Document ID: NHTSA-2009-0175-0006
Agency: nhtsa
Document Type: Rule
Title: Federal Motor Vehicle Safety Standards: Air Brake Systems
Posted Date: 2011-07-27T04:00Z

[Federal Register Volume 76, Number 144 (Wednesday, July 27, 2011)]
[Rules and Regulations]
[Pages 44829-44834]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-18929]

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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA-2009-0175]
RIN 2127-AK84

Federal Motor Vehicle Safety Standards; Air Brake Systems

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

ACTION: Final rule; response to petitions for reconsideration.

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SUMMARY: On July 27, 2009, NHTSA published a final rule that amended 
the Federal motor vehicle safety standard for air brake systems by 
requiring substantial improvements in stopping distance performance on 
new truck tractors. In response, the agency received eight petitions 
for reconsideration. The agency has already responded to most of the 
issues raised in the petitions. This document responds to the one 
outstanding issue raised in the petitions, stopping distance 
performance requirements at lower initial speeds. Based on testing 
results and our concern that the current requirements might not be 
practicable, NHTSA is slightly relaxing the stopping distance 
requirement for typical loaded tractors tested from an initial speed of 
20 mph by increasing the distance from 30 feet to 32 feet and for 
unloaded tractors tested from an initial speed of 20 mph by increasing 
the distance from 28 feet to 30 feet. We believe no other changes are 
necessary.

DATES: This final rule is effective August 1, 2011.
    Petitions for reconsideration must be received not later than 
September 12, 2011.

ADDRESSES: Petitions for reconsideration should refer to the docket 
number and must be submitted to: Administrator, National Highway 
Traffic Safety Administration, 1200 New Jersey Avenue, SE., Washington, 
DC 20590.

FOR FURTHER INFORMATION CONTACT: For technical issues, you may contact 
Jeffrey Woods, Office of Crash Avoidance Standards, by telephone at 
(202) 366-6206, and by fax at (202) 366-7002.
    For legal issues, you may contact David Jasinski, Office of the 
Chief Counsel, by telephone at (202) 366-2992, and by fax at (202) 366-
3820.
    You may send mail to both of these officials at the National 
Highway Traffic Safety Administration, 1200 New Jersey Avenue, SE., 
Washington, DC 20590.

SUPPLEMENTARY INFORMATION: 

Table of Contents

I. Background of the Stopping Distance Requirement
II. Petitions for Reconsideration
III. Testing Program
IV. Response to Petition
V. Technical Correction
VI. Effective Date
VII. Rulemaking Analyses and Notices
VIII. Regulatory Text

I. Background of the Stopping Distance Requirement

    On July 27, 2009, NHTSA published a final rule in the Federal 
Register amending Federal Motor Vehicle Safety Standard (FMVSS) No. 
121, Air Brake Systems, to require improved stopping distance 
performance for heavy truck tractors.\1\ This rule reduced the maximum 
allowable stopping distance, from 60 mph, from 355 feet to 250 feet for 
the vast majority of loaded heavy truck tractors. For a small minority 
of loaded very heavy tractors, the maximum allowable stopping distance 
was reduced from 355 feet to 310 feet. Having come to the conclusion 
that modifications needed for ``typical three-axle tractors,'' to meet 
the improved requirements were relatively straightforward, NHTSA 
provided two years lead time for those vehicles to comply with the new 
requirements. These typical three-axle tractors comprise approximately 
82 percent of the total fleet of heavy tractors. The agency concluded 
that other tractors, which are produced in far fewer numbers and may 
need additional work to ensure stability and control while braking, 
would need more lead time to meet the requirements. Due to extra time 
needed to design, test, and validate these vehicles, which included 
two-axle tractors and severe service tractors, the agency allowed four 
years lead time for

[[Page 44830]]

these tractors to meet the improved stopping distance requirements.
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    \1\ 74 FR 37122; Docket No. NHTSA-2009-0083-0001.
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    Requirements in FMVSS No. 121 provide that if the speed attainable 
by a vehicle in two miles is less than 60 mph, the speed at which the 
vehicle shall meet the specified stopping distances is four to eight 
mph less than the speed attainable in two miles. In the July 2009 final 
rule, the agency used an equation to derive the required stopping 
distances for vehicles with initial speeds of less than 60 mph.\2\
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    \2\ The complete derivation for this equation was included in 
the docket. See Docket No. NHTSA-2005-21462-0039, at 18-22.

