Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations 13285

[FR Doc. 95–5410 Filed 3–7–95; 8:45 am]

BILLING CODE 4910–59–C
13286 Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations

1Hereafter, referred to as heavy vehicles.

2Today’s companion final rule to require heavy

vehicles to be equipped with antilock brake systems

(ABS) will prevent braking-induced loss-of-control

crashes.

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety

Administration

49 CFR Part 57l

[Docket No. 93–06; Notice 3]

RIN 2127–AD07

Federal Motor Vehicle Safety

Standards; Stopping Distance

Requirements for Vehicles Equipped

With Air Brake Systems

AGENCY: National Highway Traffic

Safety Administration (NHTSA),

Department of Transportation.

ACTION: Final rule.

SUMMARY: This notice reinstates

stopping distance performance

requirements in Standard No. 121, Air

Brake Systems, for medium and heavy

vehicles that are equipped with air

brake systems. The requirements specify

distances in which different types of

medium and heavy vehicle

configurations must come to a complete

stop from 60 mph on a high coefficient

of friction surface. The requirements are

designed to reduce the number and

severity of crashes.

This notice is one part of the agency’s

comprehensive effort to improve the

braking ability of heavy vehicles. In

another final rule published elsewhere

in today’s Federal Register, the agency

is adopting identical stopping distance

requirements for medium and heavy

vehicles that are equipped with

hydraulic brake systems. In a third final

rule that responds to the Intermodal

Surface Transportation Efficiency Act

(ISTEA) of 1991, the agency is requiring

medium and heavy vehicles to be

equipped with an antilock brake system

(ABS) to improve the lateral stability

and control of these vehicles during

braking.

DATES: Effective Dates: The amendments

become effective on March 1, 1997.

Compliance to § 571.121 with respect to

trailers and single unit trucks and buses

will be required as of March 1, 1998.

Petitions for Reconsideration: Any

petitions for reconsideration of this rule

must be received by NHTSA no later

than April 10, 1995.

ADDRESSES: Petitions for reconsideration

of this rule should refer to Docket 93–

06; Notice 3 and should be submitted to:

Administrator, National Highway

Traffic Safety Administration, 400

Seventh Street SW., Washington, DC

20590.

FOR FURTHER INFORMATION CONTACT: Mr.

George Soodoo, Office of Vehicle Safety

Standards, National Highway Traffic

Safety Administration, 400 Seventh

Street SW., Washington, DC 20590

(202–366–5892).

SUPPLEMENTARY INFORMATION:

I. Background

A. Brake Related Crashes

B. Braking Devices

II. NHTSA Activities

A. Regulatory History

B. Agency Research

C. Heavy Vehicle Safety Report to Congress

III. Agency Proposal

IV. Comments on the Proposal

V. Agency Decision

A. Overview

B. Stopping Distance Performance

1. Stopping Distance Requirements

2. Stopping Distance Test Conditions

a. Test Surface Specification

b. Wheel Lockup Restrictions

c. Control Trailer

d. Vehicle Loading

e. Initial Brake Temperature

f. Emergency Stopping Distance

Requirements

g. Burnish Procedure

h. Parking Brake Test

C. Threshold Pressure Requirement

D. Requirements for Brake Linings

E. Implementation Schedule

F. Intermediate and Final Stage

Manufacturers/Trailer Manufacturers

G. Costs

VI. Rulemaking Analyses and Notices

A. Executive Order 12866 and DOT

Regulatory Policies and Procedures

B. Regulatory Flexibility Act

C. Paperwork Reduction Act

D. National Environmental Policy Act

E. Executive Order 12612 (Federalism)

F. Civil Justice Reform

I. Background

A. Brake Related Crashes

Medium and heavy vehicles 1 are

involved in thousands of motor vehicle

crashes each year. One of the most

important factors that contributes to

these crashes is brake system

performance. Crashes in which braking

is a contributory factor can be further

subdivided into (1) crashes due to brake

failures or defective brakes, (2)

runaways on downgrades, due to

maladjusted or overheated brakes, (3)

crashes in which vehicles are unable to

stop in time, and (4) skidding,

jackknifing, or loss-of-control crashes

due primarily to locked wheels during

braking.

This final rule, reinstating stopping

distance requirements for air-braked

vehicles and the companion final rule

specifying stopping distance

requirements for hydraulically braked

heavy vehicles will reduce the severity

of or prevent crashes attributable to a

heavy vehicle’s inability to stop in

time.2 In these crashes, the heavy

vehicle’s brakes function, but do not

stop the vehicle quickly enough to avoid

a crash. One way to reduce the severity

or number of such crashes is to improve

heavy vehicle braking performance by

reducing the distance needed to stop a

vehicle. Even if crashes of this type

were not totally prevented by such

improvements in performance, the

improvements would reduce collision

impact speeds, and thus reduce crash

severity.

The following estimates regarding

heavy vehicle crashes are from

NHTSA’s 1992 General Estimates

System (GES) which is based on data

transcribed from a nationally

representative sample of state police

accident reports (PARs) and the Fatal

Accident Reporting System (FARS).

NHTSA estimates that in 1992 there

were about 168,000 crashes involving

heavy combination vehicles (excluding

truck tractors when operating bobtail,

i.e., without a trailer). These crashes

resulted in about 13,600 injuries and

387 fatalities to truck occupants and

about 51,500 injuries and 2,452 fatalities

to occupants of other involved vehicles.

For bobtail truck tractors alone, the

agency estimates that there were about

8,400 crashes resulting in about 1,200

injuries and 39 fatalities to truck

occupants and about 2,600 injuries and

178 fatalities to occupants of other

involved vehicles. For heavy single-unit

trucks, the agency estimates that there

were about 192,600 crashes resulting in

about 15,700 injuries and 165 fatalities

to truck occupants and about 48,300

injuries and 891 fatalities to occupants

of other involved vehicles. In addition,

crashes involving heavy vehicles result

in more expensive and severe property

damage than crashes involving light

vehicles.

It is very difficult to quantify the

number of crashes in which a vehicle’s

brakes are unable to stop the vehicle in

time. NHTSA estimates that in 1992

there were about 18,000 crashes

involving heavy combination vehicles

(excluding bobtail truck tractors). These

crashes resulted in about 1,800 injuries

and 57 fatalities to truck occupants and

about 8,400 injuries and 754 fatalities to

occupants of other involved vehicles.

For bobtail truck tractors alone, the

agency estimates that there were about

260 crashes resulting in about 100

injuries and 7 fatalities to truck

occupants and about 240 injuries and 48

fatalities to occupants of other involved
Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations 13287

3 ‘‘NHTSA Heavy Duty Vehicle Brake Research

Program Report No. 1, ‘‘Stopping Capability of Air

Braked Vehicles,’’ (DOT HS 806 738, April 1985)

and Report No. 9, ‘‘Stopping Distances of 1988

Heavy Vehicles.’’

4NHTSA Heavy Duty Vehicle Brake Research

Program Report No. 1, ‘‘Stopping Capability of Air

Braked Vehicles,’’ (DOT HS 806 738, April 1985)

and Report No. 9, ‘‘Stopping Distances of 1988

Heavy Vehicles.’’ DOT HS 807 531, February 1990.

vehicles. For heavy single-unit trucks,

the agency estimates that there were

about 30,100 crashes resulting in about

4,200 injuries and 17 fatalities to truck

occupants and about 15,000 injuries and

276 fatalities to occupants of other

involved vehicles. The Final Economic

Analysis (FEA) provides greater detail

about how today’s final rules will

reduce injuries and fatalities resulting

from such crashes.

The agency emphasizes that not all

inability-to-stop-in-time crashes are

preventable. Nevertheless,

improvements to heavy vehicle brake

systems should prevent or reduce the

severity of a significant number of these

crashes.

B. Braking Devices

In order to understand the discussion

of braking in this preamble, it is

necessary to be familiar with several

devices used in braking systems.

Therefore, the agency provides a brief

explanation of those devices below.

Automatic front axle limiting valves

(ALVs) automatically limit the amount

of braking pressure applied at steering

axle brakes. ALVs are typically installed

to allay the concern of some drivers

about loss of steering control due to

front wheel lockup during hard braking

and to reduce steering pull due to

unequal brake adjustment on the front

wheel brakes. However, these devices

can actually increase the likelihood of

drive axle and trailer lockup because the

brakes on the front axle do less than

their proportional share of the braking.

Therefore, drivers must apply brakes

harder to stop the vehicle. Accordingly,

stopping distance performance could, in

most cases, be improved by eliminating

the use of ALVs.

Bobtail proportioning valves (BPVs)

automatically reduce brake application

pressure to the drive axles of a bobtail

truck tractor, thereby allowing greater

use of the vehicle’s steering-axle braking

power. Bobtail tractors demonstrate the

worst stopping capability of all vehicle

types, primarily because the braking

systems of tractors are designed to

optimize their stopping distance when

they are towing a loaded trailer. Without

the trailer, the lack of load on the tractor

drive axles can cause premature wheel

lockup and reduced stopping capability.

