[Federal Register Volume 72, Number 224 (Wednesday, November 21, 2007)]
[Proposed Rules]
[Pages 65509-65532]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 07-5758]
[[Page 65509]]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
[Docket No. NHTSA-2007-0014]
RIN 2127-AK09
Federal Motor Vehicle Safety Standards; Seating Systems, Occupant
Crash Protection, Seat Belt Assembly Anchorages, School Bus Passenger
Seating and Crash Protection
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation (DOT).
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: NHTSA issued a report in 2002 on the results of a
comprehensive school bus research program examining ways of further
improving school bus safety. Based on that research, we are now
proposing several upgrades to the school bus passenger crash protection
requirements.
For new school buses of 4,536 kilograms (10,000 pounds) or less
gross vehicle weight rating (GVWR), we propose to require lap/shoulder
belts in lieu of the lap belts that are currently specified. For school
buses with gross vehicle weight ratings (GVWR) greater than 4,536
kilograms (kg) (10,000 pounds), this NPRM provides guidance to State
and local jurisdictions on the subject of installing seat belts. Each
State or local jurisdiction would continue to decide whether to install
belts on these large school buses. Where State or local decisions are
made to install lap or lap/shoulder belts on large school buses, this
NPRM proposes performance requirements for those voluntarily-installed
seat belts on large school buses manufactured after the proposed
effective date.
Other changes to school bus safety requirements are also proposed,
including raising the height of seat backs from 20 inches to 24 inches
on all new school buses.
DATES: Comments must be received on or before January 22, 2008.
ADDRESSES: You may submit comments to the docket number identified in
the heading of this document by any of the following methods:
Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the online instructions for submitting
comments.
Mail: Docket Management Facility, M-30, U.S. Department of
Transportation, West Building, Ground Floor, Rm. W12-140, 1200 New
Jersey Avenue, SE., Washington, DC 20590.
Hand Delivery or Courier: West Building Ground Floor, Room
W12-140, 1200 New Jersey Avenue, SE., between 9 a.m. and 5 p.m. Eastern
Time, Monday through Friday, except Federal holidays.
Fax: (202) 493-2251.
Regardless of how you submit your comments, you should mention the
docket number of this document.
You may call the Docket at 202-366-9324.
Instructions: For detailed instructions on submitting comments and
additional information on the rulemaking process, see the Public
Participation heading of the Supplementary information section of this
document. Note that all comments received will be posted without change
to http://www.regulations.gov, including any personal information
provided.
Privacy Act: Please see the Privacy Act heading under Rulemaking
Analyses and Notices.
FOR FURTHER INFORMATION CONTACT: For non-legal issues, Mr. Charles
Hott, Office of Vehicle Safety Standards (telephone: 202-366-0247)
(fax: 202-366-4921). Mr. Hott's mailing address is National Highway
Traffic Safety Administration, NVS-113, 1200 New Jersey Avenue, SE.,
Washington, DC 20590.
For legal issues, Ms. Dorothy Nakama, Office of the Chief Counsel
(telephone: 202-366-2992) (fax: 202-366-3820). Ms. Nakama's mailing
address is National Highway Traffic Safety Administration, NCC-112,
1200 New Jersey Avenue, SE., Washington, DC 20590.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Introduction
II. Background
III. The Issue of Seat Belts on Large School Buses
IV. Studies
V. Federal Guidance on Belts on Large Buses
a. NHTSA School Bus Research Results
b. Agency Recommended Best Practices
c. Guidance on Lap Belts on Large School Buses
VI. Proposed Upgrades to Occupant Crash Protection
a. Improving the Compartmentalized School Bus Interior of Both
Small and Large School Buses
b. Additional Occupant Protection Requirements for Small School
Buses (School Buses With a GVWR of 4,536 kg (10,000 lb) or Less)
c. Additional Occupant Protection Requirements for Large School
Buses With Voluntarily-Installed Lap/Shoulder Seat Belts
d. Additional Requirements for Large School Buses with
Voluntarily-Installed Lap Belts
VII. Quasi-Static Test for Lap/Shoulder Belts on Small and Large
School Buses
a. Stage 1: Torso Belt Anchorage Displacement
b. Stage 2: Energy Absorption Capability of the Seat Back
c. Request for Comments
VIII. Lead Time
IX. Rulemaking Analyses and Notices
X. Public Participation
Appendix A to the Preamble--Proposed Amendments to Federal Motor
Vehicle Safety Standards
I. Introduction
This document proposes to upgrade the school bus occupant
protection requirements of the Federal motor vehicle safety standards,
primarily by amendments to Federal Motor Vehicle Safety Standard No.