St = (\1/2\ Vo tr) + ((\1/2\) 
Vo[sup2]/af)--((\1/24\) af 
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tr[sup2])

Where:

St = Total stopping distance in feet
Vo = Initial Speed in ft/sec
tr = Air pressure rise time in seconds
af = Steady-state deceleration in ft/sec[sup2]

    For the final rule, the agency selected an air pressure rise time 
of 0.45 seconds, which is equal to the brake actuation timing 
requirement in FMVSS No. 121. The steady-state deceleration was based 
on an theoretical deceleration curve in which vehicle deceleration 
would increase linearly during the rise time portion of the stopping 
event, followed by constant steady-state deceleration, followed by an 
instantaneous decrease in acceleration back to zero at the completion 
of the stop. Table II in FMVSS No. 121 sets forth the stopping distance 
requirements for speeds from 60 mph down to 20 mph (in increments of 5 
mph) for both typical and severe service tractors in the loaded 
conditions and all tractors in the unloaded condition derived using 
that formula.

II. Petitions for Reconsideration

    NHTSA received eight timely petitions for reconsideration in 
response to the final rule. Separate petitions were received from the 
Truck Manufacturers Association (TMA); the Heavy Duty Brake 
Manufacturers Council of the Heavy Duty Manufacturers Association 
(HDBMC); Bendix Spicer Foundation Brake LLC (Bendix), a joint venture 
between Bendix Commercial Vehicle Systems and Dana Corporation; and 
ArvinMeritor. The agency received four additional petitions supporting 
and incorporating the TMA petition by reference from Daimler Trucks 
North America (Daimler), Kenworth Truck Company (Kenworth), Peterbilt 
Motors Company (Peterbilt), and Navistar Truck Group (Navistar).
    The petitions focused on four main issues. The main issues included 
the stopping distance requirements for reduced speeds, the omission of 
four-axle tractors under 59,600 pounds gross vehicle weight rating 
(GVWR) from the listed requirements and the date at which the improved 
stopping distance requirements should apply to those tractors, the 
manner in which NHTSA characterized the typical three-axle tractor, and 
the fuel tank fill level testing specification. Additionally, the 
petitioners requested that NHTSA correct some typographical errors in 
the regulatory text.
    In a final rule published in the Federal Register on November 13, 
2009, the agency addressed all of the issues raised in the petition, 
except those related to stopping distance requirements at reduced 
speeds.\3\ We addressed the other issues first because the agency 
omitted lead time requirements for tractors with four or more axles and 
a GVWR of 59,600 pounds or less, which would have inadvertently 
required those vehicles to comply with the upgraded stopping distance 
requirements on November 24, 2009. The November 2009 final rule 
responded to issues raised in the petition with these amendments: (1) 
The agency accepted the recommendation of petitioners TMA, HDBMC, and 
Bendix and required compliance with the improved stopping distance 
requirements for tractors with four or more axles and a GVWR of 59,600 
pounds or less by August 1, 2013, thereby giving four years of lead 
time; (2) the agency revised the definition of a ``typical three-axle 
tractor'' in the regulatory text in response to concerns raised by TMA 
and ArvinMeritor to include three-axle tractors having a steer axle 
gross axle weight rating (GAWR) of 14,600 pounds or less and a combined 
drive axle GAWR of 45,000 pounds or less; (3) the agency removed the 
fuel tank loading specification from the test procedure in response to 
TMA's petition; (4) the agency made two typographical corrections 
identified by all petitioners.\4\
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    \3\ 74 FR 58562; Docket No. NHTSA-2009-0175-0001.
    \4\ The agency made further correcting amendments to correct an 
omission in the November 2009 final rule. See 75 FR 15620 (Mar. 30, 
2010); Docket No. 2009-0175-0004.
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    TMA, HDBMC, and Bendix each raised issues in their petitions 
regarding stopping distance requirements at reduced test speeds. TMA, 
HDBMC, and Bendix each stated that the new stopping distance 
requirements from speeds lower than 60 mph have not been validated 
through actual vehicle test data. In addition, the agency received a 
comment on the November 2009 final rule from Crystal Vangorder, which 
supported this assertion. TMA and Ms. Vangorder requested that the 
agency withdraw the reduced stopping distance requirements from speeds 
lower than 60 mph until test data has been obtained.
    Although HDBMC reviewed NHTSA's calculations and assumptions set 
forth in the preamble to the final rule and agreed with the technical 
approach taken, HDBMC nevertheless stated that the brake timing may be 
too fast for some vehicle configurations. HDBMC made reference to its 
own prior comments on the agency's reduced stopping distance rulemaking 
in which it provided tables showing how brake timing affects stopping 
distance.\5\ HDBMC noted that high braking torques can occur prior to 
load transfer, which may cause deep cycling of the antilock brake 
system (ABS) resulting in slightly longer stopping distance. Bendix 
also stated that differing opinions on axle response time and average 
deceleration left the results of the calculations open to speculation. 
HDBMC noted that limited initial testing data by its members showed 
that vehicle are close to meeting or are not meeting the stopping 
distance from 20 mph of 30 feet within a 10 percent margin.
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    \5\ See Docket No. NHTSA-2005-21462-0020.
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    TMA and HDBMC both stated that their members were conducting 
testing and would provide the agency with data to supplement any agency 
testing. However, no test data has been provided to the agency.

