollover that could occur while testing heavy vehicles in limit-

performance maneuvers. [The rollbar portion of the TMA petition was

granted. In a notice published in the Federal Register on February 3,

1999 we proposed allowing the use of a rollbar in compliance testing

(64 FR 5259).] We believe that in order to provide adequate protection

for test drivers, the same provision for a rollbar should be permitted

for the braking-in-a-curve test for single-unit vehicles. Therefore, we

propose that the braking-in-a-curve test in the lightly-loaded

condition include the unloaded vehicle weight plus up to 1,500 pounds

for driver, instrumentation, and a rollbar. The 1,500 lb figure is

based on the existing definition of ``lightly-loaded vehicle weight''

for vehicles with GVWRs of over 10,000 lbs. and the 1,000 lbs. for a

rollbar. That term is defined in S4 of Standard No. 105 as the unloaded

vehicle weight plus up to 500 lbs., including driver and

instrumentation. This weight provision need not be included for tests

in the fully-loaded condition since the weight of these items would be

included as part of the load.

J. Loaded Test Weight

NHTSA proposes to use the existing definitions of ``loaded test

weight'' in Standard Nos. 105 and 121 for the braking-in-a-curve tests

for single-unit trucks and buses.

The existing definitions, which are used for straight-line stopping

distance tests required for loaded single-unit trucks and buses,

specify that the vehicle be loaded to its GVWR in proportion to each

GAWR. An exception is provided in Standard No. 105 for cases in which

an axle weight in the unloaded condition already exceeds its

proportional GAWR with the vehicle loaded to GVWR. In such cases, the

vehicle is loaded only over the other axle(s) until the GVWR is

reached.

The loading requirements for tractors in Standard No. 121,

applicable to both straight line stopping distance and braking-in-a-

curve tests, provide that the center of gravity height of the ballast

shall be less than 24 inches above the fifth wheel of the tractor. This

is a relatively low center of gravity loading that is used to evaluate

the braking performance of loaded tractors during the braking-in-a-

curve test and minimizes the risk of vehicle rollover during the test.

This loading condition also provides a uniform test condition for

tractors so that results will be repeatable from one test to another.

The loading of straight trucks during the braking-in-a-curve tests

conducted at VRTC included a load frame and ballast with a combined

center of gravity height of 32 inches above the frame rail of the

chassis cab. This loading scheme was selected to adequately evaluate

the braking performance of the trucks while minimizing the risk of

rollover. The purpose of the braking-in-a-curve test is to evaluate the

vehicle's yaw stability and the driver's ability to maintain steering

control, not to evaluate the vehicle's roll stability. Therefore, a

reasonable loading scheme with respect to load center of gravity height

is needed to ensure the safety of the test procedure.

As in the case with the unloaded single-unit truck and bus vehicle

tests, we do not conduct compliance testing on incomplete vehicles in

the loaded condition. Since there are many configurations of bodies and

equipment used in the completion of single-unit trucks, including

flatbeds, tankers, van bodies, dump bodies, rollbacks, mixers, etc.,

and other configurations of vehicles not based on typical chassis-cabs,

such as step vans, motor homes, and certain fire trucks, we believe

that it would not be possible to specify a loading scheme that would be

applicable to all single-unit trucks and buses. We are aware of efforts

by the SAE Truck and Bus Vehicle Deceleration and Stability

Subcommittee to revise Recommended Practice (RP) J1626, Braking,

Stability, and Control Performance Test Procedures for Air-Brake

Equipped Trucks, to incorporate loading requirements which can be used

for testing incomplete chassis-cabs. However, we do not expect that

this RP will address testing of completed single-unit vehicles or

incomplete/completed vehicles manufactured on other types of chassis.

For many types of vehicles, we will need to develop suitable loading

schemes on a case-by-case basis, depending on the vehicle type. For

example, a passenger bus could be loaded using sand bags or other heavy

objects placed in all passenger seating positions and on the floor or

in cargo areas to achieve GVWR loading in proportion to the vehicle's

GAWRs.

[[Page 71383]]

K. Initial Brake Temperature

NHTSA proposes an initial brake temperature between 150 and 200

degrees F.