(FMVSS) No. 222, ``School bus passenger seating and crash protection''
(49 CFR 571.222), and by amendments to FMVSS Nos. 207, 208, and 210. It
also provides guidance to state and local jurisdictions on the subject
of installing seat belts on large school buses (school buses with a
GVWR greater than 4,536 kilograms (kg) (10,000 pounds (lb)) and asks
for comments on the agency's consideration of ``best practices''
concerning the belts on the large buses.\1\
---------------------------------------------------------------------------
\1\ ``School bus'' is defined in 49 CFR Sec. 571.3 as a bus
that is sold, or introduced in interstate commerce, for purposes
that include carrying students to and from school or related events,
but does not include a bus designed and sold for operation as a
common carrier in urban transportation. A ``bus'' is a motor
vehicle, except a trailer, designed for carrying more than 10
persons. In this NPRM, when we refer to ``large'' school buses, we
refer to those school buses with GVWRs of more than 4,536 kg (10,000
lb). These large school buses may transport as many as 90 students.
``Small'' school buses are school buses with a GVWR of 4,536 kg
(10,000 lb) or less. Generally, these small school buses seat 15
persons or fewer, or have one or two wheelchair seating positions.
---------------------------------------------------------------------------
This NPRM's most significant proposed changes to FMVSS No. 222
involve:
Increasing the minimum seat back height requirement from
20 inches from the seat's seating reference point (SgRP) to 24 inches
for all school buses;
Requiring small school buses to have a lap/shoulder belt
at each passenger seating position (the buses are currently required to
have lap belts);
Incorporating test procedures into the standard to test
lap/shoulder belts in small school buses and voluntarily-installed lap/
shoulder belts in large school buses to ensure both the strength of the
anchorages and the compatibility of the seat with compartmentalization;
and,
Requiring all school buses with seat bottom cushions that
are designed to flip-up, typically for easy cleaning, to have a self-
latching mechanism.
[[Page 65510]]
The proposed guidance to state and local jurisdictions on best
practices of installing seat belts on large school buses acknowledges
that, in terms of the optimum passenger crash protection that can be
afforded an individual passenger on a large school bus, a lap/shoulder
belt system, together with compartmentalization, would afford that
optimum protection. Thus, we encourage providers to consider lap/
shoulder belts on large school buses. However, installing current lap/
shoulder belts on large school buses would reduce the passenger
carrying capacity of large buses. If children were diverted to other
means of transport to school, such as transport by smaller, private
vehicles, walking, or biking, the belts on the buses could result in an
overall disbenefit to pupil transportation safety due to the children
displaced from the large school buses having to find less safe modes of
transportation to get to or from school or related events. Thus, we are
not proposing to require lap/shoulder belts on large school buses, and
we recommend providers to ascertain whether installing lap/shoulder
belts would reduce the number of children that are transported to
school on large school buses.
II. Background
The Motor Vehicle and Schoolbus Safety Amendments of 1974 directed
NHTSA to issue motor vehicle safety standards applicable to school
buses and school bus equipment. In response to this legislation, NHTSA
revised several of its safety standards to improve existing
requirements for school buses, extended ones for other vehicle classes
to those buses, and issued new safety standards exclusively for school
buses. FMVSS No. 222, one of a set of new standards for school buses,
improves protection to school bus passengers during crashes and sudden
driving maneuvers.
Effective since 1977, FMVSS No. 222 contains occupant protection
requirements for school bus seating positions and restraining barriers.
Its requirements for school buses with GVWR's of 4,536 kg (10,000 lb)
or less differ from those set for school buses with GVWR's greater than
4,536 kg (10,000 lb), because the ``crash pulse'' or deceleration
experienced by the small school buses is more severe than that of the
large buses in similar collisions. For the small school buses, the
standard includes requirements that all seating positions must be
equipped with properly installed lap or lap/shoulder seat belt
assemblies and anchorages for passengers.\2\ NHTSA decided that seat
belts were necessary on small school buses to provide adequate crash
protection for the occupants. For the large school buses, FMVSS No. 222
relies on requirements for ``compartmentalization'' to provide
passenger crash protection. Investigations of school bus crashes prior
to issuance of FMVSS No. 222 found the school bus seat was a
significant factor in causing injury. NHTSA found that the seat failed
the passengers in three principal respects: by being too weak, too low,
and too hostile (39 FR 27584; July 30, 1974). In response to this
finding, NHTSA developed a set of requirements which comprise the
``compartmentalization'' approach.