An agency study found that, on average,

the stopping distance of bobtail tractors

is approximately 122 feet longer than

that of tractors when connected to

loaded trailers.3 However, significantly

shorter stops have been obtained when

bobtails are equipped with BPVs.

Load-Sensing Proportioning Valves

(LSVs) reduce the likelihood of

premature wheel lockup by

mechanically sensing drive-axle

suspension deflection that results from

weight transfer during braking, and

adjusting brake proportioning based on

different loading conditions. However,

LSVs cannot prevent lockup of a

vehicle’s brakes if they are applied too

hard, particularly on a low coefficient of

friction surface.

Antilock brake systems (ABSs)

automatically control the amount of

braking pressure applied to a wheel so

as to prevent wheel lock, thus

increasing stability and control in

emergency stops by preventing

skidding, spinning, and jackknifing.

Today’s stability and control final rule

provides a detailed discussion of these

devices.

II. NHTSA Activities

A. Regulatory History

In the notice of proposed rulemaking

(NPRM) to reinstate stopping distance

requirements for air-braked vehicles,

NHTSA provided a detailed discussion

of the regulatory and judicial history of

the stopping distance requirements for

air braked vehicles. (58 FR 11009,

February 23, 1993). When last in effect,

the stopping distance requirements in

Standard No. 121 required all heavy

vehicles to stop within 293 feet from a

speed of 60 mph on a high coefficient

of friction surface (i.e., a nonslippery

surface typical of dry concrete). (41 FR

8783, March 1, 1976).

In response to a suit challenging

Standard No. 121’s stopping distance

requirements, the United States Court of

Appeals for the 9th Circuit invalidated

the Standard’s stopping distance and

‘‘no lockup’’ requirements for trucks,

buses, and trailers in PACCAR v.

NHTSA, 573 F.2d 632, (9th Cir. 1978)

cert. denied, 439 U.S. 862 (1978). The

court held that NHTSA was justified in

promulgating a standard requiring

improved air brake systems and stability

mechanisms. However, after reviewing

the record about reliability problems

with antilock brake systems then in use,

the court held that the standard was

‘‘neither reasonable nor practicable at

the time it was put into effect.’’

The court further stated that:

* * * those parts of the Standard requiring

heavier axles and the antilock device should

be suspended. The evidence indicates that

this can be accomplished if we hold, as we

do, that the stopping distance requirements

from 60 mph are invalid * * * We hold only

that more probative and convincing data

evidencing the reliability and safety of

vehicles that are equipped with antilock and

in use must be available before the agency

can enforce a standard requiring its

installation.

The stability and control final rule

contains a detailed discussion about the

PACCAR decision and how the agency

has responded to the findings in that

decision. The Agency has decided to

specify different stopping distances for

different configurations of heavy

vehicles. Today’s requirements can

further be distinguished from those

invalidated in the 1970s by the fact that

manufacturers will not need to

significantly redesign their brakes or use

overly aggressive foundation brakes to

comply with the requirements being

established in today’s final rule.

Even though the stopping distance

requirements being specified in today’s

final rule are generally less stringent for

some configurations than those

invalidated by the PACCAR decision,

the agency believes that the braking

requirements in today’s final rules,

taken as a whole, significantly enhance

the overall braking performance of airbraked vehicles given the agency’s

decision to require these vehicles to be

equipped with ABS.

B. Agency Research

As a part of its review of heavy

vehicle braking, NHTSA has issued two

reports on the stopping distance

capability of several different types of

heavy air-braked vehicles in various

loading conditions.4 The agency also

tested some vehicles equipped with

ALVs, BPVs, and ABS, thus allowing

comparisons of stopping distances with

and without these devices. The tests

were conducted on school buses, transit

buses, single unit trucks, tractor trailers

in the loaded and empty conditions and

with various equipment (with ABS

activated and deactivated, and with and

without ALVs and BPVs). Among the

conclusions reached by the agency on

the basis of the test data were: (1) ALVs

significantly degrade straight line

stopping performance, especially in the

bobtail configuration (with stopping

distances as long as 531 feet); (2) BPVs

significantly reduce the stopping

distances of bobtail tractors; (3) ABSs

are effective in providing short, stable

stops in all operating conditions; (4)

ABSs provide the greatest performance

gain in the bobtail configuration, where

stable stops as short as 233 feet were

obtained; (5) braking performance of

bobtail tractors and empty single unit
13288 Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations

5This report may be examined at the Agency’s

Technical Reference Office, room 5108, at no

charge. It is available from the National Technical

Information Service (NTIS), Springfield, VA 22161

for a small charge.

6As explained below, the final rule refers to this

concept as ‘‘momentary wheel lockup.’’

trucks could be improved by removing

ALVs from both vehicle types and

installing BPVs on bobtails; and (6) a

stopping distance performance

requirement for truck tractors with

empty trailers would not provide any

additional performance benefits that

could not be achieved through

specifying requirements for either the

bobtail or loaded condition.

C. Heavy Vehicle Safety Report to

Congress

In response to section 9107 of the

Truck and Bus Regulatory Reform Act of

1988, NHTSA submitted a report to

Congress titled ‘‘Improved Brake

Systems for Commercial Vehicles.’’

(DOT HS 807 706, April 1991.) 5 After

discussing crash data concerning heavy

vehicle brake systems, the report

explained the factors that are related to

braking effectiveness, stability and

control during braking, and braking

system compatibility. The report

indicated that stopping distances and

vehicle stability could be improved by

not equipping heavy vehicles with

ALVs and instead equipping them with

BPVs, load-sensing proportioning

valves, and antilock brake systems.

III. Agency Proposal

On February 23, 1993, NHTSA

proposed to amend Standard No. 121 to

reinstate stopping distance performance

requirements for stops from 60 mph on

a high coefficient of friction surface for

trucks, truck tractors, and buses that are

equipped with air brake systems (58 FR

11009). Based on testing at VRTC, the

Agency proposed different stopping

distances for different configurations of

heavy vehicles. Specifically, the Agency

proposed that unloaded single unit

trucks and bobtail tractors stop within

335 feet, loaded single unit trucks stop

within 310 feet, and all buses stop

within 280 feet. The Agency proposed

two alternatives for testing a truck

tractor in the loaded condition and

stated that one of the alternatives would

be chosen for the final rule. The first

alternative proposed that the truck

tractor be tested with a braked control

trailer and stop within 280 feet, while

the second alternative proposed that the

truck tractor be tested with an unbraked

control trailer and stop within 355 feet.

The Agency explained that its long-term

objective is to upgrade the braking

efficiency of heavy vehicles to enable

them to make controlled, stable stops,

under all loading and road surface

conditions. The Agency believed that

the proposed requirements would

reduce the disparity in braking ability

between heavy vehicles and passenger

cars. On the same day, the Agency

proposed identical stopping distance

requirements for heavy vehicles

equipped with hydraulic brakes (58 FR

11003). The Agency stated that many

vehicles were already able to comply

with the proposed requirements. The

inadequate performance of those

vehicles that were not able to comply

was due to either poor brake torque

balance between the vehicles’ axles

resulting in premature lockup of the

wheels on the vehicles’ rear axles or a

lack of sufficient total brake torque

capability. Those vehicles that exhibited

poor brake balance could be brought

into compliance by installing ABS, or by

adding BPVs and/or eliminating ALVs.

Those vehicles that lack sufficient total

brake torque capability could be brought

into compliance by incorporating

relatively minor changes to their

foundation brake components involving

the substitution of other currently

available components.

NHTSA proposed that air-braked

vehicles would have to come to a

complete stop within a 12-foot-wide

lane with restrictions on which wheels

would be permitted to lockup during

the stop. The proposal requested

comments about whether and to what

degree wheel lockup during testing

would be permitted. Specifically, the

Agency proposed to allow unlimited

lockup below 20 mph and defined two

types of wheel lockup allowed above 20

mph: ‘‘permissible wheel lockup,’’

which is defined as 100 percent wheel

slip of one or more wheels for a

duration of one second or less 6 for

testing purposes, and ‘‘limited lockup,’’

which is defined as lockup of not more

than one wheel per axle or two wheels

per tandem. In addition, NHTSA

proposed test conditions related to the

road test surface, the use of a braked or

unbraked control trailer, and the initial

brake temperature. NHTSA also

proposed specifying a threshold

pressure to enhance brake force

compatibility between tractors and

trailers.

IV. Comments on the Proposal

NHTSA received 49 comments in

response to the NPRM. Commenters

included heavy vehicle manufacturers,

brake manufacturers, safety advocacy

groups, heavy vehicle users, industry

trade associations, and other

individuals. The American Automobile

Manufacturers Association (AAMA)

submitted joint comments on behalf of

the eight major domestic manufacturers

of heavy vehicles: Chrysler, Ford,

Freightliner, General Motors (GM),

Mack Trucks, Navistar, PACCAR, and

Volvo-GM.

All the commenters supported the

Agency’s decision to reinstate stopping

distance requirements for heavy

vehicles equipped with air brakes.