In the September 1993 NPRM, we proposed using a higher initial

brake temperature range of 250 to 300 degrees F. The intent was to

reduce the amount of time needed to conduct the road tests by reducing

the amount of time that brakes would need to cool between stops. In

general, comments on the proposed increased temperature range stated

that the increased temperatures would necessitate design changes in the

braking system by requiring more aggressive linings, and that this

increased initial temperature range would not be consistent with

testing that had been conducted in the past using the lower initial

temperature range. These negative aspects of the proposed temperature

range outweighed the small benefits in reduced testing time, so we

retained the 150 to 200 degree initial brake temperature criteria. For

those reasons, we believe that this initial temperature range is also

appropriate for testing of single-unit trucks and buses for the

braking-in-a-curve test.

L. Transmission Position

NHTSA proposes that the braking-in-a-curve test for single-unit

trucks and buses be conducted either with the vehicle's transmission

placed in a neutral position or with the clutch pedal depressed. This

technique minimizes the effects of engine and driveline retardation,

which is necessary in order to solely evaluate the performance of the

braking system without undue driveline influences. Although the effects

of engine and driveline retardation can affect the stability of medium

and heavy vehicles when operated on low coefficient of friction road

surfaces, this is not the primary purpose of the braking-in-a-curve

test. The proposed test condition also helps to ensure test

repeatability and reproducibility.

M. Test Sequence

NHTSA proposes that the braking-in-a-curve test for air-braked

single-unit trucks and buses be conducted immediately after the burnish

procedure as indicated in Table I of Standard No. 121, with the loaded

tests followed by the unloaded tests. We further propose that the

braking-in-a-curve test for hydraulic-braked single-unit trucks and

buses be conducted immediately after the post-burnish brake adjustment

in S7.4.2.2, with the loaded tests followed by the unloaded tests.

We originally selected this test sequence for air-braked tractors

so that vehicle stability during the braking-in-a-curve test could be

checked early in the test sequence. In the final rule of December 13,

1995, we amended the test sequence by placing both braking-in-a-curve

tests immediately after the burnish for several reasons: (a) to allow

test track wetting to be accomplished more efficiently; (b) to minimize

ABS performance variability that might occur after tires are subjected

to high-speed stopping distance tests on a high coefficient of friction

surface; and (c) to minimize vehicle transfers for those manufacturers

that use a different test site for ABS testing. The same sequence is

being proposed in this notice. In addition, the loaded test is proposed

to be conducted prior to the unloaded test, since the vehicle would

already be fully-loaded immediately following the brake burnish.

N. Special Drive Considerations

We propose that single-unit trucks and buses being tested in the

braking-in-a-curve test under Standard No. 105 be subjected to the same

road test provisions as are currently specified for trucks and buses in

subsection S6.1 of Standard No. 121.

Paragraph S6.1.11 specifies that vehicles with interlocking axles

or front wheel drive systems which are engaged and disengaged by the

driver be tested with such systems disengaged. As in the case of the

transmission, the driveline effects of a front wheel drive or interaxle

locking system on the performance of the vehicle in the braking-in-a-

curve test should be minimized to the extent possible. Since the road

test conditions in Standard No. 105 do not include this provision, we

propose the same provision under Standard No. 105 as under Standard No.

121. We invite comments on this issue.

IV. Intermediate and Final Stage Manufacturers

In the NPRM of September 28, 1993 and the stability and control

final rule of March 10, 1995, we discussed the issue of certification

to Standard Nos. 105 and 121 for vehicles manufactured in two or more

stages. One concern was that final stage manufacturers would not be

able to conduct the road testing for each type of vehicle they

manufacture. We stated that in many cases the incomplete vehicle

manufacturer could pass through certification to the final stage

manufacturer if the final stage manufacturer adhered to specifications

provided by the incomplete vehicle manufacturer, for example, by not

exceeding the GAWRs, not altering any brake component, and keeping the

center of gravity of the completed vehicle within a specified envelope.

In cases for which pass-through certification was not available,

such as vehicles built in one stage, the manufacturer could use

engineering analysis, actual testing, or computer simulations to

certify their vehicles. Moreover, a manufacturer need not conduct such

testing or analysis itself, but could base its certification on the

services of independent engineers and testing laboratories, or could

join together through trade associations to sponsor testing or

analysis. Finally, manufacturers could rely on testing and analysis by

third parties, such as brake manufacturers, who typically perform

extensive analyses and tests of their products. Based on these various

options available to vehicle manufacturers, we do not believe that the

proposed performance requirements pose any significant certification

burdens for final stage manufacturers or other small manufacturers.