---------------------------------------------------------------------------
\2\ Lap/shoulder belts and appropriate anchorages for the driver
and front passenger (if provided) seating position, lap belts and
appropriate anchorages for all other passenger seating positions.
---------------------------------------------------------------------------
Compartmentalization ensures that passengers are cushioned and
contained by the seats in the event of a school bus crash by requiring
school bus seats to be positioned in a manner that provides a compact,
protected area surrounding each seat. If a seat is not
compartmentalized by a seat back in front of it, compartmentalization
must be provided by a padded and protective restraining barrier. The
seats and restraining barriers must be strong enough to maintain their
integrity in a crash yet flexible enough to be capable of deflecting in
a manner which absorbs the energy of the occupant. They must meet
specified height requirements and be constructed, by use of substantial
padding or other means, so that they provide protection when they are
impacted by the head and legs of a passenger. Compartmentalization
minimizes the hostility of the crash environment and limits the range
of movement of an occupant. The compartmentalization approach ensures
that high levels of crash protection are provided to each passenger
independent of any action on the part of the occupant.
III. The Issue of Seat Belts on Large School Buses
NHTSA has considered the question of whether seat belts should be
required on large school buses from the inception of
compartmentalization and the school bus safety standards. NHTSA has
been repeatedly asked to require belts on buses, and has repeatedly
concluded that compartmentalization provides a high level of safety
protection that obviates the safety need for a Federal requirement
necessitating the installation of seat belts. Further, the agency has
been acutely aware that a decision on requiring seat belts in large
school buses cannot ignore the implications of such a requirement on
pupil transportation costs. The agency has been attentive to the fact
that, as a result of requiring belts on large school buses, school bus
purchasers would have to buy belt-equipped vehicles regardless of
whether seat belts would be appropriate for their needs. NHTSA has
concluded that those costs should not be imposed on all purchasers of
school buses when large school buses are currently very safe. In the
area of school transportation especially, where a number of needs are
competing for limited funds, persons responsible for school
transportation might want to consider other alternative investments to
improve their pupil transportation programs which can be more effective
at reducing fatalities and injuries than seat belts on large school
buses, such as by acquiring additional new school buses to add to their
fleet, or implementing improved pupil pedestrian and driver education
programs. Since each of these efforts competes for limited funds, the
agency has maintained that those administrators should decide how their
funds should be allocated.
IV. Studies
Nonetheless, throughout the past 30 years that compartmentalization
and the school bus safety standards have been in effect, the agency has
openly and continuously considered the merits of a seat belt
requirement for large school buses.\3\ The issue has been closely
analyzed by other parties as well, such as the National Transportation
Safety Board, and the National Academy of Sciences. Various reports
have been issued, the most significant of which are described below.
---------------------------------------------------------------------------
\3\ Through the years, NHTSA has been petitioned about seat
belts on large school buses. (See, e.g., denials of petitions to
require seat belt anchorages, 41 FR 28506 (July 12, 1976), 48 FR
47032 (October 17, 1983); response to petition for rulemaking to
prohibit the installation of lap belts on large school buses, 71 FR
40057 (July 14, 2006).) In a letter dated February 16, 2007, the
National Association of Pupil Transportation (NAPT) petitioned the
agency ``to initiate rulemaking on occupant protection in school
buses.'' NAPT said that it did not support the installation of lap
belts in large school buses, nor the installation of lap/shoulder
belts. NAPT stated it ``will only support changes to
compartmentalization when we are sure that those changes will not
compromise student safety in any way.'' NAPT requested that the
agency review FMVSS No. 222, ``with the goal of establishing a
safety system that will definitively enhance the current passenger
crash protection for all children that ride a school bus.'' NAPT
also advocated a public education program emphasizing the importance
of safe school bus transportation.
---------------------------------------------------------------------------
[[Page 65511]]
Studies
National Transportation Safety Board, 1987
In 1987, the National Transportation Safety Board (NTSB) reported
on a study of forty-three post-standard school bus crashes investigated
by the Safety Board. NTSB concluded that most fatalities and injuries
in school bus crashes occurred because the occupant seating positions
were directly in line with the crash forces, and that seat belts would
not have prevented those injuries and fatalities. (NTSB/SS-87/01,
Safety Study, Crashworthiness of Large Post-standard School Buses,
March 1987, National Transportation Safety Board.)