However, they offered mixed views

about the specific stopping distances

being proposed. GM, Navistar, Heavy

Duty Brake Manufacturers Council

(HDBMC), and Rockwell WABCO stated

that the proposed stopping distance

requirements are appropriate. In

contrast, the Insurance Institute for

Highway Safety (IIHS), the Coalition for

Consumer Health, and Advocates for

Highway Safety (Advocates) believed

that the required distances should be

much shorter for trucks and buses.

Advocates stated that the proposal did

little more than ‘‘grandfather’’ existing

braking capabilities and therefore would

not result in the best available braking

performance for large trucks.

The American Trucking Association

(ATA), IIHS and several other

commenters suggested that the Agency

should merge the proposed stopping

distance and stability requirements into

a common rulemaking, thereby allowing

the industry to implement a more

effective test program.

Commenters also addressed specific

issues raised in the NPRM, including

vehicle test speed, the test surface

specification, the control trailer, wheel

lockup restrictions, the initial brake

temperature, the failed system test,

vehicle loading, the threshold pressure

requirements, the parking brake test, the

burnish procedures, and the

implementation schedule for the

requirements. More specific discussions

of these comments, and the Agency’s

responses to them, are set forth below.

V. Agency Decision

A. Overview

Based on the Fatal Accident Reporting

System (FARS) and other crash data,

test data from the agency’s heavy

vehicle brake research program,

comments on the NPRM, and other

available information, NHTSA has

decided to amend Standard No. 121 to

reinstate stopping distance performance

requirements for heavy vehicles that are

equipped with air brake systems.

Separate requirements for stopping from

60 mph on a high coefficient of friction

surface are specified for four different

heavy vehicle configurations. The

requirements are designed to reduce the
Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations 13289

7The final rule amending Standard No. 105

discusses in detail the stopping distances

applicable to hydraulic-braked school buses.

8As explained in the section below titled ‘‘control

trailers,’’ the agency proposed but decided not to

adopt a revised braked control trailer test condition.

distance needed for these vehicles to

come to a complete stop, thereby

reducing the severity and number of

crashes.

As noted above, this notice is one part

of the Agency’s comprehensive effort to

improve the braking ability of heavy

vehicles. In a second final rule

published elsewhere in today’s Federal

Register, the Agency is adopting

identical stopping distance

requirements for heavy vehicles that are

equipped with hydraulic brake systems.

The Agency believes that it is

appropriate to specify identical stopping

distance requirements for similar

vehicles. In a third final rule, the

Agency is responding to the Intermodal

Surface Transportation Efficiency Act

(ISTEA) of 1991 by requiring each heavy

vehicle to be equipped with an antilock

brake system to improve its lateral

stability and control during braking.

B. Stopping Distance Performance

1. Stopping Distance Requirements

Based on its testing at VRTC, NHTSA

proposed different stopping distances

for various categories of vehicles when

tested at a speed of 60 mph on a surface

with a peak friction coefficient (PFC) of

0.9, as follows:

Loaded and Unloaded Buses..................280 ft.

Loaded Truck Tractors with Braked

Control Trailer..................................280 ft.

Loaded Truck Tractors with Unbraked

Control Trailer..................................355 ft.

Loaded Single-Unit Trucks ....................310 ft.

Unloaded Single-Unit Trucks & Truck

Tractors (Bobtail)..............................335 ft.

The agency proposed different

requirements, instead of a single acrossthe-board requirement like the one

invalidated by the PACCAR court,

because a single requirement for all

heavy vehicles with fully operational

service brakes would be too stringent for

bobtail tractors and unloaded single unit

trucks, but not stringent enough for

buses and for tractor trailers in the

loaded condition.

AAMA and most other industry

commenters agreed with the stopping

distance values proposed for the various

vehicle configurations. AlliedSignal

commented that these requirements are

compatible with its view of using BPVs

to achieve increased deceleration on airbraked tractors, while maintaining

lateral stability in the bobtail mode.

Nevertheless, it requested that ALVs not

be prohibited since it believed that these

devices are appropriate on some

vehicles, particularly those with large

front brakes. AlliedSignal recommended

that if an ALV is used on a vehicle, it

should be automatically deactivated

when the tractor is in the bobtail mode.

ATA agreed with the proposal to specify

different stopping distances for different

types and loadings of vehicles. It also

agreed with specifying the same

stopping distances for air-braked and

hydraulically-braked vehicles of the

same type and with the same loading.

Other commenters opposed some of

the proposed stopping distance values

on the ground that they were too

stringent. HDBMC stated that certain

vehicles would have difficulty

complying with the proposed stopping

distances because they are over-braked

when the rear axles are unloaded, and

under-braked during emergency system

stops. Lucas was concerned that the

service brake stopping distances

obtained during the agency’s testing do

not have a 10 percent margin less than

the proposed 280 feet from 60 mph. In

order to obtain an acceptable margin,

Lucas stated that vehicle manufacturers

will have to equip certain vehicles with

larger front brakes, which would

represent a major change on some

vehicles.

In contrast, other commenters stated

that the proposed stopping distances

were not sufficiently stringent.

Advocates stated that the proposed

stopping distances simply ratify the

braking distances currently achieved by

manufacturers and do not seek to

improve real-world braking

performance. It stated that except for the

280-foot requirement for buses and

loaded tractors with a braked control

trailer, all of the other proposed

stopping distances are longer than the

293 feet established before PACCAR.

Similarly, IIHS stated that the proposals

do not go far enough toward requiring

the best available braking for heavy

vehicles.

Based on the comments and other

available information, NHTSA has

decided to adopt the stopping distances

proposed in the NPRM for the following

categories of vehicles when tested at a

speed of 60 mph on a surface with a

PFC of 0.9:

Loaded and Unloaded Buses 7................280 ft.

Loaded Truck Tractors with Unbraked

Control Trailer 8................................355 ft.

Loaded Single-Unit Trucks ....................310 ft.

Unloaded Single-Unit Trucks & Truck

Tractors (Bobtail)..............................335 ft.

As it stated in the NPRM, NHTSA

agrees with HDBMC that a small

number of vehicles will have to be

modified to comply with the reinstated

stopping distance requirements. The

agency notes that the companion final

rule requiring heavy vehicles to be

equipped with antilock brake systems

will improve the braking of those

vehicles whose braking performance is

limited due to poor brake torque

balance, and will enable them to comply

with the stopping distance

requirements. For those vehicles that

will require changes to their foundation

brakes, so as to provide greater brake

torque capability, the agency believes

that adequate leadtime is being

provided to minimize the task of

achieving compliance with the

requirement.

NHTSA notes that while the

companion final rule requiring heavy

vehicles to be equipped with ABSs will

reduce the need to eliminate front axle

ALVs on single unit trucks and truck

tractors and to install rear axle BPVs on

truck tractors, the agency would still

encourage vehicle manufacturers to do

so. Vehicles without ALVs and/or with

BPVs can be braked at higher levels of

deceleration before the vehicle’s ABS is

activated, which the agency believes

will improve the vehicle’s driveability.

The Agency is aware of at least one

manufacturer of ABSs that currently

recommends the incorporation of BPVs

on truck tractors equipped with ABS.

2. Stopping Distance Test Conditions

a. Test Surface Specification

In the NPRM, NHTSA proposed that

the 60-mph stopping distance tests be

performed on a test surface with a PFC

of 0.9, which is typical of dry concrete.

In formulating the proposal, the agency

considered whether the proposed test

surface specification raises

practicability or objectivity concerns in

light of PACCAR. Based on its testing,

the agency tentatively concluded that

specifying a test surface with a high PFC

would reasonably represent stopping on

a dry surface and would not be a

significant source of variability in the

stopping distance tests. The Agency

requested comments on the proposed

test surface specification.

Several commenters addressed the

appropriate PFC for the test. AAMA and

Navistar commented that the test

surface should be specified at a PFC of

1.0 because that PFC value would

remove the influence of test road

variability from compliance testing.

AAMA provided data that showed that

in the course of six months, the PFC

varied between 0.85 and 0.95, and

averaged 0.90 over ten readings taken

approximately twice each month.

According to Navistar, its data showed

PFCs that ranged from 0.91 to 0.98.
13290 Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations

9Eleventh Informal Meeting on Harmonization of

Brake Standards, August 26–27, 1991 and 29th

Meeting of Experts on Brakes and Running Gear,

August 28–30, 1991.

AAMA argued that since the majority of

actual test surfaces nominally exceed

PFC 0.9, a specification of 0.9 would

impose a cost burden on manufacturers

trying to maintain the test surface near,

but below, the 0.9 value. AAMA stated

that ‘‘worldwide support’’ has been

expressed for specifying a test surface

with a PFC of 1.0. Volvo GM provided

results of the Motor Vehicle Safety

Research Advisory Committee

(MVSRAC) Antilock Brake System

(ABS) Task Force ‘‘Round Robin’’

testing, which showed that on high

coefficient of friction surfaces with PFCs

ranging from 0.87 to 1.00, the stopping

distances of the three test vehicles

remained relatively constant when

tested in the bobtail condition. This

indicates stopping performance on a dry

surface is not significantly affected by

variability. Strait-Stop requested that a

tolerance of ± 0.1 relative to 0.9 should

be specified to accommodate real-world

limitations.