Another concern was that the pass-through certification from an

incomplete vehicle manufacturer could have design limitations that are

so design restrictive that final stage manufacturers would not be able

to readily adhere to them. As stated above, however, the testing at

VRTC showed that varying the load height on the trucks being tested did

not have an appreciable effect on the results of the braking-in-a-curve

test. Therefore, based on the testing performed to date, we are not

aware of any significant additional requirements that would be

necessary as a result of implementing the braking-in-a-curve test for

single-unit trucks and buses that would result in the pass-through

certification becoming unduly restrictive for final stage

manufacturers.

V. Benefits

NHTSA published a detailed estimate of the costs and benefits of

equipping medium and heavy vehicles with ABS in the February 1995 Final

Economic Assessment (FEA) (see footnote 1 above). This FEA provided

estimates for the reduction in fatal, injury-producing, and property-

damage-only (PDO) crashes by equipping medium and heavy vehicles with

ABS and implementing/reimplementing straight line stopping distance

requirements. It also provided a detailed analysis of the projected

costs to consumers and vehicle manufacturers to meet the ABS

requirements. The projected annual benefits of ABS were summarized for

all medium and heavy vehicles as follows:

1. 29,103 crashes prevented per year.

2. 38,227 fewer vehicle involvements in PDO crashes.

[[Page 71384]]

3. 15,900 to 27,413 vehicle occupant injuries prevented per year.

4. 320 to 506 vehicle occupant fatalities prevented per year.

5. $457,780,795 to $552,769,946 of property damage prevented.

Table 6 on page V-12 of the FEA provides a breakdown of the

estimated benefits of ABS for each vehicle type including combination

vehicles, bobtail tractors, single-unit trucks, and buses. That table

also shows the reduced fatalities, injuries, and PDO crash damage to

other vehicles involved in crashes with these medium and heavy

vehicles. The breakdown did not differentiate between single-unit

trucks and buses equipped with air versus hydraulic braking systems. In

general, the table indicates that for single-unit trucks and buses

equipped with ABS, between 16 and 34 truck and bus occupant fatalities

will be prevented each year, and between 79 and 117 fatalities among

occupants of other vehicles will be prevented each year.

The potential benefits of applying the braking-in-a-curve

performance test to single-unit trucks and buses, compared with the

benefits of solely requiring the ABS equipment portions in the

respective safety standards, were not differentiated in the FEA nor for

the purposes of this rulemaking action. The full benefits projected in

the FEA are based on having both the equipment requirements and

performance tests to ensure that ABS installed on medium and heavy

vehicles performs with a maximum level of safety. The benefits

projected in the FEA reflect the installation of antilock brake systems

that were in use and on the road at the time of the analysis. We have

since conducted ABS braking-in-a-curve tests, on six single-unit

vehicles--four straight trucks and two buses--that are now required to

have ABS installed. All these vehicles passed the performance

requirements with a large margin of compliance. While we project no

additional benefits by requiring these performance tests, they will

help assure that minimum levels of safety are maintained.

VI. Costs

In the February 1995 FEA, NHTSA provided an extensive evaluation of

the estimated costs to vehicle manufacturers and consumers associated

with requiring ABS on medium and heavy vehicles. The majority of costs

to consumers were the increased purchase price of vehicles equipped

with ABS, in-service costs to perform maintenance and repairs to the

ABS, and lost revenue and increased fuel consumption due to the extra

weight of the ABS equipment. The FEA also included the costs to vehicle

manufacturers to comply with the ABS requirements and the stopping

distance requirements in the companion final rule. Although specific

costs were not identified for conducting the braking-in-a-curve test

for tractors, the costs to vehicle manufacturers (excluding the cost

for the ABS equipment which would be passed on to the consumer) for all

medium and heavy vehicles to comply with the new stopping distance

requirements were estimated as follows:

Air-braked vehicles--Total cost of $11.71 million, including

$6.0 million for compliance testing costs and $5.71 million related

to vehicle modifications necessary to improve vehicle stopping

distance performance. For the estimated 208,500 air-braked vehicles

produced each year, the total estimated cost per vehicle for the

first year after the final rules was $56. For the remaining years

after the first year, the estimated cost per vehicle was $37.