National Academy of Sciences, 1989
A 1989 National Academy of Sciences (NAS) study concluded that the
overall potential benefits of requiring seat belts on large school
buses were insufficient to justify a Federal mandate for installation.
The NAS also stated that funds used to purchase and maintain seat belts
might be better spent on other school bus safety programs with the
potential to save more lives and reduce more injuries. (Special Report
222, Improving School Bus Safety, National Academy of Sciences,
Transportation Research Board, Washington, DC, 1989.)
National Transportation Safety Board, 1999
In 1999, NTSB reported on six school bus crashes it investigated in
which passenger fatalities or serious injuries occurred away from the
area of vehicle impact. NTSB found compartmentalization to be an
effective means of protecting passengers in school bus crashes.
However, because many of those passengers injured in the six crashes
were believed to have been thrown from their compartments, NTSB
believed other means of occupant protection should be examined. (NTSB/
SIR-99/04, Highway Safety Report, Bus Crashworthiness Issues, September
1999, National Transportation Safety Board.)
National Academy of Science, 2002
In 2002, NAS published a study that analyzed the safety of various
transportation modes used by school children to get to and from school
and school-related activities. The report concluded that each year
there are approximately 815 school transportation fatal injuries per
year. Two percent were school bus-related, compared to 22 percent due
to walking/bicycling, and 75 percent from passenger car crashes,
especially those with teen drivers. The report stated that changes in
any one characteristic of school travel can lead to dramatic changes in
the overall risk to the student population. Thus, NAS concluded, it is
important for school transportation decisions to take into account all
potential aspects of changes to requirements to school transportation.
(Special Report 269, ``The Relative Risks of School Travel: A National
Perspective and Guidance for Local Community Risk Assessment,''
Transportation Research Board of the National Academies, 2002.)
National Highway Traffic Safety Administration, 2002
In 2002, NHTSA issued a Congressional Report that detailed occupant
safety on school buses and analyzed options for improving occupant
safety. NHTSA concluded that compartmentalization effectively lowered
injury measures by distributing crash forces with the padded seating
surface. Lap belts showed little to no benefit in reducing serious/
fatal injuries. The agency determined that properly used combination
lap and shoulder belts have the potential to be effective in reducing
fatalities and injuries for not only frontal collisions, but also
rollover crashes where belt systems are particularly effective in
reducing ejection. However, the addition of lap/shoulder belts on buses
would increase capital costs and reduce seating capacity on the buses.
(``Report to Congress, School Bus Safety: Crashworthiness Research,
April 2002,'' http://www-nrd.nhtsa.dot.gov/departments/nrd-11/SchoolBus/SBReportFINAL.pdf.)
V. Federal Guidance on Belts on Large Buses
This document provides guidance to state and local jurisdictions on
the subject of installing seat belts on large school buses and asks for
comments on the agency's consideration of ``best practices'' concerning
the belts on the large buses.
This guidance is provided in response to the information that the
agency received at its July 11, 2007 public meeting in Washington, DC
on seat belts on school buses (notice of public meeting, 72 FR 30739,
June 4, 2007, Docket 28103).\4\ In this meeting, NHTSA brought together
a roundtable of State and local government policymakers, school bus and
seat manufacturers, pupil transportation associations, and consumer
groups to address: State and local policy perspectives regarding
whether to require seat belts on school buses; information on the type
of seat belt system designs that are currently being offered on large
school buses; the economic impact that implementation of seat belt
requirements for school buses (including purchase and maintenance of
belts) have on States and local school districts; and the experience of
schools and States in training and educating children, parents and
drivers to use seat belts on large school buses.\5\ At the meeting,
participants requested that NHTSA provide up-to-date Federal guidance
on whether seat belts should be provided on school buses, and whether
lap belts should or should not be installed.
---------------------------------------------------------------------------
\4\ NHTSA also received written comments to docket 28103. We
will address all relevant issues raised in those comments in today's
NPRM and in a final rule or other rulemaking document following
today's NPRM.
\5\ A transcript of the July 11, 2007 public meeting is
available in docket 28103.
---------------------------------------------------------------------------
The agency has considered all of the comments made at the meeting.
NHTSA found the following views particularly helpful:
Mr. Charles Hood of the Florida Department of Education
related the State of Florida's experience with lap belts on school
buses. Informally, Mr. Hood estimated that the lap belt usage rate in
Florida was about 70 percent for elementary school students, 35 percent
for middle school students, and 25 percent for high school students.