Based on the industry-government

cooperative testing to evaluate the effect

of fluctuations of PFC on vehicle

stopping performance, NHTSA reaffirms

its belief that a PFC of 0.9 reasonably

represents a typical dry surface and will

not be a significant source of variability

in the stopping distance tests. (Public

Files Docket PF88–01, MVSRAC ABS

Task Force, Round Robin No. 1). 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. Variation of the

average stopping distances for the six

different surfaces (with PFCs ranging

from 0.89 to 0.94) was small, with the

deviation from the average being only 5

feet. Accordingly, the agency believes

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

rather than test surface variability.

NHTSA has decided that a test road

surface specification of PFC 1.0 would

result in practicability problems for the

agency, since it would have to conduct

compliance testing on a surface with a

PFC higher than 1.0. Such a surface is

difficult to find. The agency also notes

that General Motors conducted an

extensive survey of actual road surfaces,

which indicated that a PFC of 0.9 is

fairly typical.

NHTSA notes that AAMA’s claim that

there is worldwide support for

specifying a PFC of 1.0 is incorrect. The

agency notes that when the issue was

discussed by the ECE in the context of

the international harmonization of brake

standards, the decision was to specify a

PFC of 0.9 9. Moreover, when the

Organization International des

Constructeurs d’Automobiles (OICA)

proposed adopting a PFC of 1.0, no

country supported such a requirement.

NHTSA has decided not to adopt

Strait-Stop’s request to specify a

tolerance for the test surface. The

agency notes that in specifying the test

conditions applicable to the test surface,

the agency does not provide a range of

permissible test surfaces. Instead, the

braking standards set forth specific,

objective criteria for the test surface

according to which the agency conducts

its compliance testing.

b. Wheel Lockup Restrictions

In the NPRM, NHTSA proposed that

the straight line stopping distance test

be conducted without locking more than

one wheel per axle or two wheels per

tandem at speeds greater than 20 mph.

In addition, the agency proposed to

allow unlimited lockup at 20 mph or

below, and to allow permissible wheel

lockup for testing purposes. NHTSA

believed that allowing limited wheel

lockup combined with permissible

wheel lockup at speeds above 20 mph

would ensure a safe and reasonably

repeatable test condition, while

providing an indication of a vehicle’s

stability up to the vehicle’s braking

performance limit. These provisions

addressing wheel lockup were based on

the previously mentioned stopping

distance tests conducted at VRTC.

NHTSA requested comments about the

degree to which lockup should be

permitted and under what

circumstances, including whether to

allow unrestricted wheel lockup of test

vehicles.

Commenters addressed four distinct

issues with respect to the wheel lockup

restrictions: (1) Specifying various types

of lockup that would be allowed; (2)

applying the wheel lockup restrictions

to ABS equipped axles; (3) applying the

wheel lockup restrictions to certain

other axles; and (4) applying the wheel

lockup restrictions to emergency system

stops.

AlliedSignal, ATA, AAMA, and

Strait-Stop commented that the wheel

lockup restrictions were not clear.

AlliedSignal suggested that

‘‘permissible’’ and ‘‘limited’’ be

replaced by one term, and that wheel

lockup be defined as 100 percent wheel

slip at both wheels on an axle or more

than two wheels on a tandem for a

duration greater than one continuous

second. AAMA requested that ‘‘wheel

lock restriction’’ be defined ‘‘as 100

percent wheel slip of both wheels of an

axle, or more than two wheels on a

tandem, for a duration greater than one

continuous second.’’ Strait-Stop

requested that permissible wheel lockup

be defined as lockup of one or more

wheels at 100 percent slip for a

reasonable time. ATA stated that the

proposed regulatory language does not

clearly indicate whether unlimited

wheel lockup is permitted at speeds

below 20 mph.

After reviewing these comments,

NHTSA has decided to adopt the

proposed concepts pertaining to wheel

lockup restrictions in the stopping

distance test, with some modifications

to enhance the provision’s clarity. Aside

from defining wheel lockup as 100

percent slip, and renaming ‘‘permissible

wheel lockup’’ as ‘‘momentary wheel

lockup,’’ NHTSA has decided that it is

clearer to specify the concept directly in

the stopping distance requirement in

S5.3.1 instead of defining the various

types of lockup (e.g., momentary

(permissible) lockup, limited lockup,

unlimited lockup) and then referencing

them in S5.3.1. Accordingly, a vehicle is

required to stop with wheel lockup

permitted under the following

conditions. At vehicle speeds above 20

mph, one wheel on any axle or two

wheels on any tandem may lock up for

any duration. At vehicle speeds above

20 mph, wheels on certain axles (i.e.,

nonsteerable axles other than the two

rearmost nonliftable, nonsteerable axles)

may lock up for any duration. At vehicle

speeds above 20 mph, any wheel not

permitted to lock, as described in the

two conditions above, may lock up

repeatedly, with each lockup condition

having a duration of one second or less.

At vehicle speeds of 20 mph or less, any

wheel may lock up for any duration.

These exceptions allowing certain types

of lockup are based on the abovementioned tests conducted at VRTC.

In establishing the requirements

applicable to wheel lockup restrictions,

NHTSA examined the commenters’

recommended definitions for wheel

lockup restriction. The Agency believes

that these definitions achieve only part

of the Agency’s objective in establishing

wheel lockup restrictions. The Agency

interprets AAMA’s definition as

allowing both wheels on an axle to lock

up (100 percent slip) for up to one

second. However, AAMA’s

recommended definition is unclear

about whether one wheel is allowed to

remain locked up for the duration of the

stop. NHTSA believes that it would be

necessary to add additional wording to

AAMA’s definition to achieve the same
Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations 13291

objective that is already achieved by the

Agency’s requirements.

Several commenters stated that the

wheels on any axle controlled by ABS

should be excluded from wheel lockup

constraints. Rockwell International

stated that the proposed stopping

distance regulation will become

obsolete soon, since the references to

permissible and limited wheel lockup

will be superseded by the ABS

regulation. Rockwell WABCO stated

that the proposed stability and control

rulemaking will resolve problems with

respect to the wheel lockup definitions.

AAMA expressed its concern that

imposing wheel lockup constraints on

ABS-equipped vehicles could pose

practicability problems during tests. For

example, AAMA said that the test driver

could be required to modulate brake

pressure in order to prevent wheel

lockup on axles not equipped with ABS,

at the same time the ABS is cycling.

NHTSA believes that the

requirements in S5.3.1 continue to be

necessary, notwithstanding the

Agency’s decision to require heavy

vehicles to be equipped with antilock

brake systems. The Agency believes that

the limited lockup and momentary

lockup restrictions will not impose any

unreasonable or currently unachievable

performance requirement on antilock

systems during the stopping distance

test, since the amount of lockup allowed

by these restrictions is considerably

greater lockup than allowed by any

currently available antilock system. The

antilock requirement specifies that an

ABS on a truck tractor must control ‘‘the

wheels of at least one front axle of the

vehicle and the wheels of at least one

rear axle * * *’’ Therefore, if a vehicle

is equipped with ABS on only one axle

of a rear tandem, the limited and

momentary lockup requirements ensure

that the vehicle can be braked without

excessive wheel lockup of the wheels,

including those controlled by ABS.

Even if both non-ABS-controlled wheels

of the tandem lock for the duration of

the stop (they meet the limited lockup

requirement test), the ABS-controlled

wheels would then be allowed to lock

for a duration of one second or less, at

speeds above 20 mph. The Agency,

therefore, does not agree with the claims

that the backup restrictions would

prohibit ABS on some vehicles, or that

they would pose practicability problems

for test drivers.

NHTSA believes that AAMA’s

concern about problems with specifying

wheel lockup restrictions is unrealistic.

The Agency is unaware of any currently

used antilock system that would allow

wheel lockups that would not comply

with the above restrictions.

Rockwell WABCO further stated that

the wheel lock issue can be resolved by

requiring the vehicle to remain in the

12-foot-wide lane during testing to the

stopping distance requirements.

NHTSA believes that Rockwell

WABCO’s suggestion that the sole

requirement be that a vehicle stay

within a 12-foot-wide lane does not

adequately take into consideration that

on a smooth, flat, and straight surface,

a vehicle with locked wheels might

possibly stay within the lane.

Accordingly, such a stop would not

fully demonstrate the capability of a

vehicle to provide stable stops at the

limit of the vehicle’s braking

performance.

Several commenters recommended

that the wheel lockup restrictions not be

applicable to emergency system stops.

AAMA recommended that wheel lockup

constraints only apply to full service

stops ‘‘to avoid compromises to full

system performance for the sake of

partial system wheel lock.’’

NHTSA agrees with these comments.

In its present form, the restrictions on

wheel lockup in Standard No. 121

appear in S5.3.1, and thus do not apply

to the emergency stops specified in

S5.7.1. The NPRM did not propose to

extend those restrictions to emergency

braking, and the Agency is not making

such a change in this final rule.

c. Control Trailer

In the NPRM, NHTSA proposed two

alternatives for testing a truck tractor in

the loaded condition. The first

alternative proposed the use of a braked

control trailer, which would be similar

to the current braked control trailer. The

second alternative proposed the use of

an unbraked control trailer.