Hydraulic-braked vehicles--Total cost of $1.0 million, all for

compliance testing. During the first year after the final rules, an

estimated 194,400 vehicles would be affected for a cost per vehicle

estimated at $5. In the years following the first year, the cost per

vehicle was estimated at $2 per vehicle.

The first-year costs are higher because the additional road test

requirements imposed by the control and stability final rule and the

stopping distance final rule would require compliance testing of all

affected vehicles that are already in production, while in the later

years, only new vehicle designs or vehicles with modifications to their

braking systems would need to be tested. Complete compliance tests for

both hydraulic-and air-braked vehicles were estimated to cost $5,000

per vehicle per test.

NHTSA provides the following estimates for the cost of implementing

the braking-in-a-curve test for single-unit trucks and buses. A stand-

alone braking-in-a-curve test is estimated to cost $1500, and the

incremental cost to incorporate the braking-in-a-curve test into a

complete Standard No. 105 or 121 compliance test is estimated at

$1,000.

For air-braked single-unit vehicles: As shown in Table 13 of the

FEA, an estimated 53,900 single-unit trucks and 7,000 buses would be

affected annually. For all air-braked vehicles, including tractors, the

FEA estimated that twelve medium and heavy vehicle manufacturers would

need to conduct 100 compliance tests each, for a total of 1200

compliance tests. If only single-unit trucks and buses are to be

tested, there are fewer numbers of these vehicles produced compared to

tractors, but there are more vehicle types that would need to be

tested. We estimated, therefore, that the twelve manufacturers would

need to conduct 60 compliance tests each, for a total of 720 tests, in

the first year that the braking-in-a-curve test would become effective,

at a cost of $1,080,00 (720 x $1,500). This assumes that compliance

testing for the stopping distance requirements would have already been

conducted. The cost per air-braked vehicle is estimated to be about $18

($1,080,000 60,900). In the later years, it is estimated that

30 compliance tests would be required annually, for a total cost of

$360,000 (12 x 30 x $1,000). The cost per air-braked vehicle in the

later years would be about $6 ($360,000 60,900).

Hydraulic-braked single-unit vehicles: As shown in Table 13 of the

FEA, an estimated 194,400 single-unit vehicles would be affected

annually. Assuming that the timing of the braking-in-a-curve test is

such that all of the affected vehicles would have this test requirement

included in a complete compliance test to all of the requirements in

Standard No. 105, the $1,000 per test cost is used. The estimates in

the FEA were that 10 vehicle manufacturers would need to conduct 20

compliance tests each, for a total of 200 compliance tests, at an

annual cost of $200,000 (200 x $1,000). The cost per vehicle is then

estimated at about $1 ($200,000 194,400). This cost per

vehicle would be the same in the later years.

Implementing the braking-in-a-curve performance test for single-

unit vehicles with either hydraulic or air brakes is not expected to

result in any increases in vehicle equipment or manufacturing costs,

since these vehicles are already required to be equipped with ABS. As

long as the antilock braking systems that are being installed on

affected vehicles perform as they are supposed to, that is, preventing

wheel lockup under a variety of road and load conditions, then these

vehicles should be able to comply with the braking-in-a-curve test

without additional development or equipment costs to the vehicle

manufacturer. Thus all costs associated with requiring the braking-in-

a-curve test are limited to the cost of vehicle manufacturers

performing road tests and do not include equipment costs.

VII. Compliance Date

NHTSA proposes that the compliance date for the braking-in-a-curve

test requirements, for both air and hydraulic-braked single unit trucks

and buses, be two years after publication of the final rule in the

Federal Register. Due to the operating conditions of these trucks,

which often call for specialized designs, manufacturers produce a large

[[Page 71385]]

number of different truck configurations. The proposal would provide

sufficient leadtime to ensure that the manufacturers can test a

relatively large number of vehicle types and configurations. At the

same time, it would also ensure that this important check of vehicle

stability is implemented in a timely manner to ensure the safe

operation of these vehicles. Optional early compliance would be

permitted on and after the date of publication of the final rule in the

Federal Register.

VIII. Rulemaking Analyses and Notices

A. Executive Order 12866 and DOT Regulatory Policies and Procedures

This document has not been reviewed under Executive Order 12866,

Regulatory Planning and Review.