III. Testing Program

    In response to the petitions, NHTSA conducted testing to evaluate 
the stopping distance performance of a truck tractor from initial test 
speeds between 20 and 60 mph. The purpose of the testing was to acquire 
test data that, as stated in the petitions for reconsideration to the 
July 2009 final rule, had not been available to confirm that the new 
stopping distance requirements from speeds less than 60 mph could be 
achieved. The test program and results are described in the technical 
report, ``Experimental Measurement of the Stopping Performance of a 
Tractor-Semitrailer from Multiple Speeds.'' \6\
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    \6\ DOT HS 811 488, available at http://www.nhtsa.gov/DOT/NHTSA/NVS/Vehicle Research & Test Center (VRTC)/ca/811488.pdf, Docket No. 
NHTSA-2009-0175-0005.
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    The test plan was to evaluate a tractor that, when tested while 
traveling at a speed of 60 mph, met the reduced tractor stopping 
distance requirement of 250 feet for vehicles loaded to GWVR without 
any margin. That same tractor was then tested at lower initial speeds 
to compare actual test results with the new requirements in Table II of 
FMVSS

[[Page 44831]]

No. 121. The test was also conducted in a lightly loaded vehicle weight 
condition with no trailer attached.
    The agency used a 1991 Volvo 6x4 tractor with a 190-inch wheelbase, 
equipped with a hybrid disc brake configuration. The vehicle was used 
in the agency's research to support the reduced stopping distance 
rulemaking, and was chosen because it was expected to have close to a 
250-foot stopping distance when tested from 60 mph in the loaded 
condition. During actual testing, the vehicle was found to have a 
minimum stopping distance of 249 feet when loaded to GVWR (i.e., the 
shortest stop in a series of six stops).\7\ However, the vehicle had 
not been operated for several years and when the vehicle was 
recommissioned for this test program, the agency found it necessary to 
adjust the amount of the ballast load of the vehicle by lowering it to 
a modified GVWR in order to achieve consistent stopping distance of 250 
feet from 60 mph.\8\ This modified GVWR was used for the rest of the 
testing program.
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    \7\ Repairs were necessary to this vehicle in order to meet the 
0.45 second brake application timing requirement.
    \8\ The tractor's GVWR was 50,000 pounds. The load necessary to 
meet the 250-foot stopping requirement with the control trailer 
attached was 42,840 pounds.
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    The agency considered using a newer vehicle and adding ballast to 
increase the stopping distance of the vehicle to 250 feet. However, the 
agency decided not to follow this approach because it could have 
resulted in unusually high brake temperatures and brake fade effects or 
changes in the brake lining friction characteristics. The agency 
believed it would be better to remove weight from a worse-performing 
tractor rather than adding weight to a better-performing tractor.
    A series of six stops was then conducted for the loaded tractor at 
initial speeds ranging from 60 mph down to 20 mph in five-mph 
increments. The average of each six-stop series was compared to the new 
requirements in column (3) of Table II of FMVSS No. 121. The results 
indicated that from initial speeds below 60 mph, the vehicle could 
achieve slightly better stopping distances than those in Table II, 
except at the lowest test speed of 20 mph. From an initial speed of 20 
mph, the tractor loaded to the modified GVWR achieved an average 
stopping distance of 31.2 feet, compared to the FMVSS No. 121 stopping 
distance requirement of 30 feet.
    The test series was then repeated in the unloaded (bobtail) 
condition. For this test series, the agency was unable to devise a 
practical way of adjusting the tractor's braking performance to provide 
a zero percent margin of compliance at 60 mph. These results were 
compared to the new requirements in column (6) of Table II of FMVSS No. 
121. The results indicated that the tractor performed with a 20 to 25 
percent margin of compliance at initial test speeds between 30 and 60 
mph. However, at the two lowest test speeds, the margin of compliance 
was less--16 percent at 25 mph and eight percent at 20 mph.
    When compared to the theoretical deceleration curve discussed in 
the July 2009 final rule, there were differences. The theoretical 