AAMA, ATA, HDBMC and Rockwell

WABCO supported the use of an

unbraked control trailer. They believed

that its use would eliminate many

sources of test result variability and

would produce test results that are

consistent, comparable, and useful.

Rockwell WABCO stated that a braked

control trailer with ABS could lead to

test performance variations since there

are many different trailer antilock

systems now available. It believed that

it would be extremely difficult to define

the required performance of the control

trailer and the antilock system necessary

to have a consistent ‘‘test fixture’’ for the

stopping distance standard.

Strait-Stop objected to the use of an

unbraked control trailer, stating that its

use would render the stopping distance

performance of the combination vehicle

meaningless. Trade International

Corporation (TIC) did not explicitly

support either of the two control trailer

alternatives, but objected to the

mandated use of ‘‘electronically

controlled systems’’ to the exclusion of

any other type of system, for the braked

control trailer ABS.

NHTSA has decided to specify the use

of an unbraked control trailer to test a

truck tractor in the loaded condition.

The Agency notes that this decision,

which is consistent with the views of

most commenters, will eliminate test

variability and produce test results that

are consistent, comparable, and useful.

Contrary to Strait-Stop’s assertion, the

Agency, along with most commenters,

believes that the test results on

unbraked control trailers provide

meaningful comparative information.

This is so because the stopping ability

of all tractors will be evaluated in the

same relative context (i.e., all tractors

would be mated to a similar unbraked

control trailer). An unbraked control

trailer is easier to standardize than a

braked control trailer since there is no

need to specify the foundation brakes

and the antilock brake system. The

section on control trailers in the

stability and control final rule provides

a more extensive discussion of this

issue.

d. Vehicle Loading

In the NPRM, NHTSA proposed that

tractors would be loaded with an

unbraked control trailer, which would

be loaded above the kingpin only, such

that the tractor is at GVWR and the

trailer’s axle is at 4,500 pounds, with

the tractor’s fifth wheel adjusted so that

the load on each axle is proportional to

the axle’s respective GAWR. (See

alternative 2, S6.1.10.4.)

AAMA requested that the Agency add

the phrase ‘‘without exceeding the

GAWR of any tractor or trailer axle.’’

AAMA stated that for some vehicles, it

is impossible to load the tractor to its

GVWR through the kingpin without

exceeding the drive axle GAWR. Due to

limited fifth wheel adjustment on some

vehicles, virtually all of the ballast

added at the fifth wheel is borne by the

tractor’s rear axle, with very little

transferred to the front axle.

After reviewing AAMA’s comment,

NHTSA has decided to amend S6.1.10.4

to include the phrase ‘‘without

exceeding the GAWR of any tractor or

trailer axle.’’ The Agency believes that

this modification is consistent with the

proposal’s intent to have the loading

proportional to each axle’s respective

GAWR. The Agency is aware that this

modification will result in some tractors

being tested slightly below their GVWR.

However, since actual users will be

similarly incapable of loading the

vehicle to its GVWR without exceeding
13292 Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations

10 On August 30, 1993, NHTSA issued an interim

final rule and an NPRM addressing whether the old

burnish procedures should be allowed indefinitely

(58 FR 45459). Optional compliance with the

‘‘new’’ procedures had been permissible since 1988

and was extended to September 1994. The Agency

also proposed extending optional compliance until

March 1996. The Agency requested comments

about whether the new burnish procedures should

become the sole specified procedures or whether

the old burnish procedures should be allowed for

an additional period of time.

11 ‘‘Threshold pressure’’ is the brake application

pressure at which the brakes actually begin to

generate braking torque.

GAWR, the reduced amount should not

adversely affect motor vehicle safety.

e. Initial Brake Temperature

In the NPRM, NHTSA proposed an

initial brake temperature of 250 °F to

300 °F. The Agency tentatively

concluded that specifying a high brake

temperature would reduce cooling time

between stops and therefore allow

vehicle testing to proceed faster. All the

commenters that addressed this issue

opposed the proposed adoption of such

a high initial brake temperature.

Based on these comments and the

available test data, NHTSA has

concluded that an initial brake

temperature of between 150 °F to 200 °F

range is more appropriate than the

proposed temperature range. As

explained in detail in the stability and

control final rule, testing using the 150

°F to 200 °F temperature range is more

repeatable and results in less variation

between runs, compared to testing

conducted at an initial brake

temperature of 250 °F to 300 °F,

particularly for the emergency brake

stops.

f. Emergency Stopping Distance

Requirements

Although the NPRM did not propose

to change the current emergency

stopping distance requirements in

Standard No. 121, several commenters

recommended changes. AMA, ATA,

Allied Signal, HDBMC, and Rockwell

International recommended that the

Agency eliminate the stopping distance

performance requirements for a loaded

truck tractor’s emergency braking

system when tested with an unbraked

control trailer. They stated that a failed

primary or a failed secondary brake

system does not realistically simulate

any real-world vehicle situation that can

occur during a single brake system

failure. They further stated that this

requirement would impose extremely

unrealistic loads on the functioning

truck tractor brakes. AAMA stated that

the emergency brake systems are not

designed to stop a loaded unbraked

control trailer, and that Standard No.

121 already includes a requirement in

S5.7.3(c) stating that a loss of primary or

secondary tractor brakes should not

result in a loss of trailer brakes. Test

data submitted by AAMA and Allied

Signal showed stopping distances in

excess of 2,000 feet for the failed

primary (rear) brakes on a tractor with

a loaded unbraked control trailer. The

stopping test distances submitted for

failed secondary (front) brakes on the

tractor with a loaded unbraked control

trailer were within the current

requirement of 613 feet. Based on these

considerations, the commenters

recommended that the tractor’s

emergency brake system be tested in the

bobtail configuration only.

After reviewing the comments and

other available information, NHTSA has

decided to apply the emergency brake

system test for truck tractors only in the

unloaded (bobtail) condition for both

the failed primary and failed secondary

conditions. According to test data

obtained through the Agency’s testing

and provided by commenters,

emergency brake system testing presents

a unique problem for a loaded truck

tractor with an unbraked control trailer.

With either a primary or secondary

failure of the tractor’s brakes, the loaded

combination would be braked only by

the front axle or rear axle brakes, since

the control trailer is unbraked. As a

result, the stopping distances would be

extremely long, particularly in the case

of the failed rear brakes system. In

addition, such a situation does not

realistically simulate failed truck tractor

systems since in real-world situations,

the trailer brakes are intact.

g. Burnish Procedure

Even though this rulemaking did not

address burnish procedures, AAMA and

HDBMC requested that the Agency

indefinitely allow using the old or the

new burnish procedure as an option.

The Agency believes that the effective

date for the ‘‘new’’ burnish procedure

should be considered in Docket No. 70–

27, Notice 33, and Docket No. 83–07,

Notice 5, independently from the

stopping distance effective dates.10

Given that the industry has been aware

since August 1993 that the new burnish

procedures would be required after

September 1994, NHTSA believes that

vehicle manufacturers have had

sufficient time to conduct any

additional testing and to make any

necessary design changes in order to

meet the requirements of Standard No.

121 with the new burnish procedure.

Moreover, since the new procedures

have been in effect since September 1,

1994, the issue of extending the option

formerly allowed is moot. Therefore,

NHTSA has decided to terminate the

rulemaking on the burnish issue.

h. Parking Brake Test

AAMA requested that the agency

modify the parking brake procedure in

this rulemaking by specifying an initial

brake temperature of 150–200 °F, and a

‘‘compounding technique’’ for

consistency of grade holding and

drawbar procedures. Compounding is

described as a full treadle service brake

application preceding the application of

the parking brakes. AAMA claimed that

during its testing to respond to the

stopping distance NPRMs, it realized

that different manufacturers use

different parking brake test procedures.

Therefore, its stated reason for

proposing a change is to avoid having

compliance issues arise due to alleged

test procedure ambiguities.

NHTSA has neither addressed this

issue in the NPRM nor conducted

research about compounding. Therefore,

the Agency has determined that it

would be inappropriate at this time to

modify the Standard to specify such a

compounding test procedure. If the

Agency were to decide in the future that

it may be desirable to amend the

Standard to require this test condition,

it would issue an NPRM to provide the

industry and other interested parties an

opportunity to comment about such a

modification.

As discussed above, NHTSA has

agreed to AAMA’s request to specify an

initial brake temperature of between

150–200 °F for the service brake

performance tests. As so modified, the

parking brake test procedure explicitly

specifies that the parking brake test be

conducted ‘‘under the conditions of

S6.1,’’ which specifies the initial brake

temperature for the test. Therefore, any

ambiguity that allegedly results from the

higher initial brake temperature is no

longer present.