We have analyzed the impact of this rulemaking and have determined

that it is not ``significant'' within the meaning of DOT's regulatory

policies and procedures. This action proposes to amend the air and

hydraulic brake standards applicable to medium and heavy vehicles to

provide for a braking-in-a-curve test for single-unit trucks and buses

to enhance the stability and control of those vehicles. As discussed in

Section VII above, we estimate that the total cost of the braking-in-a-

curve test for manufacturers of single-unit vehicles equipped with air

brakes would be approximately $1,080,000 the first year, for a per-

vehicle cost about $18. In the later years, we estimate that the per-

vehicle cost would be approximately $6, for a total cost of about

$360,000. For hydraulic-braked single-unit vehicles, we estimate the

annual cost to manufacturers of the braking-in-a-curve test to be about

$200,000, for a per-vehicle cost of about $1. We estimate that this

cost would be the same in the later years.

As discussed above, NHTSA evaluated in detail the costs and

benefits of equipping medium and heavy vehicles with ABS. We believe

that the full array of costs and benefits discussed in the FEA will not

be fully attained until 10 years or more since it will take that long

until all existing non-ABS medium and heavy vehicles have been replaced

by newer vehicles equipped with ABS. Accordingly, we believe that the

projected figures in the FEA are still valid and on that basis, we have

concluded that preparation of another full regulatory evaluation is not

warranted.

B. Regulatory Flexibility Act

NHTSA has considered the effects of this rulemaking action under

the Regulatory Flexibility Act, 5 U.S.C. 601, et seq. I hereby certify

that this notice of proposed rulemaking would not have a significant

impact on a substantial number of small entities.

The following is our statement providing the factual basis for this

certification (5 U.S.C. 605(b)). The amendments proposed in this action

would primarily affect manufacturers of medium and heavy vehicles,

including single-unit trucks and buses. The Small Business

Administration (SBA) regulation at 13 CFR part 121 defines a small

business as a business entity that operates primarily within the United

States (13 CFR 121.105(a)).

SBA's size standards are organized according to Standard Industrial

Classification (SIC) codes. SIC code No. 3711, Motor Vehicles and

Passenger Car Bodies, prescribes a small business size standard of

1,000 or fewer employees. SIC code No. 3714, Motor Vehicle Parts and

Accessories, prescribes a small business size standard of 750 or fewer

employees.

The amendments proposed in this rulemaking add an additional test

procedure to the air and hydraulic brake standards, applicable only to

medium and heavy single-unit trucks and buses. These amendments do not

apply to trailers. The amendments, if adopted, would impose minimal

testing costs to manufacturers of the affected vehicles, most if not

all of which would not qualify as small businesses under SBA

guidelines. We estimate that the proposed amendments, if adopted, would

result in minimal, if any, additional costs to small businesses or

consumers. Accordingly, there would be no significant impact on small

businesses, small organizations, or small units by these amendments.

For those reasons, the agency has not prepared a preliminary regulatory

flexibility analysis.

C. Executive Order No. 12612, Federalism

NHTSA has analyzed this rulemaking action in accordance with the

principles of E.O. 12612 and has determined that this rule does not

have sufficient federalism implications to warrant preparation of a

Federalism Assessment.

D. National Environmental Policy Act

NHTSA has analyzed this rulemaking action for the purposes of the

National Environmental Policy Act and has determined that

implementation of this rulemaking action would not have any significant

impact on the quality of the human environment.

E. Paperwork Reduction Act

In accordance with the Paperwork Reduction Act of 1980, Pub L. 96-

511, NHTSA states that there are no information collection requirements

associated with this rulemaking action.

F. Unfunded Mandates Reform Act

The Unfunded Mandates Reform Act of 1995 (Pub L. 104-4) requires

agencies to prepare a written assessment of the costs, benefits, and

other effects of proposed or final rules that include a Federal mandate

likely to result in the expenditure by state, local, or tribal

governments, in the aggregate, or by the private sector, of more than

$100 million annually. This proposed rule does not meet the definition

of a Federal mandate because, if adopted, annual expenditures by the

stated entities will not exceed the $100 million threshold.

G. Civil Justice Reform

The amendments proposed in this rulemaking action would not have

any retroactive effect. Under 49 U.S.C. 30103(b), whenever a Federal

motor vehicle safety standard is in effect, a state or political

subdivision of a state may prescribe or continue in effect a standard

applicable to the same aspect of performance of a motor vehicle only if

that standard is identical to the Federal standard. However, the United

States government, a state or political subdivision of a state may

prescribe a standard for a motor vehicle or motor vehicle equipment

obtained for its own use that imposes a higher performance requirement

than that required by the Federal standard. Section 30161 of Title 49,

U.S. Code sets forth a procedure for judicial review of final rules

establishing, amending or revoking Federal motor vehicle safety

standards. A petition for reconsideration or other administrative

proceeding is not required before parties may file suit in court.