deceleration curve has a linear increase in deceleration during the 
rise time, followed by a constant steady-state deceleration, and then 
an instantaneous decrease in deceleration to zero at the completion of 
the stop. In comparison, the test data generally followed this shape 
with some differences. There was substantial signal noise in the 
measured deceleration, which has been observed in other heavy vehicle 
braking tests. Because of this signal noise, the data analyst had to 
use judgment in determining the completion of the rise time. The 
steady-state deceleration also was not constant. It appeared to be 
higher toward the end of the stop as the vehicle speed decreased during 
the stop. At the end of the stop, the test data indicated a steep ramp 
down in deceleration to zero, but it was not the instantaneous drop 
shown in the theoretical curve.
    For the new stopping distance requirements, the rise time used in 
the stopping distance equation was 0.45 seconds, and the preamble of 
the July 2009 final rule provided the required steady-state 
decelerations for the various initial test speeds that would be 
required to achieve the new stopping distances. For example, for a 
typical tractor from an initial speed of 60 mph with a rise time of 
0.45 seconds and a stopping distance of 250 feet, the required steady-
state deceleration in the equation was 16.80 ft/sec\2\.
    When compared to the actual test data in the loaded condition from 
60 mph, the average stopping distance was 251 feet, the rise time was 
0.40 seconds, and the steady-state deceleration was 17.3 ft/sec\2\. 
Although the rise time was slightly faster and the stopping distance 
very slightly worse, the measured steady-state deceleration was higher 
than predicted. Deriving the steady-state deceleration from the 
equation using the observed stopping distance and rise time would 
result in a predicted steady-state deceleration of 16.6 ft/sec\2\, 
which is four percent lower than what was observed. Although the 
difference is small, the divergence became greater at lower initial 
test speeds. At the lowest test speed of 20 mph, the measured steady-
state deceleration of the vehicle was 20 ft/sec\2\, which is 2.9 ft/
sec\2\ or 17 percent higher than the predicted value of 17.1 ft/sec\2\ 
from the equation. Similar differences, though not as great were 
observed from tests in the unloaded condition.
    The test results also revealed that the agency was correct in 
assuming that higher steady-state deceleration would be achieved at 
lower initial test speeds due to increasing tire adhesion as the 
vehicle speed decreases when considering speeds between 60 and 35 mph. 
However, for the loaded tractor tests conducted at the lowest initial 
speeds, the measured steady-state deceleration actually decreased from 
21.4 ft/sec\2\ at an initial test speed of 25 mph to 20.0 ft/sec\2\ at 
an initial test speed of 20 mph. For the unloaded tests, the steady-
state deceleration decreased from 24.7 ft/sec\2\ at an initial test 
speed of 35 mph to 21.7 ft/sec\2\ at an initial test speed of 20 mph. 
The reduced steady-state deceleration at these lower test speeds 
appears to be an influential factor in the loaded tractor's not meeting 
the new 20 mph stopping distance of 30 feet and in the reduced margin 
of compliance for the unloaded tractor tests at the lowest test speeds 
of 25 and 20 mph.
    The testing also provided data on the rise times that were achieved 
for the two loading conditions at the various test speeds, although 
they had to be determined based on engineering judgment due to the 
signal noise. For the tests in the loaded condition, the average rise 
time based on the six stops at each test speed ranged between 0.39 and 
0.56 seconds. The longest average rise times of 0.50 and 0.56 seconds 
occurred at the initial test speeds of 30 and 25 mph, respectively. 
From an initial test speed of 20 mph, the average rise time decreased 
to 0.42 seconds. Otherwise, there was no clear trend for the rise times 
when compared to initial test speed. Within each set of six stops for 
each test speed, some showed considerable variability between the six 
stops and some did not, with standard deviations ranging between 0.11 
seconds from an initial speed of 30 mph (minimum 0.37 seconds, maximum 
0.60 seconds) to 0.02 seconds from an initial speed of 40 mph (minimum 
0.36 seconds, maximum 0.41 seconds).
    The rise times for the unloaded tractor tests were substantially 
lower than those for the loaded tests. There was also much less 
variability in the unloaded tests compared to the loaded tests, with