C. Threshold Pressure Requirement

In the NPRM, NHTSA proposed to

establish a requirement for threshold

pressure 11 levels of 6.0±0.5 psi for truck

tractors and trailers equipped with an

air brake system. The Agency tentatively

concluded that such a requirement

would improve the brake balance on

combination vehicles and reduce the

potential for vehicle instability when

lightly loaded. The Agency requested

comments about the need for

establishing threshold pressures and

whether the proposed threshold

pressure and its range were appropriate

and feasible.

All commenters recognized the need

to improve tractor trailer compatibility
Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations 13293

12 Only Mr. Robert Crail, a brake engineer,

favored adopting a requirement to improve pressure

compatibility between tractors and trailers.

and supported the intent of the

proposed threshold pressure

requirement. However, AAMA,

Midland-Grau, and Rockwell opposed

establishing a threshold pressure

requirement until additional research

could be conducted.12 The commenters

requested that the Agency not issue

such a requirement until a cooperative

industry and government effort can be

conducted to better define the

performance and safety improvements

of a threshold pressure and tolerance

requirement.

Most commenters believed that

selecting a target threshold pressure

value of 6.0 psi, which was approved by

the SAE Brake Committee in 1985,

would not be realistic for current

combination vehicles. In addition,

HDBMC stated that small differences in

threshold pressure are irrelevant to

whether a tractor trailer combination

can achieve the prescribed stopping

distances. HDBMC noted that SAE

Recommended Practice J1505, ‘‘Brake

Force Distribution Test Code’’ (May

1985) was developed primarily to

reduce maintenance costs by improving

brake drum and lining life and to enable

fleets to standardize threshold

pressures. It further stated that the

testing conducted to establish SAE

J1505 was limited to S-Cam brakes and

vehicles with a GAWR of 16,000 to

20,000 pounds. S-Cam brakes on larger

vehicles, wedge brakes (which have

higher threshold pressures) and disc

brakes were not tested.

Several commenters addressed the

threshold pressure level that should be

established if the Agency decided to

adopt a threshold pressure requirement.

Mr. Crail recommended that the

tolerance range be increased from

6.0±0.5 psi to 6.0±1.0 psi to

accommodate the variation in relay

valves, brake chamber return springs

and foundation brake return springs.

AAMA stated that a tolerance for air

brake components of ±3.73 psi was

appropriate. Lucas suggested a tolerance

of +3 psi and that the Agency should

apply this tolerance to only tractor drive

axles and trailer axles with 16.5 inch Scam drum brakes. ATA recommended a

tolerance of between 2 to 11 psi.

After reviewing the comments and

other available information, NHTSA has

decided not to establish a pressure

threshold requirement at this time. The

Agency notes that additional research

and testing needs to be conducted on

this matter since there currently is

insufficient information to set a

threshold pressure tolerance for

combination vehicles. The brake

components that affect the threshold

pressure, such as internal friction in the

relay valves and the return springs in

the brake chamber and foundation

brakes, provide a tolerance close to 4

psi. Therefore, establishing a threshold

pressure requirement, even with a broad

tolerance, could pose compliance

problems for the industry. In addition,

additional research needs to be

conducted on brakes other than S-cam

brakes.

NHTSA emphasizes that after

additional cooperative testing is

completed, a threshold pressure

requirement could be proposed that

would improve the braking performance

of a combination vehicle, particularly at

low application pressures typical of

normal stops.

D. Requirements for Brake Linings

ATA and Mack Trucks requested that

NHTSA issue a rule requiring

replacement brake linings to be of the

same quality and have the same friction

characteristics as the linings used by

original equipment manufacturers.

The issue of aftermarket brake linings

is the subject of a separate NHTSA

rulemaking action, and will not be

addressed by this notice. If the Agency

tentatively concludes that such

requirements for aftermarket brake

linings are in the interest of motor

vehicle safety, then it will issue a

proposal to adopt such requirements.

E. Implementation Schedule

In the NPRM, NHTSA proposed that

the stopping distance requirements

become effective two years after the

final rule’s publication.

AAMA supported the proposed

effective date, provided that the agency

incorporated its recommended

modifications in the final rule. Rockwell

recommended that the stopping

distance requirements and the stability

performance requirements be combined

so that the effective dates for both

rulemakings are concurrent. Several

commenters on the stability and control

NPRM, including AAMA, made the

same suggestion. AAMA noted that

since ABS can directly influence

achievable stopping distance, it is

important to optimize brake system

performance by taking both stopping

distance and stability into account.

On April 12, 1994, NHTSA published

a supplemental notice of proposed

rulemaking that proposed the following

implementation schedule for both the

stopping distance and lateral stability

and control requirements:

Truck tractors—2 years after final rule

(1996)

Trailers—3 years after final rule (1997)

Air-braked single unit trucks and

buses—3 years after final rule (1997)

Hydraulic-braked single unit trucks and

buses—4 years after final rule (1998).

(59 FR 17326).

The Agency reasoned that making the

effective dates for the two rulemakings

concurrent would promote a more

orderly implementation process, avoid

the need for manufacturers to redesign

the brakes on individual vehicles twice,

and reduce the development and

compliance costs that manufacturers

would face as a result of these

regulations. NHTSA requested

comments about the implementation

schedule proposed in the supplemental

notice.

As the stability and control final rule

discusses in detail in the section titled

‘‘implementation schedule,’’ NHTSA

has decided to adopt an implementation

schedule similar to the one proposed in

the SNPRM. Specifically, truck tractors

manufactured on or after March 1, 1997

will have to be equipped with ABS and

comply with the braking-in-a-curve test

and high coefficient of friction stopping

distance requirements; trailers and

single-unit air-braked trucks and buses

manufactured on or after March 1, 1998

will have to be equipped with ABS, and,

except for trailers, comply with the high

coefficient of friction stopping distance

requirements; and hydraulic-braked

trucks and buses manufactured on or

after March 1, 1999 will have to be

equipped with ABS and comply with

the high coefficient of friction stopping

distance requirements. The Agency has

decided that these effective dates, which

were widely supported by vehicle

manufacturers, brake manufacturers,

and safety advocacy groups, will

provide for an efficient implementation

of the heavy vehicle braking

rulemakings.

F. Intermediate and Final Stage

Manufacturers/Trailer Manufacturers

Vehicle manufacturers must certify

that each of their vehicles complies with

all applicable Federal motor vehicle

safety standards. While this statutory

certification requirement is

straightforward with respect to vehicles

produced by a single manufacturer, it is

more complex for vehicles produced in

two or more stages. With such

multistage vehicles, one or more

manufacturers produce an ‘‘incomplete

vehicle’’ which requires further

manufacturing operations by another

manufacturer to become a completed

vehicle. As defined in 49 CFR 568.3, an

incomplete vehicle includes, at a
13294 Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations

13 In today’s Federal Register notice amending

Standard No. 105 with respect to stopping distances

of hydraulically-braked vehicles, the Agency is also

modifying that Standard to include identical

language about compliance by final stage

manufacturers so that this concept expressly

applies to hydraulic-braked vehicles manufactured

in two or more stages, as well.

minimum, a frame and chassis

structure, power train, steering system,

suspension system, and braking system.

Incomplete vehicles may be grouped in

two categories: (1) Chassis-cabs (which

are incomplete vehicles with fully

completed occupant compartments that

require only the addition of cargocarrying, work-performing, or loadbearing components to perform their

intended functions and become

completed vehicles (49 CFR 567.3))

which are certified by the chassis-cab

manufacturer (49 CFR 567.5), and (2)

incomplete vehicles other than chassiscabs (‘‘non chassis-cabs’’), which are not

certified by the incomplete vehicle

manufacturer.

The National Truck Equipment

Association (NTEA) commented that

manufacturers of multi-stage vehicles

may not be able to demonstrate

compliance with the proposed

amendments because they may not be

able, in all cases, to ‘‘pass through’’ the

incomplete vehicle manufacturer’s

certification. NTEA claims that these

manufacturers will not have a

practicable and objective means of

demonstrating compliance, since they

lack the financial resources and

capabilities to sponsor testing to the

requirements. Therefore, NTEA

suggested that the Agency exclude

multi-stage vehicles from the proposed

road testing requirements.

As explained below, NHTSA has

concluded that the stopping distance

requirements do not pose an

unreasonable burden for final stage

manufacturers. NHTSA is aware of the

concerns of final stage manufacturers

about road testing their vehicles.

However, the final stage manufacturers

can avoid the necessity of conducting

independent testing by staying within

the limits (‘‘the envelope’’) set by the

incomplete vehicle manufacturer. In

fact, S6 of Standard No. 121 currently

provides that ‘‘Compliance of vehicles

manufactured in two or more stages

may, at the option of the final-stage

manufacturer, be demonstrated to

comply with this standard by adherence

to the instructions of the incomplete

manufacturer provided with the vehicle

in accordance with § 568.4(a)(7)(ii) and

§ 568.5 of title 49 of the Code of Federal

Regulations.’’13 In the final rule adding

this provision in response to the 9th

Circuit’s decision in PACCAR, the

Agency stated that it provides directly

in the regulation ‘‘an alternative to road

testing * * * that would constitute ‘due

care’ in certification by any final-stage

manufacturer that adopted it, whatever

its resources and engineering expertise.’’

(43 FR 48646, October 19, 1978.)