IX. Comments

How Do I Prepare and Submit Comments?

Your comments must be written and in English. To ensure that your

comments are correctly filed in the Docket, please include the docket

number of this document in your comments.

Your comments must not be more than 15 pages long. (49 CFR 553.21).

We established this limit to encourage you to write your primary

comments in a concise fashion. However, you may attach necessary

additional documents to your comments. There is no limit on the length

of the attachments.

[[Page 71386]]

Please submit two copies of your comments, including the

attachments, to Docket Management at the address given above under

ADDRESSES.

How Can I Be Sure That My Comments Were Received?

If you wish Docket Management to notify you upon its receipt of

your comments, enclose a self-addressed, stamped postcard in the

envelope containing your comments. Upon receiving your comments, Docket

Management will return the postcard by mail.

How Do I Submit Confidential Business Information?

If you wish to submit any information under a claim of

confidentiality, you should submit three copies of your complete

submission, including the information you claim to be confidential

business information, to the Chief Counsel, NHTSA, at the address given

above under FOR FURTHER INFORMATION CONTACT. In addition, you should

submit two copies, from which you have deleted the claimed confidential

business information, to Docket Management at the address given above

under ADDRESSES. When you send a comment containing information claimed

to be confidential business information, you should include a cover

letter setting forth the information specified in our confidential

business information regulation. (49 CFR part 512.)

Will the Agency Consider Late Comments?

We will consider all comments that Docket Management receives

before the close of business on the comment closing date indicated

above under DATES. To the extent possible, we will also consider

comments that Docket Management receives after that date. If Docket

Management receives a comment too late for us to consider it in

developing a final rule (assuming that one is issued), we will consider

that comment as an informal suggestion for future rulemaking action.

How Can I Read the Comments Submitted by Other People?

You may read the comments received by Docket Management at the

address given above under ADDRESSES. The hours of the Docket are

indicated above in the same location.

You may also see the comments on the Internet. To read the comments

on the Internet, take the following steps:

Go to the Docket Management System (DMS) Web page of the

Department of Transportation (http://dms.dot.gov/).

On that page, click on ``search.''

On the next page (http://dms.dot.gov/search/), type in the

four-digit docket number shown at the beginning of this document.

Example: If the docket number were ``NHTSA-1998-1234,'' you would type

``1234.'' After typing the docket number, click on ``search.''

On the next page, which contains docket summary

information for the docket you selected, click on the desired comments.

You may download the comments. However, since the comments

are imaged documents, instead of word processing documents, the

downloaded comments are not word searchable.

Please note that even after the comment closing date, we will

continue to file relevant information in the Docket as it becomes

available. Further, some people may submit late comments. Accordingly,

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

List of Subjects in 49 CFR Part 571

Imports, Incorporation by reference, Motor vehicle safety, Motor

vehicles, Rubber and rubber products, Tires.

In consideration of the foregoing, 49 CFR part 571 would be amended

as follows:

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

1. The authority citation for part 571 would continue to read as

follows:

Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166;

delegation of authority at 49 CFR 1.50.

2. Section 571.105 would be amended by adding definitions of ``Full

brake application'' and ``Maximum drive-through speed'' to S4; by

revising S5.1, S6.9.2 the introductory text of S7, S7.5, and Table I;

and by adding S5.1.7 and S6.14, to read as follows:

Sec. 571.105 Standard No. 1059, Hydraulic brake and electric systems.

* * * * *

S4 Definitions.

* * * * *

Full brake application means a brake application in which the force

on the brake pedal reaches 150 pounds within 0.2 seconds from the point

of application of force to the brake control.

* * * * *

Maximum drive-through speed means the highest possible constant

speed at which the vehicle can be driven through 200 feet of a 500-foot

radius curve arc without leaving the 12-foot lane.

* * * * *

S5.1 Service brake systems. Each vehicle must be equipped with a

service brake system acting on all wheels. Wear of the service brake

must be compensated for by means of a system of automatic adjustment.