[[Page 44832]]

average rise times for each six-stop series ranging between 0.27 and 
0.32 seconds. The standard deviation for each six-stop series ranged 
between 0.01 seconds and 0.03 seconds.
    The agency did not specifically evaluate ABS cycling during stops. 
However, based on a review of the wheel speed data, we are able to make 
some observations. The ABS had the most activity when the tractor was 
tested in the unloaded condition, in which there were continuous brake 
pressure modulations for the drive axles throughout all of the stops 
from all initial test speeds. The intermediate drive axle was equipped 
with ABS wheel speed sensors and the brake pressures for both drive 
axles were modulated based upon the wheel slip occurring on this drive 
axle. For tests in the loaded condition, the wheel speed data for the 
drive axles did not show any indications of substantial wheel slip on 
the intermediate drive axle, although brake pressure modulation was 
observed in about half of the stops, mostly at the beginning of the 
stop, indicating that ABS did activate in those stops. ABS activity on 
the steer axle was mixed. Some tests in the loaded condition showed 
steer axle brake pressure modulations of up to 30 psi followed by 
stair-stepping pressure increases. As with the drive axle, there was 
much more ABS activity on the steer axle during the unloaded stops. 
However, none of the ABS activity on the steer or drive axles was 
considered to be deep cycling in which the pressure is modulated to 
near zero or held at low pressures for a substantial amount to time in 
response to rapid wheel lockup, and there were no observed lapses in 
deceleration resulting from ABS activity.

IV. Response to Petition

    Because of the lack of test data on the stopping distance for 
tractors from reduced stopping distance, the agency conducted the 
testing program to determine the accuracy of the equation from which 
the agency derived the stopping distances and to determine whether a 
test tractor could readily achieve the new reduced stopping distances 
from each of the initial test speeds. Because the agency has conducted 
testing that verified the stopping distance requirements at reduced 
test speeds, the agency has decided not to set aside or withdraw the 
stopping distance requirements at reduced initial test speeds, as 
requested by TMA and supported by Ms. Vangorder.
    Regarding the validity of the stopping distance equation in the 
final rule that was used to derive the stopping distances from reduced 
speeds, the agency concludes that the theoretical deceleration profile 
that formed the basis of the equation had some inaccuracies.\9\ 
Although the testing demonstrated some slight inaccuracies in the 
equation, we have decided not to pursue refinements to the equation at 
this time to improve its accuracy in order to address the petitions for 
reconsideration. The results lead us to believe that further testing 
likely would not suggest a need for any significant changes to other 
stopping distance requirements nor would it lead to improvements in the 
robustness of the equation.
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    \9\ We believed that including the stopping distance equation in 
preamble to the final rule was useful to provide the agency's view 
on how tractors are anticipated to meet the stopping distance 
requirements at reduced speeds.
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    Regarding HDBMC's comments that the rise times used in the final 
rule would make very fast brake timings necessary and that could result 
in high braking torques occurring prior to load transfer and deep 
cycling of the ABS, and as a result those timings would contribute to 
longer stopping distances, we presume that HDMBC was referring 
primarily to the tractor's steer axle that experiences the greatest 
increase in load transfer during a maximum effort stop. In response to 
this concern, we note three observations from the agency's testing. 
First, the fastest rise times observed in the testing were in the 
unloaded condition and were approximately 0.30 seconds, which closely 
matched the average brake application timing of 0.31 seconds that was 
measured on the steer axle. Second, the brake application timing was 
not particularly fast on the drive axles (0.41 and 0.42 seconds for the 
rear and intermediate drive axles respectively), and the rise times for 
the tractors tested in the loaded condition were similar to the drive 
axle application timing (average of 0.43 seconds). Third, deep cycling 
of the ABS system was not observed during any stops in the unloaded and 
loaded conditions. The test tractor was able to meet nearly all of the 
stopping distance requirements without particularly fast brake 
application timing. Further, HDBMC never provided its own test data in 
support of its assertion that fast brake timings would be required to 
meet the stopping distance requirements at lower initial test speeds.
    Based on the foregoing, the agency has decided to increase the 
stopping distances set forth in Table II of FMVSS No. 121 for typical 
tractors in the loaded condition (column (3)) and for unloaded tractors 
(column (6)) from an initial speed of 20 mph. For typical tractors in 
the loaded condition, the agency is increasing the stopping distance 
from an initial speed of 20 mph from 30 feet to 32 feet. The basis for 
this change is that the agency's testing program showed decreased 
steady-state deceleration performance at this initial test speed 
compared to what was predicted. The agency based the 30-foot stopping 
distance on the assumption that lower initial test speeds would always 
have a higher steady-state deceleration when compared to higher initial 
test speeds. The tractor tests showed that this was the case between 
initial test speeds of 60 and 35 mph. However, variations occurred 
below 25 mph. We believe that braking tests with initial speeds below 
35 mph are of such short duration that there is insufficient time to 
attain and maintain the level of steady-state deceleration performance 
that is seen from higher initial braking speeds.
    The agency is also increasing the stopping distance for tractors in 
the unloaded condition from an initial speed of 20 mph from 28 feet to 
30 feet. In the agency's testing, the test tractor exceeded the new 
stopping distances in the unloaded condition from initial test speeds 
between 60 mph and 30 mph by a margin of greater than 20 percent. At 25 
mph, the compliance margin narrowed to 16 percent, and at 20 mph, the 
compliance margin further narrowed to eight percent. Increasing the 
unloaded stopping distance from 28 feet to 30 feet would improve the 
margin of compliance to 14 percent. The eight percent margin of 
compliance stands out when considering that a tractor that would not 
have as good of braking performance as the tractor tested, such that it 
would have lower margins of compliance at higher initial test speeds. 
As we stated above, we were not able to test an unloaded tractor with a 
zero margin of compliance from an initial test speed of 60 mph. We are 
making this change in anticipation that some atypical tractors with 
lower margins of compliance in the unloaded condition would have 
difficulty achieving the 28 foot stopping distance.
    The agency notes that these changes are being made based on the 
testing of a tractor that was adjusted to just meet the stopping 
distance requirements for the stops from 60 mph in the loaded 
condition. We anticipate that tractors with improved braking 
performance will be designed to have a greater-than-zero margin of 
compliance to the new stopping distance requirements so that minor 
variations in the vehicle manufacturing process and brake components 
can be tolerated. Thus, we