With respect to chassis-cabs, the name

of each manufacturer in the chain of

production is required to appear on one

or more certification labels that are

permanently affixed to the vehicle. (49

CFR Parts 567 and 568.) Under these

regulations, certification of an

incomplete vehicle that is a chassis-cab

can ‘‘pass through’’ to the final stage

manufacturer, provided that the final

stage manufacturer takes the

precautions necessary to ensure it does

not invalidate the certification. The final

stage manufacturer must ensure that it

completes the vehicle without

exceeding the GVWR and GAWRS

assigned by the chassis-cab

manufacturer, altering any brake system

component, moving the center of gravity

of the completed vehicle with the body

installed outside the ‘‘envelope’’ of

specifications provided by the chassis

manufacturer, or otherwise violating

that envelope. If the final stage

manufacturer complies with all of the

chassis-cab manufacturer’s

specifications, the final stage

manufacturer can base its certification

of compliance with the braking standard

entirely upon the statement of the

chassis-cab manufacturer and therefore

will not have to recertify the vehicle.

The provision in S6 also applies to

non-chassis-cabs, since the

manufacturer of a non-chassis-cab is

required to furnish documentation that

indicates a means of compliance with

applicable standards to intermediate or

final stage manufacturers (49 CFR

568.4), and the final stage manufacturer

is required to identify the incomplete

manufacturer on the certification label

that the final stage manufacturer places

on the completed vehicle. As with

chassis-cabs, the final stage

manufacturer can avoid the necessity of

conducting independent testing by

staying within the envelope set by the

incomplete manufacturer.

Based on the above considerations,

the final stage manufacturer would only

be required to certify compliance

independently in those cases in which

the final vehicle violates those

specifications. NTEA commented that

there are situations in which the final

stage manufacturer ‘‘must exceed the

‘envelope’ of restrictions provided by

the chassis manufacturer due to

customer specifications.’’ The Agency

believes that in virtually all such cases

the body or equipment that is specified

by the customer could be fitted on a

different truck chassis having a larger

‘‘envelope’’. Moreover, when the

customer has an overriding need to

specify a particular truck chassis that

cannot be completed with the desired

body or equipment without exceeding

the envelope, it is reasonable to expect

the customer to bear the additional cost

burden of assuring that the completed

vehicle complies with the standard. In

such situations, it is reasonable to

require the final stage manufacturer to

accept responsibility for certification,

given the important safety concerns

discussed below. The Agency

emphasizes, however, that it is not

necessary for final stage manufacturers

to make this choice. They can instead

select an appropriate incomplete vehicle

that can be completed without departing

from the envelope specified by the

incomplete vehicle manufacturer.

Some of the manufacturers that build

multi-stage vehicles and choose not to

stay within the envelope are small

businesses that may be unable to

conduct their own road tests. While

manufacturers must certify that their

vehicles meet all applicable safety

standards, this does not mean that every

final stage manufacturer must

independently conduct the specific tests

set forth in an applicable standard. A

final stage manufacturer may also certify

compliance to the stopping distance

standard based on, among other things,

engineering analyses and computer

simulations. Moreover, manufacturers

need not conduct these operations

themselves. They can utilize the

services of independent engineers and

testing laboratories. They can also join

together through trade associations to

sponsor testing or analysis. Finally, they

can rely on testing and analysis

performed by other parties, including

brake manufacturers. Brake

manufacturers typically perform

extensive analyses and tests of their

products and, in order to sell those

products, have a strong incentive to

provide their customers, the vehicle

manufacturers, with information that

can be used to certify the vehicle to the

applicable brake standards. Some

manufacturers of motor vehicle

components currently provide this type

of information to vehicle manufacturers.

Based on the above considerations,

NHTSA has concluded that

manufacturers can certify compliance

with the stopping distance requirements

by means other than road testing.

Moreover, road testing to establish

compliance with the braking

requirements does not involve

expensive and destructive crash testing,

which cost $18,000 or more, not
Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations 13295

14The basic methodology used to convert injuries

at various levels of severity into equivalent fatalities

is outlined in the FEA for this final rule.

including the cost of the vehicle which

is destroyed as a result of the test. Thus,

while brake testing does involve some

expense (the Agency estimates that a

complete compliance test series for

Standard No. 121 would cost $5,000), it

should be feasible for manufacturers,

including small manufacturers

(especially in groups or through

associations), to certify compliance,

particularly since the road testing does

not require destruction of their vehicles.

Furthermore, NHTSA is not

authorized when establishing safety

standards to differentiate between

manufacturers on the basis of their size

or financial resources. While the agency

must ‘‘consider whether any such

proposed standard is reasonable,

practicable and appropriate for the

particular type of motor vehicle or

motor vehicle equipment for which it is

prescribed,’’ (49 U.S.C. 30111(b)(3),

formerly section 103(f)(3) of the Vehicle

Safety Act), the legislative history of the

Vehicle Safety Act reveals that any

differences between standards for

different classes of vehicles ‘‘of course

[are to] be based on the type of vehicle

rather than its place of origin or any

special circumstances of its

manufacturer.’’ S. Rept. 1301, 2 U.S.

Code, Cong. & Admin. News, 2714

(1966), cited in Chrysler Corp. v. D.O.T.,

472 F.2d 659, 679 (6th Cir. 1972).

Strong policy reasons underlie

Congress’ refusal to differentiate

between vehicles on the basis of the

manufacturers’ ‘‘special circumstances.’’

To protect unsuspecting members of the

public from exposure to unreasonable

risks posed by unsafe vehicles, there is

good reason to require that every vehicle

meet all ‘‘minimum performance

standards’’ that are prescribed for

vehicles of its type.

Moreover, the statute does not

authorize NHTSA to grant permanent

exemptions from safety standards to

small manufacturers who otherwise

would be covered by those standards.

See Nader v. Volpe, 475 F.2d 916, 918

(D.C. Cir. 1973). While Nader involved

a single manufacturer that sought to be

permanently exempted from safety

standards, its reasoning applies equally

to classes of manufacturers that seek

such exemptions. Although the Safety

Act was amended after the Nader

decision to permit small manufacturers

to seek temporary exemptions from

safety standards if they can demonstrate

that compliance with the standard

would cause them ‘‘substantial

economic hardship’’ and that they have

made a good faith effort to comply (49

U.S.C. 30113, formerly section 123 of

the Vehicle Safety Act), Congress has

severely restricted the agency’s

authority to grant such exemptions to

very narrow, limited circumstances.

NTEA is in effect seeking a permanent

exemption from Standard No. 121 that

the statute does not permit.

NHTSA emphasizes that there are

important safety reasons that necessitate

having a final stage manufacturer certify

the completed vehicle if it does not stay

within the envelope set by the

incomplete vehicle manufacturer. For

instance, if a final stage manufacturer

adds additional components so that the

completed vehicle’s GVWR exceeds the

recommended maximum GVWR weight

specified in the envelope for the

vehicle, the vehicle’s braking

performance could be adversely

affected. As an example, a brake system

designed to bring a 15,000 pound

vehicle to a stable and short stop would

obviously not be able to safely stop a

20,000 pound vehicle. Moreover, the

brakes on such an underbraked vehicle

would be prone to overheating. While it

is relatively easy to understand the

degradation in performance in such a

gross example, the potential for

reduced, safety-related performance also

exists in situations were the ‘‘violation’’

of the envelope is much smaller.

Similarly, if the center of gravity is

made too high, a vehicle would likely be

overbraked on its rear axle(s) and thus

be prone to instability caused by wheel

lockup.

NHTSA emphasizes that the kinds of

crashes that result when a heavy vehicle

is unable to stop to avoid another

vehicle are very serious. As part of the

cost effectiveness analysis contained in

the Final Economic Analysis (FEA) for

this final rule, the agency used 1992

GES data to identify a group of crashes

involving heavy vehicles defined as

‘‘unable-to-stop-in-time’’ crashes. The

agency examined these crashes and the

number and severity of the resulting

injuries in evaluating the impact of this

regulation. One means of comparing the

relative severity of various types of

crashes is to ‘‘convert’’ the injuries at

different levels of severity into

‘‘equivalent fatalities’’ 14 and to divide

that by the number of crashes that

resulted in those injuries. The resulting

ratio, equivalent fatalities per crash, can

be calculated for various types of

crashes and compared to indicate the

relative severity of different crash types.

Using 1992 GES data, estimates were

made of the equivalent fatalities per

crash for multiple-vehicle crashes

involving all types of vehicles, 0.01402

equivalent fatalities per crash, for

multiple-vehicle crashes involving

heavy vehicles, 0.02089 equivalent

fatalities per crash, and for the ‘‘unableto-stop-in-time’’ crashes mentioned

above, 0.03634. Comparing the rates of

equivalent fatalities indicate that not

only are multiple-vehicle crashes

involving heavy vehicles 49% more

severe than all multiple-vehicle crashes,

but the ‘‘unable-to-stop-in-time’’

crashes, which are the types of crashes

affected by this final rule, are 159%

more severe than all multiple-vehicle

crashes in general. Also using 1992 GES

data, the agency made separate

estimates of the rate of equivalent

fatalities per crash for the heavy vehicle

occupants and the occupants of other

involved vehicles. This was done for

both multiple-vehicle crashes involving

heavy vehicles and for the ‘‘unable-tostop-in-time’’ crashes. The comparison

of these rates shows that the ‘‘unable-tostop-in-time’’ crashes are 31% more

severe in terms of injuries to the heavy

vehicle occupant and 79% more severe

for the occupants of other involved

vehicles than multiple-vehicle crashes

involving heavy vehicles.

