[Federal Register Volume 64, Number 36 (Wednesday, February 24, 1999)]
[Proposed Rules]
[Pages 9115-9118]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-4522]


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

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA-99-5114]
RIN 2127-AH31


Federal Motor Vehicle Safety Standards: Light Vehicle Brake 
Systems

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

ACTION: Termination of rulemaking.

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

SUMMARY: This action terminates rulemaking initiated by the agency's 
granting of a petition for rulemaking submitted by the American 
Automobile Manufacturers Association (AAMA) concerning the Federal 
motor vehicle safety standard on light vehicle brake systems. The 
standard currently uses data from the cold effectiveness tests to 
establish performance levels for the ``hot performance'' and ``recovery 
performance'' test requirements. AAMA requested use of a different 
procedure for establishing these performance levels, which would be 
based on three new constant deceleration stops.
    The agency has decided to terminate this action because the 
procedures AAMA requested would not assess the effect of heat on light 
vehicle braking systems any more accurately or repeatably than the 
procedures currently specified in the standard. In addition, the 
procedures currently specified in the standard are presently harmonized 
with the procedures in the counterpart standard established by the 
United Nation's Economic Commission for Europe (ECE) for light vehicle 
brake systems. Absent sufficient safety reason to change the existing 
procedure, and considering that such a change would move NHTSA's 
standards away from harmony with the ECE standards, the agency has 
decided to terminate its consideration of the requested change.


[[Page 9116]]


FOR FURTHER INFORMATION CONTACT:
    For technical issues: Mr. Samuel Daniel, Jr., Safety Standards 
Engineer, Office of Crash Avoidance Standards, Vehicle Dynamics 
Division, 400 Seventh Street, SW, room 5307, Washington, DC 20590; 
telephone (202) 366-2720; fax (202) 493-2739.
    For legal issues: Mr. Walter Myers, Attorney-Advisor, Office of the 
Chief Counsel, National Highway Traffic Safety Administration, 400 
Seventh Street, SW, room 5219, Washington, DC 20590; telephone (202) 
366-2992; fax (202) 366-3820.

SUPPLEMENTARY INFORMATION:

A. Background

1. Regulatory History

    On February 2, 1995, NHTSA published in the Federal Register (60 FR 
6411) a final rule establishing Federal Motor Vehicle Safety Standard 
No. 135, Passenger car brake systems. This new standard replaced 
Standard No. 105, Hydraulic and electric brake systems, insofar as it 
applied to passenger cars.
    On September 30, 1997, the agency published in the Federal Register 
(62 FR 51064) a final rule extending the new standard to trucks, buses 
and multipurpose passenger vehicles with a gross vehicle weight rating 
(GVWR) of 3,500 kilograms (7,719 pounds) or less. The name of the 
standard is now Standard No. 135, Light vehicle brake systems.
    Standard No. 135 resulted from the agency's efforts to harmonize 
its hydraulic brake standard with ECE standards. The agency believed 
that the new standard would promote the goal of international 
harmonization while remaining consistent with the statutory mandate to 
ensure motor vehicle safety.
    Among other requirements, the new standard specifies a ``cold 
effectiveness'' test which is intended to test the vehicle's ability to 
come to a quick, controlled stop with all braking systems functional, 
simulating emergency stopping in real-world driving. In this test, the 
vehicle is required to stop within 70 meters from a speed of 100 km/h 
with a brake pedal force that does not exceed 500 Newtons. Six ``best-
effort'' stops are performed for this test; in at least one of the six 
stops, the vehicle must meet the 70-meter stopping distance 
requirement.
    The standard also requires a ``hot performance'' and a ``recovery 
performance'' test sequence. The purpose of these tests is to ensure 
adequate braking capability during and after exposure to the high brake 
temperatures caused by prolonged or severe use. Examples of such severe 
use include mountain descents and severe stop-and-go driving. Heat 
affects the performance of the foundation brake system components, 
often resulting in longer stopping distances.
    The hot performance test specifies a percentage limit on 
degradation from the performance achieved in the cold effectiveness 
test. This controls the amount of reduction in performance that a 
vehicle experiences when the brakes are heated.
    The recovery performance test places both lower and upper limits on 
the difference between the stopping distance achieved after several 
normal brake applications immediately following the hot performance 
test and the distance achieved in the cold effectiveness test. The 
lower limit controls the amount of degradation, while the upper limit 
ensures that brakes do not become too sensitive when heated and ``over-
recover.''
    As noted above, the stopping performance for both the hot stop and 
recovery performance tests is based on the performance achieved in the 
cold effectiveness test. The average pedal force used during the cold 
effectiveness test establishes the allowable average pedal force (and 
thus the stringency) for the hot performance test and the recovery 
performance test. S7.14 of Standard No. 135, Hot Performance, requires 
a vehicle with heated brakes to be capable of achieving at least 60 
percent of the deceleration obtained during the best cold effectiveness 
stop, with an average pedal force that does not exceed the average 
pedal force recorded during that cold effectiveness stop. S7.16, 
Recovery Performance, requires the vehicle to be capable of achieving 
between 70 percent and 150 percent of the deceleration obtained during 
the best cold effectiveness stop, with an average pedal force that does 
not exceed the average pedal force used during that cold effectiveness 
stop.