[[Page 44833]]

expect that the stopping distance performance of vehicles at all 
initial test speeds would be slightly better as well. The agency has 
received no additional test data after the petitions for 
reconsideration were filed. We are therefore amending the stopping 
distances for reduced initial speeds based solely upon the agency's own 
test data.
    We also wish to clarify that tractors, trucks, and buses must only 
meet the stopping distance requirements at the initial test speed 
corresponding to the highest speed attainable by the vehicle. As stated 
in S5.3.1.1 of FMVSS No. 121, vehicle stops are generally conducted 
from 60 mph in both the loaded and unloaded conditions. However, if the 
speed attainable by a vehicle in two miles is less than 60 mph, the 
vehicle is required to stop from a speed in Table II that is four to 
eight mph less than the speed attainable in two miles. Thus, FMVSS No. 
121 does not require that stops be conducted from all initial test 
speeds listed in Table II; rather, stopping distance tests are 
conducted from either 60 mph or from the speed that is four to eight 
mph less than the highest speed attainable within two miles.

V. Technical Correction

    In the notes portion of Table II of FMVSS No. 121, the label for 
column (6) is ``Unloaded Tractors (Bobtail),'' which is the stopping 
distance requirements for unloaded tractors using the service brakes, 
whereas the label for column (8) is ``Unloaded Tractors,'' which is the 
stopping distance requirements for unloaded tractors using the 
emergency brake. The vehicle loading conditions tested in columns (6) 
and (8) are identical. The term ``Bobtail'' is included as a 
parenthetical to the label for column (6) to make clear that the 
stopping distance requirements in that column are to be met without a 
trailer attached. So there is no confusion that the loading condition 
for column (8) is identical to the loading condition for column (6), we 
are adding the term ``Bobtail'' in parenthesis in the label for column 
(8).