Each passenger car and each multipurpose passenger vehicle, truck, and

bus with a GVWR of 10,000 pounds or less must be capable of meeting the

requirements of S5.1.1 through S5.1.6 under the conditions prescribed

in S6, when tested according to the procedures and in the sequence set

forth in S7. Each school bus with a GVWR greater than 10,000 pounds

must be capable of meeting the requirements of S5.1.1 through S5.1.5,

and S5.1.7 under the conditions specified in S6, when tested according

to the procedures and in the sequence set forth in S7. Each

multipurpose passenger vehicle, truck and bus (other than a school bus)

with a GVWR greater than 10,000 pounds must be capable of meeting the

requirements of S5.1.1, S5.1.2, S5.1.3, and S5.1.7 under the conditions

specified in S6, when tested according to the procedures and in the

sequence set forth in S7. Except as noted in S5.1.1.2 and S5.1.1.4, if

a vehicle is incapable of attaining a speed specified in S5.1.1,

S5.1.2, S5.1.3, or S5.1.6, its service brakes must be capable of

stopping the vehicle from the multiple of 5 mph that is 4 to 8 mph less

than the speed attainable in 2 miles, within distances that do not

exceed the corresponding distances specified in Table II. If a vehicle

is incapable of attaining a speed specified in S5.1.4 in the time or

distance interval set forth, it must be tested at the highest speed

attainable in the time or distance interval specified.

* * * * *

S5.1.7 Stability and control during braking. When stopped four

consecutive times under the conditions specified in S6, each vehicle

with a GVWR greater than 10,000 pounds and manufactured on or after

(COMPLIANCE DATE, if adopted) must stop from 30 mph or 75 percent of

the maximum drive-through speed, whichever is less, at least three

times within the 12-foot lane, without any part of the vehicle leaving

the roadway. Stop the vehicle with the vehicle:

(a) Loaded to its GVWR, and

(b) At its unloaded weight, plus up to 500 pounds (including driver

and instrumentation), or at the manufacturer's option, at its unloaded

weight plus up to 500 pounds (including driver and instrumentation)

[[Page 71387]]

and plus not more than an additional 1000 pounds for a roll bar

structure on the vehicle.

* * * * *

S6.9.2 (a) For vehicles with GVWRs greater than 10,000 pounds, road

tests are conducted on a 12-foot-wide, level roadway, having a peak

friction coefficient of 0.9 when measured using an American Society for

Testing and Materials (ASTM) E 1136 standard reference test tire, in

accordance with ASTM Method E 1337-90, at a speed of 40 mph, without

water delivery. Burnish stops are conducted on any surface. The parking

brake test surface is clean, dry, smooth, Portland cement concrete.

(b) For vehicles with GVWRs greater than 10,000 pounds, stability

and control during braking tests are conducted 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.

* * * * *

S6.14 Special drive conditions. A vehicle with a GVWR greater than

10,000 pounds equipped with an interlocking axle system or a front

wheel drive system that is engaged and disengaged by the driver is

tested with the system disengaged.

* * * * *

S7. Test procedure and sequence. Each vehicle must be capable of

meeting all the applicable requirements of S5 when tested according to

the procedures and in 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, S5.1.3, and S5.1.7 in section S5.1, the applicable test

procedures and sequence are S7.1, S7.2, S7.4, S7.5, S7.9, S7.10, S7.11

and S7.18. However, at the option of the manufacturer, the following

test procedure 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, S7.11, and S7.18. The choice of

this option must 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 is required to be in neutral for a

deceleration, a stop or snub must 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 (a) Stability and control during braking (vehicles with GVWRs

greater than 10,000 pounds). Make four stops in the loaded condition

specified in S5.1.7(a) and then four stops in the unloaded condition

specified in S5.1.7(b). Use a full brake application for the duration

of the stop, with the clutch pedal depressed or the transmission

selector control in the neutral position, for the duration of each

stop.

(b) Service brake system--second effectiveness test. Repeat S7.3.

Then (for passenger cars and other vehicles with GVWRs of 10,000 pounds

or less) make four stops from 80 mph if the speed attainable in 2 miles

is not less than 84 mph.

* * * * *

Table I--Brake Test Procedure Sequence and Requirements

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

Test load

Sequence ---------------------------------- Test procedure Requirements

Light GVWR

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

1. Instrumentation check........ ............... ............... S7.2

2. First (preburnish) ............... X S7.3 S5.1.1.1

effectiveness test.