2. AAMA Petition

    The AAMA submitted a petition for rulemaking requesting that NHTSA 
amend Standard No. 135 to add 3 constant deceleration stops at the 
beginning of the thermal test sequence to establish baseline 
performance for the hot and recovery tests, rather than using the 
results of the current cold effectiveness test to establish such 
baseline performance.
    In its petition, AAMA noted that General Motors (GM) had previously 
requested an interpretation from the agency concerning ``the pedal 
force that may or must be used during cold effectiveness testing of ABS 
[antilock brake systems] equipped vehicles for purposes of establishing 
allowable pedal force for thermal testing.'' In its May 16, 1996 
response, NHTSA stated:

    We anticipate that test drivers will utilize a variety of pedal 
forces during the six cold effectiveness stops in an effort to 
achieve the shortest possible stopping distance consistent with the 
test procedures. The average pedal force that resulted in the 
shortest stopping distance of these six tests would be used to 
ascertain compliance with the thermal and recovery performance 
requirements under S7.14 and S7.16. If, as you suggest, the shortest 
distance can be achieved at more than one average pedal force level 
(e.g., if the ABS cycles at a variety of pedal forces below 500 
Newtons, or the test driver is able to modulate braking forces to 
avoid wheel lock while matching the stopping performance of the ABS 
system), the vehicle must be capable of satisfying the thermal and 
recovery performance requirements at all such average pedal force 
levels.

    In a subsequent meeting with the agency, GM indicated that it 
believed it is impractical for test drivers to determine both the 
minimum achievable stopping distance and the minimum pedal force that 
can provide that stopping distance within the six stops prescribed for 
cold effectiveness testing. It argued that this ``practicability'' 
problem is most acute for vehicles fitted with ABS. GM stated that the 
best resolution would be an amendment to Standard No. 135 adding 
constant deceleration stops at the beginning of the thermal test 
sequence in order to establish performance requirements for the 
subsequent hot and recovery tests.

B. Discussion

    The concerns identified by GM ultimately led AAMA to submit its 
petition for rulemaking. AAMA's arguments and the agency's responses 
can be summarized as follows:
    a. The requested amendments would promote international 
harmonization by more closely aligning Standard No. 135 with its 
European counterpart, ECE Regulation R13-H. The European approach is to 
use constant pedal force applications to determine braking performance, 
including cold effectiveness capability. This contrasts with the U.S. 
approach of using an initial pedal force spike during cold 
effectiveness tests in order to minimize the response time of the 
system, thereby minimizing stopping distance. These requested 
amendments would reduce that disparity.
    NHTSA: The agency disagrees with the AAMA statement. A review of 
R13-H test procedures indicates that a constant pedal force application 
is not specified in European Type-O tests,

[[Page 9117]]