VI. Effective Date

    Section 30111(d) of title 49, United States Code, provides that a 
Federal motor vehicle safety standard may not become effective before 
the 180th day after the standard is prescribed or later than one year 
after it is prescribed except when a different effective date is, for 
good cause shown, in the public interest. This rule makes amendments to 
regulatory provisions that are subject to phase-in that were set forth 
in the July 2009 final rule. These amendments would not impose new 
requirements; rather, these amendments simply adjust the required 
maximum stopping distances at very low speeds by slightly relaxing them 
to be consistent with what the agency intended in the April 2007 final 
rule. Therefore, good cause exists for these amendments to be made 
effective in the timeframe already in place concerning the effective 
dates of implementation of the reduced stopping distance requirements 
in FMVSS No. 121.

VII. Rulemaking Analyses and Notices

A. Executive Order 12866, Executive Order 13563, and DOT Regulatory 
Policies and Procedures

    The agency has considered the impact of this rulemaking action 
under Executive Orders 12866 and 13563 and the DOT's regulatory 
policies and procedures. This action was not reviewed by the Office of 
Management and Budget under Executive Order 12866. The agency has 
considered the impact of this action under the Department of 
Transportation's regulatory policies and procedures (44 FR 11034; 
February 26, 1979), and has determined that it is not ``significant'' 
under them.
    This action completes the agency's response to petitions for 
reconsideration regarding the July 2009 final rule amending FMVSS No. 
121. This final rule revises the stopping distance table for vehicles 
from very low speeds to reflect agency's intent in the July 2009 final 
rule regarding braking performance level from very low test speeds. 
Today's action will not cause any additional expenses for vehicle 
manufacturers. This action will not have any significant safety 
impacts.

B. Privacy Act

    Anyone is able to search the electronic form of all documents 
received into any of our dockets by the name of the individual 
submitting the document (or signing the document, if submitted on 
behalf of an association, business, labor union, etc.). You may review 
DOT's complete Privacy Act Statement in the Federal Register published 
on April 11, 2000 (Volume 65, Number 70; Pages 19477-78) or you may 
visit http://docketsinfo.dot.gov/.

C. Other Rulemaking Analyses and Notices

    In the July 2009 final rule, the agency discussed relevant 
requirements related to the Regulatory Flexibility Act, the National 
Environmental Policy Act, Executive Order 13132 (Federalism), the 
Unfunded Mandates Reform Act, Civil Justice Reform, the National 
Technology Transfer and Advancement Act, the Paperwork Reduction Act, 
and Executive Order 13045 (Protection of Children from Environmental 
Health and Safety Risks). As today's rule merely makes minor changes in 
the stopping distance at lower speeds to reflect agency's intent in the 
July 2009 final rule regarding braking performance level from very low 
test speeds, it will not have any effect on the agency's analyses in 
those areas.

VIII. Regulatory Text

List of Subjects in 49 CFR Parts 571

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

    In consideration of the foregoing, NHTSA amends 49 CFR part 571 as 
follows:

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

0
1. The authority citation for part 571 of Title 49 continues to read as 
follows:

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

0
2. In Sec.  571.121, revise Table II to read as follows:

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

* * * * *

                                                           Table II--Stopping Distance in Feet
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                  Service brake                                      Emergency brake
         Vehicle speed in miles per hour         -------------------------------------------------------------------------------------------------------
                                                    PFC 0.9      PFC 0.9      PFC 0.9      PFC 0.9      PFC 0.9      PFC 0.9      PFC 0.9      PFC 0.9
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          (1)          (2)          (3)          (4)          (5)          (6)          (7)          (8)
                                                 -------------------------------------------------------------------------------------------------------
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(1) Loaded and Unloaded Buses.
(2) Loaded Single-Unit Trucks.
(3) Loaded Tractors with Two Axles; or with Three Axles and a GVWR of 70,000 lbs. or less; or with Four or More Axles and a GVWR of 85,000 lbs. or less.
  Tested with an Unbraked Control Trailer.
(4) Loaded Tractors with Three Axles and a GVWR greater than 70,000 lbs.; or with Four or More Axles and a GVWR greater than 85,000 lbs. Tested with an
  Unbraked Control Trailer.
(5) Unloaded Single-Unit Trucks.
(6) Unloaded Tractors (Bobtail).
(7) All Vehicles except Tractors, Loaded and Unloaded.
(8) Unloaded Tractors (Bobtail).

* * * * *

    Issued on: July 21, 2011.
Ronald L. Medford,
Deputy Administrator.
[FR Doc. 2011-18929 Filed 7-26-11; 8:45 am]
BILLING CODE 4910-59-P