Mr. Hood reported that vandalism and maintenance of the seat belts were
not major concerns. Mr. Hood estimated that the annual charge to equip
all of Florida's 1399 school buses with lap/shoulder belts would be
about $14 million.
Mr. Hood believed that the key point of the debate is
whether the three point belts will: Improve overall safety through the
crash protection improvements that they provide, or reduce overall
safety by potentially reducing the number of children who ride in
school buses. Mr. Hood stated that States that require lap belts need
Federal guidance as to whether they may or should continue to specify
lap belts in their school buses.
Ms. Ann Roy Moore of the Huntsville, Alabama City Schools
recommended that national agencies come up with some standards that
could be used to address the issue of school bus safety generally and
seat belt safety in particular.
Mr. Ken Hedgecock of Thomas Built Buses stated that two-
point belts are on 27 percent of the school buses Thomas Built
manufactures, and three-point belts are on 2 percent the school buses
that it manufactures. Mr. Hedgecock said that the greatest concern
relating to seat belts pertains to capacity and cost issues of the
three-point belt system. The reduction in capacity and incremental
costs of the three-point
[[Page 65512]]
system may have the unintended consequence of transporting fewer
children on the yellow school bus, thus negatively affecting the safety
of our nation's children. Mr. Hedgecock recommended the following as it
pertains to seat belts: Clarification is needed on the use of two-point
belt systems versus three-point belt systems in school buses;
clarification is needed on the designated seating position as it
pertains to a seat with seat belts; and there is a need for clear
performance standards for the integration of all systems: the school
bus, the seat, and the belts.
Mr. Steve Wallen of Safeguard, a division of Indiana Mills
Manufacturing Inc. (IMMI), stated that its testing shows that
compartmentalization does well in front and rear impact crashes, but
not particularly well in rollovers. Mr. Wallen recommends the FMVSSs
should be amended so as to allow for lap/shoulder belts while
maintaining compartmentalization to protect unbelted occupants. Mr.
Wallen suggested that the FMVSSs specify requirements such that a
school bus seat can withstand a crash with a student wearing a seat
belt and one behind not wearing a seat belt at the same time. Mr.
Wallen noted that retrofitting school buses is substantially more
expensive and difficult than installing seats in new buses.
Ms. Robin Leeds of the National School Transportation
Association (NSTA) stated that a Federal mandate is not appropriate
because of the costs. NSTA believes States and local school districts
are in a better position to determine the best use of their resources
than the Federal government. In the NSTA's view, the only way any
safety belt program can be successful is if it has the full commitment
of the school administration and of parents to make them work. NSTA
also recommended that NHTSA develop standards for voluntarily-installed
lap/shoulder belt systems so that ``everybody knows what system to use
when they do install those systems.''
a. NHTSA School Bus Research Results
Our guidance about seat belts on school buses also takes into
account the agency's research findings assessing the efficacy of
existing safety measures employed on school buses and possible
improvements to school bus occupant protection.
The Transportation Equity Act for the 21st Century (TEA-21)
directed NHTSA to study and assess school bus occupant safety and
analyze options for improvement. In response, the agency developed a
research program to determine the real-world effectiveness of FMVSS No.
222 requirements for school bus passenger crash protection, evaluate
alternative passenger crash protection systems in controlled laboratory
tests, and provide findings to support rulemaking activities to upgrade
the passenger crash protection for school bus passengers.
The research program consisted of NHTSA first conducting a full-
scale school bus crash test to determine a representative crash pulse.
The crash test was conducted by frontally impacting a conventional
style school bus (Type C) into a rigid barrier at 30 mph (48.3 km/h).
The impact speed was chosen to ensure that sufficient energy would be
imparted to the occupants in order to evaluate the protective
capability of compartmentalization, plus provide a level at which other
methods for occupant injury mitigation could be evaluated during sled
testing. A 30 mph (48 km/h) impact into the rigid barrier is also
equivalent to two vehicles of similar size impacting at a closing speed
of approximately 60 mph (96 km/h), which was found to be prevalent in
the crash database files.
In the crash test, we used Hybrid III 50th percentile adult male
dummies (representing adult and large teenage occupants), 5th
percentile adult female (representing an average 12-year-old (12YO)
occupant), and a 6-year-old child dummy (representing an average 6-
year-old (6YO) occupant). The dummies were seated so that they were as
upright as possible and as rearmost on the seat cushion as possible.
The agency evaluated the risk of head injury recorded by the dummies
(Head Injury Criterion (HIC15)), as well as the risk of chest (chest
G's) and neck injury (Nij),\6\ as specified in FMVSS No. 208 ``Occupant
crash protection.''