which specify test procedures nearly identical to the cold 
effectiveness test procedures of Standard No. 135. Although test 
drivers in Europe may use different techniques than those in the U.S., 
those techniques are within the test parameters to achieve the best 
stop with a pedal force of 500 Newtons or less. Thus, they should not 
be considered disparate. The agency believes that all other hot and 
recovery test procedures and performance requirements in R13-H are 
sufficiently harmonized with Standard No. 135.
    In addition, the harmonization of Standard No. 135 and ECE R13-H 
would be adversely affected because the ECE brake standard group, the 
Meeting of Experts on Brakes and Running Gear (GRRF), has shown no 
interest in modifying R13-H to be consistent with the AAMA proposal. A 
review of test data generated by the GRRF during the development and 
coordination of ECE R13-H and FMVSS No. 135 indicated that constant 
deceleration stop tests similar to the tests proposed by AAMA were 
difficult to execute. There was also considerable disagreement among 
European researchers on the appropriate deceleration rate for the tests 
and the number of test runs to require in the regulation.
    b1. AAMA: The requested amendment would resolve a practicability 
problem presented by the current test provisions of Standard No. 135. 
The standard currently bases hot and recovery deceleration performance 
requirements and pedal force constraints to the best cold effectiveness 
stop. It is not possible for test drivers to determine with certainty 
that they have achieved both the shortest possible stopping distance 
and the minimum pedal force that will provide the specified stopping 
distance within the 6 cold effectiveness stops, especially for vehicles 
equipped with ABS.
    NHTSA: The stopping distance procedure specified in S6.5.3.2 
requires that the test vehicle be stopped in the shortest distance 
achievable on all stops. There is no requirement for the test driver to 
use the minimum pedal force to achieve the best stop.
    The agency adheres to its previous position that if the shortest 
stopping distance can be achieved at more than one average pedal force, 
the vehicle must be capable of satisfying the hot and recovery 
performance test requirements at all such average pedal force levels.
    The agency conducted most of the cold effectiveness tests during 
the development of FMVSS No. 135 using a constant 500 N pedal force. 
Recent compliance tests indicate that, as AAMA stated in its petition, 
the average pedal force can vary considerably for the six (6) cold 
effectiveness stopping tests with small variations in stopping 
distance. However, all tested vehicles complied with the hot and 
recovery performance requirements based on cold effectiveness test 
results, as follows:

------------------------------------------------------------------------
                                                               Stopping
               Average pedal force  (Newtons)                  distance
                                                               (Meters)
------------------------------------------------------------------------
Vehicle A:
  307......................................................           60
  302......................................................           57
  319......................................................           58
  364......................................................           57
  388......................................................           59
  412......................................................           54
Vehicle B:
  130......................................................           65
  297......................................................           52
  346......................................................           52
  316......................................................           53
  402......................................................           51
  372......................................................           52
Vehicle C:
  197......................................................           51
  424......................................................           48
  350......................................................           46
  330......................................................           48
  453......................................................           47
  361......................................................           47
Vehicle D:
  301......................................................           57
  328......................................................           51
  376......................................................           54
  386......................................................           54
  407......................................................           53
Vehicle E:
  379......................................................           53
  234......................................................           55
  314......................................................           52
  340......................................................           52
  368......................................................           50
Vehicle F:
  366......................................................           46
  337......................................................           47
  388......................................................           47
  298......................................................           49
  313......................................................           50
  280......................................................           48
------------------------------------------------------------------------

    Note: The agency does not have a reading for the 6th stop on 
Vehicles D and E.)

    b2. AAMA: The current language of the standard almost guarantees 
that the cold effectiveness deceleration and pedal force combination 
results obtained by a manufacturer will be different from the results 
obtained by NHTSA in an enforcement test of the same vehicle model. 
This disparity will be magnified in subsequent hot and recovery results 
since the manufacturer and NHTSA will be operating with different pedal 
force constraints and performance requirements.
    NHTSA: The test procedures require best effort on all runs 
(S6.5.3.2) with only six (6) runs to achieve the shortest stopping 
distance in the cold effectiveness test. Thus, NHTSA believes that 
there will be little variation in the stopping techniques used by test 
drivers. The degradation of the brake system as a function of heat, as 
well as the allowable pedal force value, is a key factor in determining 
compliance with the hot and recovery performance requirements. As 
stated above, the agency believes that the hot and recovery performance 
should comply with the requirements at any pedal force that produces 
the shortest stopping distance in the cold effectiveness test. The cold 
effectiveness compliance test data provided above indicate that there 
can be considerable variation in the average pedal force required to 
produce similar stopping distances. Nevertheless, the test results 
indicate that all the vehicles tested complied with the hot and 
recovery requirements of the standard. Accordingly, NHTSA believes that 
the testing problems suggested by AAMA will not develop into compliance 
issues unless the vehicle's brake performance is substantially degraded 
by heating.
    c. AAMA: The requested amendments would not reduce the stringency 
of the standard's requirements and would therefore have no adverse 
effect on safety. If anything, the requested amendments would increase 
the stringency of the standard. For example, AAMA members have 
conducted Standard No. 135 testing using the allowable pedal force of 
500 Newtons. This affords maximum flexibility for using a pedal force 
of up to 500 Newtons in the hot and recovery tests. Applying the full 
500 Newton pedal force during cold effectiveness tests would be 
practical, objective, and repeatable and would provide a well-defined 
pedal force constraint for the thermal tests. The one shortcoming of 
such a force is that it fails to assure the ``apples-to-apples'' 
comparison intended for the hot and recovery tests since it allows 
artificially inflated pedal forces to be used during the hot and 
recovery stops. The requested amendments would resolve this problem, 
however. Further, the petition does not seek any change to the relevant 
performance requirements of the standard, namely that hot brakes be 
capable of achieving at least 60 percent of cold deceleration 
capability and that recovered brakes be capable of achieving between 70 
percent and 150 percent of cold deceleration capability.
    NHTSA: The agency disagrees with AAMA on this point. NHTSA believes 
that the proposed procedure would reduce the stringency and severity of 
the hot and recovery performance tests. The