3. Burnish procedure............ ............... X S7.4 .....................

4. Braking-in-a-curve test...... X X S7.5(a) S5.1.7

5. Second effectiveness test.... ............... X S7.5(b) S5.1.1.2

6. First reburnish.............. ............... X S7.6 .....................

7. Parking brake................ X X S7.7 S5.2

8. Third effectiveness (lightly X ............... S7.8 S5.1.1.3

loaded vehicle).

9. Partial failure.............. X X S7.9 S5.1.2

10. Inoperative brake power and ............... X S7.10 S5.1.3

power assist units.

11. First fade and recovery..... ............... X S7.11 S5.1.4

12. Second reburnish............ ............... X S7.12 .....................

13. Second fade and recovery.... ............... X S7.13 S5.1.4

14. Third reburnish............. ............... X S7.14 .....................

15. Fourth effectiveness........ ............... X S7.15 S5.1.1.4

16. Water recovery.............. ............... X S7.16 S5.1.5

17. Spike stops................. ............... X S7.17 S5.1.6

18. Final inspection............ ............... ............... S7.18 S5.6

19. Moving barrier test......... ............... X S7.19 S5.2.2.3

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

* * * * *

3. Section 571.121 would be amended by revising S5.3, S5.3.6,

S5.3.6.2 introductory text and paragraph (a), S6.1.15, and Table I to

read as follows:

Sec. 571.121 Standard No. 121; Air brake systems.

* * * * *

S5.3 Service brakes--road tests. The service brake system on each

truck tractor must, under the conditions of S6, meet the requirements

of S5.3.1, S5.3.3, S5.3.4, and S5.3.6, when tested without adjustments

other than those specified in this standard. The service brake system

on each bus and truck other than a truck tractor must, under the

conditions of S6, meet the requirements

[[Page 71388]]

of S5.3.1, S5.3.3, and S5.3.4 when tested without adjustments other

than those specified in this standard. The service brake system on each

bus and truck other than a truck tractor manufactured on or after

[Compliance date to be inserted] must, under the conditions of S6, meet

the requirements of S5.3.1, S5.3.3, S5.3.4, and S5.3.6, when tested

without adjustments other than those specified in this standard. The

service brake system on each trailer must, under the conditions of S6,

meet the requirements of S5.3.3, S5.3.4, and S5.3.5 when tested without

adjustments other than those specified in this standard. However, a

heavy hauler trailer and the truck and trailer portions of an auto

transporter need not meet the requirements of S5.3.

* * * * *

S5.3.6 Stability and control during braking--trucks and buses. When

stopped four consecutive times for each combination of weight, speed,

and road conditions specified in S5.3.6.1 and S5.3.6.2, each truck

tractor must stop at least three times within the 12-foot lane, without

any part of the vehicle leaving the roadway. When stopped four

consecutive times for each combination of weight, speed, and road

conditions specified in S5.3.6.1 and S5.3.6.2, each bus and truck other

than a truck tractor manufactured on or after [Compliance date to be

inserted], must stop at least three times within the 12-foot lane,

without any part of the vehicle leaving the roadway.

* * * * *

S5.3.6.2 Stop the vehicle, with the vehicle:

(a) Loaded to its GVWR so that the load on each axle measured at

the tire-ground interface is most nearly proportional to the axles'

respective GAWRs, without exceeding the GAWR of any axle, and

(b) * * *

* * * * *

S6.1.15 Initial brake temperature. Unless otherwise specified, the

initial brake temperature is not less than 150 deg.F and not more than

200 deg.F. The temperature of each brake is measured by a single plug-

type thermocouple installed in the center of the lining surface of the

most heavily loaded shoe or pad as shown in Figure 2. The thermocouple

is outside any center groove.

* * * * *

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 single-unit

vehicle or for a truck tractor with a loaded unbraked control trailer;

(b) With the vehicle at unloaded weight plus up to 1,500 lbs, stop

the vehicle from 30 mph using the service brake, for a truck tractor or

a single-unit vehicle;

3. Manual adjustment of the service brakes allowed for truck

tractors and single-unit vehicles 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 1500

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.

* * * * *

Issued on December 14, 1999.

Stephen R. Kratzke,

Acting Associate Administrator for Safety Performance Standards.

[FR Doc. 99-32889 Filed 12-20-99; 8:45 am]

BILLING CODE 4910-59-P