G. Costs

As explained in detail in the FEA, the

costs associated with the rulemaking

involve additional testing costs and

hardware/equipment costs. The agency

estimates the minimum initial testing

costs associated with reinstating

stopping distance requirements for all

heavy air-braked vehicles would be

about $6 million. As noted in the FEA,

the estimated annual compliance testing

costs in years following the effective

dates of this final rule are estimated to

be about $2 million. Assuming the

industry continues to produce about

208,500 heavy Class 5–8 air-braked

vehicles per year (which are the largest

heavy vehicles and tractor trailers), the

initial testing cost per vehicle would be

about $29 and for later years the testing

cost per vehicle would be about $10.

The hardware and equipment costs of

meeting the proposed stopping distance

requirements for air braked heavy

vehicles are based on the anticipated

improvements to heavy vehicles. The

agency notes that all of the changes

made to meet these requirements would

affect vehicles operating in the fully

loaded, or nearly fully loaded

configurations.

These improvements in braking

performance, which are achieved by

substituting air chambers, slack

adjusters and brake linings, are

estimated to be necessary on about

104,000 air-braked vehicles, including

both truck tractors and single-unit

trucks. The average cost per vehicle of
13296 Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations

these changes is estimated to be $50,

resulting in a total cost of $5.21 million,

which is the total estimated cost for

vehicle modifications necessitated by

this final rule.

The total estimated initial cost impact

of this proposal is $11.21 million ($6.0

million in compliance test costs plus

$5.21 million in vehicle modification

costs), which for an estimated annual

production of 208,500 air-braked

equipped vehicles, is an average of

about $54 per vehicle.

The total estimated outyear cost

impact of this proposal is $7.21 million

($2.0 million in compliance test costs

plus $5.21 million in vehicle

modification costs), which for an

estimated annual production of 208,500

air braked equipped vehicles, is an

average of about $35 per vehicle.

VI. Rulemaking Analyses and Notices

A. Executive Order 12866 and DOT

Regulatory Policies and Procedures

This rulemaking document was not

reviewed under E.O. 12866. NHTSA has

considered the impact of this

rulemaking action under the

Department of Transportation’s

regulatory policies and procedures. This

action has been determined to be not

‘‘significant’’ under those policies and

procedures.

A FEA setting forth the agency’s

detailed analysis of the benefits and

costs of this rulemaking (along with the

other rules issued today) has been

prepared and been placed in the docket.

This rulemaking is based on the FEA

and all additional data available to the

agency. The Agency estimates that

reinstating the stopping distance

requirements for Standard No. 121 will

result in an average of approximately

3.2 lives saved per year and 84 injuries

prevented per year. As mentioned

above, the agency estimates that the

initial annual costs attributable to these

requirements are approximately $11.21

million ($6.00 million for compliance

testing and $5.21 million for net

equipment costs) and the outyear

annual costs attributable to these

requirements are approximately $7.21

million ($2.00 million for compliance

testing and $5.21 million for net

equipment costs).

Based on its analysis, the agency

concludes that the requirements will

improve safety by ensuring that all

heavy vehicles are capable of stopping

within a specified, safe distance. Based

on information detailed in the previous

section, the agency believes that

implementing the stopping distance

requirements for heavy vehicles will not

result in significant costs since most of

these vehicles currently comply with

the reinstated requirements. For those

vehicles that do not currently comply

with the requirements, the agency

believes that they could be upgraded by

substituting other with currently

produced braking components for those

now used on these vehicles.

Since these components are not

significantly more expensive than those

used in poorer performing brake

systems, the net cost of substituting

these components will not be significant

and is estimated to be about $50 for

each vehicle that requires such changes.

B. Regulatory Flexibility Act

NHTSA has also considered the

impacts of this notice under the

Regulatory Flexibility Act. I hereby

certify that this rule will not have a

significant economic impact on a

substantial number of small entities.

There may be a small number of

intermediate and final stage

manufacturers that are small businesses

that may be impacted by this final rule,

but as discussed previously, the Agency

does not believe that that impact is

substantial, particularly in comparison

to the possible crash-related

consequences of vehicles produced by

such manufacturers not complying with

the rule.

C. Paperwork Reduction Act

In accordance with the Paperwork

Reduction Act of 1980 (P.L. 96–511),

there are no requirements for

information collection associated with

this rule.

D. National Environmental Policy Act

NHTSA has also analyzed this rule

under the National Environmental

Policy Act and determined that it will

not have a significant impact on the

human environment. No changes in

existing production or disposal

processes will result, except that there

is a reduction in these factors resulting

from the removal of the ALV. There will

be a weight increase of a few pounds per

tractor with the installation of a BPV on

tractors, but such a small increase

should not have any significant effect on

fuel consumption. Nor should

production and disposal processes have

a significant adverse affect on the

environment.

E. Executive Order 12612 (Federalism)

NHTSA has analyzed this rule in

accordance with the principles and

criteria contained in E.O. 12612, and

has determined that this rule will not

have significant federalism implications

warranting the preparation of a

Federalism Assessment.

F. 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, this

notice amends 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.

§ 571.121 [Amended]

2. Section 571.121, is amended by

removing the undesignated text

following paragraph (g) in S3; in S4 by

adding the definition for ‘‘Wheel

lockup;’’ by revising S5.3.1, S5.3.1.1,

and Table II; by deleting S5.3.2,

S5.3.2.1, and S5.3.2.2; by reserving

S5.3.2, and by revising S5.7.1 to read as

follows:

* * * * *

Wheel lockup means 100 percent

wheel slip.

* * * * *

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:
Federal Register / Vol. 60, No. 47 / Friday, March 10, 1995 / Rules and Regulations 13297

(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 with vehicle at gross vehicle

weight rating:

Table I.—Stopping Sequence—

Continued

(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) 30 mph service brake stops on a peak

friction coefficient surface of 0.5, for a

truck tractor with a loaded unbraked

control trailer.

(c) 60 mph emergency brake stops 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) 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) 30 mph service brake stops on a peak

friction coefficient surface of 0.5, for a

truck tractor.

Table I.—Stopping Sequence—

Continued

(c) 60 mph emergency brake stops 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.

S5.3.1.1 Stop the vehicle from 60

mph on a surface with a peak friction

coefficient of 0.9 with the vehicle

loaded as follows: (a) loaded to its

GVWR, (b) in the Bobtail configuration

(truck-tractors only) plus up to 500

pounds, and (c) at its unloaded vehicle

weight (except for a truck tractor) plus

up to 500 pounds (including driver and

instrumentation). If the speed attainable

in two miles is less than 60 mph, the

vehicle shall stop from a speed in Table

II that is 4 to 8 mph less than the speed

attainable in 2 miles.

TABLE II.—STOPPING DISTANCE

[In feet]

Vehicle speed in miles per hour

Service

brake

Emergency

brake

PFC

0.9

PFC

0.9

PFC

0.9

PFC

0.9

PFC

0.9

PFC

0.9

(1) (2) (3) (4) (5) (6)

20 ...................................................................................................................................... 32 35 38 40 83 85

25 ...................................................................................................................................... 49 54 59 62 123 131

30 ...................................................................................................................................... 70 78 84 89 170 186

35 ...................................................................................................................................... 96 106 114 121 225 250

40 ...................................................................................................................................... 125 138 149 158 288 325

45 ...................................................................................................................................... 158 175 189 200 358 409

50 ...................................................................................................................................... 195 216 233 247 435 504

55 ...................................................................................................................................... 236 261 281 299 520 608

60 ...................................................................................................................................... 280 310 335 355 613 720

Note: (1) Loaded and unloaded buses; (2) Loaded single unit trucks; (3) Unloaded truck tractors and single unit trucks; (4) Loaded truck tractors tested with an unbraked control trailer; (5) All vehicles except truck tractors; (6) Unloaaded truck tractors.

* * * * *

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.

* * * * *

Issued on: March 1, 1995.

Ricardo Martinez, M.D.

Administrator.

[FR Doc. 95–5413 Filed 3–7–95; 8:45 am]

BILLING CODE 4910–59–P

49 CFR Part 571

[Docket No. 93–07; Notice 3]

RIN 2127–AE21

Federal Motor Vehicle Safety

Standards; Stopping Distance

Requirements for Vehicles Equipped

With Hydraulic Brake Systems

AGENCY: National Highway Traffic

Safety Administration (NHTSA),

Department of Transportation.

ACTION: Final rule.

SUMMARY: This final rule establishes

stopping distance performance

requirements in Standard No. 105,

Hydraulic Brake Systems, for trucks,