[[Page 9118]]

constant deceleration rate proposed by AAMA for the baseline tests (5.5 
m/s2) is lower than the current deceleration rate (6.43 m/
s2) the vehicle must achieve in order to meet the 70-meter 
cold effectiveness stopping distance performance requirement. The 
average minimum stopping distance for the cold effectiveness stopping 
tests shown above is about 50 meters. That results from an average 
deceleration rate of approximately 7.7 m/s2, or about 30 
percent higher than the average deceleration rate of AAMA's proposed 
baseline tests. Thus, AAMA's proposal to use a lower deceleration rate 
would result in the allowance of a longer stopping distance for the hot 
and recovery performance tests. Additionally, the agency has not used 
the allowable 500 N pedal force in the FMVSS No. 135 compliance tests 
conducted to date, so the allowable pedal forces for the hot and 
recovery performance tests conducted to date are not inflated.
    d. AAMA: The adoption of baseline stops at the beginning of the 
thermal sequence would avoid the effects of intervening tire and brake 
conditioning inherent in the current procedure. As currently written, 
high speed effectiveness, stops with the engine off, failed antilock, 
failed proportioning valve, hydraulic circuit failure, and parking 
brake tests, some under both gross and lightly-loaded vehicle 
conditions, are performed between the cold effectiveness test and the 
thermal tests. This sequence can confound the comparison between the 
hot, cold, and recovery tests. Adding the requested baseline stops at 
the outset of the thermal sequence would facilitate a more direct 
comparison of cold versus thermally affected braking capability.
    NHTSA: The agency agrees that baseline stopping runs at the 
beginning of the thermal sequence would avoid the effects of tire and 
brake conditioning that occur between the cold effectiveness testing 
and the thermal test sequence. NHTSA believes, however, that such 
effects are negligible when compared to the total brake and tire usage 
that occurs during conduct of the entire Standard No. 135 test series. 
In addition, the AAMA did not demonstrate any performance or safety 
benefits that would result from the requested change in test sequence. 
Accordingly, NHTSA sees no need to amend the testing procedures of 
Standard No. 135 to specify AAMA's proposed baseline testing for the 
purpose of eliminating the effects of tire wear or brake conditioning 
that might occur during testing.

C. Agency Determination

    The agency's declination to amend Standard No. 135 as suggested by 
AAMA includes the fact that the test procedures in Standard No. 135 and 
ECE R13-H are now harmonized. The AAMA proposals would move Standard 
No. 135 away from harmonization with its European counterpart. Absent 
sufficient safety reasons to change the existing test procedures in 
Standard No. 135, NHTSA finds no justification for adopting the 
manufacturers' request to move NHTSA's standards away from harmony with 
the European standards.
    The agency believes that the testing practicability problems 
asserted by AAMA in its petition for rulemaking will not result in 
vehicle noncompliance. As determined by NHTSA's compliance test results 
discussed above, the considerable range of pedal forces that result in 
similar stopping distances in the cold effectiveness testing has not 
resulted in any noncompliances with the hot and recovery requirements. 
Thus, NHTSA believes that it is more appropriate to compare hot and 
recovery brake performance to peak cold effectiveness performance than 
to compare non-peak cold brake performance against the hot and recovery 
performance. The agency also believes that the amendments to Standard 
No. 135 suggested by AAMA would reduce the stringency and severity of 
the hot and recovery performance tests specified in the standard, and 
thus would be inconsistent with motor vehicle safety.
    Finally, the proposed amendments would add complexity to the 
compliance test procedures in Standard No. 135 without demonstrated 
safety or testing benefits.
    For the reasons stated above, the agency terminates rulemaking 
initiated by the petition for rulemaking submitted by the AAMA.

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

    Issued on: February 18, 1999.
Ricardo Martinez,
Administrator.
[FR Doc. 99-4522 Filed 2-23-99; 8:45 am]
BILLING CODE 4910-59-P