---------------------------------------------------------------------------
\6\ HIC15, Chest G, and Nij values are used to predict injury
risk in frontal crashes. HIC15 is a measure of the risk of head
injury, Chest G is a measure of chest injury risk, and Nij is a
measure of neck injury risk. The reference values for these
measurements are the thresholds for compliance used to assess new
motor vehicles with regard to frontal occupant protection during
crash tests, FMVSS No. 208. For HIC15, a score of 700 is equivalent
to a 30 percent risk of a serious head injury (skull fracture and
concussion onset). In a similar fashion, Chest G of 60 equates to a
20 percent risk of a serious chest injury and Nij of 1 equates to a
22 percent risk of a serious neck injury. For all these
measurements, higher scores indicate a higher likelihood of risk.
For example, a Nij of 2 equates to a 67 percent risk of serious neck
injury while a Nij of 4 equates to a 99 percent risk. More
information regarding these injury measures can be found at NHTSA's
Web site (http://www-nrd.nhtsa.dot.gov/pdf/nrd-11/airbags/rev_criteria.pdf).
---------------------------------------------------------------------------
NHTSA then ran frontal crash test simulations at the agency's
Vehicle Research and Test Center (VRTC), using a test sled to evaluate
passenger protection systems. Twenty-five sled tests using 96 test
dummies of various sizes utilizing different restraint strategies were
conducted that replicated the acceleration time history of the school
bus full-scale frontal impact test. The goal of the laboratory tests
was to analyze the dummy injury measures to gain a better understanding
of the effectiveness of the occupant crash protection countermeasures.
In addition to injury measures, dummy kinematics and interaction with
restraints (i.e., seat backs and seat belts, as well as each other)
were also analyzed to provide a fuller picture of the important factors
contributing to the type, mechanism, and potential severity of any
resulting injury.
NHTSA studied three different restraint strategies: (a)
compartmentalization; (b) lap belt (with compartmentalization); and,
(c) fore/aft loading.\7\
---------------------------------------------------------------------------
\7\ Unbelted occupants in the aft seat will affect the
kinematics of belted occupants in the fore seat due to seat back
deformation. Similarly, belted occupant loading of the fore seat
back thru the torso belt will affect the compartmentalization for
unbelted occupants in the aft seat.
---------------------------------------------------------------------------
Within the context of these restraint strategies, various boundary
conditions were evaluated: (a) Seat spacing--483 mm (19 inches), 559 mm
(22 inches) and 610 mm (24 inches); (b) seat back height--nominally 508
mm (20 inches) and 610 mm (24 inches); and, (c) fore/aft seat occupant
loading. Ten dummies were tested with misused or out-of-position (OOP)
lap or shoulder restraints. The restraints were misused by placing the
lap belt too high up on the waist, placing the lap/shoulder belt placed
behind the dummy's back, or placing the lap/shoulder belt under the
dummy's arm.
The agency found the following with regard to compartmentalization:
Low head injury values were observed for all dummy sizes,
except when override \8\ occurred.
---------------------------------------------------------------------------
\8\ Override means an occupant's head or torso translates
forward beyond the forward seat back providing compartmentalization.
---------------------------------------------------------------------------
High head injury values or dummy-to-dummy contacts beyond
the biofidelic range of the test dummy were produced when the large
male dummy overrode the seat in front of it, while the high-back seats
prevented this.
Low chest injury values were observed for all dummy sizes.
Based on dummy motion and interaction with each other,
compartmentalization was sensitive to seat back height for the 50th
percentile male dummy.
Compartmentalization of 6YO and 5th percentile female
dummies did not
[[Page 65513]]
appear to be sensitive to rear loading conditions.
Compartmentalization of the 50th percentile male dummy did
not appear to be sensitive to seat spacing for the 50th percentile male
dummy.
The agency found the following with regard to lap belts on large
school buses:
Head and chest injury values were low for all dummy sizes.
The average neck injury value was above the injury
assessment reference value (IARV) for all test dummies, and was 70
percent above for the 5th percentile female dummy.
Neck injury values increased for the 5th percentile female
dummy when the seat spacing was increased from 483 mm (19 inches) to
559 mm (22 inches).
The agency found the following with regard to properly worn lap/
shoulder belts on school buses:
Head, chest and neck injury values were low for all size
dummies and below those seen in the compartmentalization and lap belt
results.
Average head injury values were, at most, about half those
seen in the compartmentalization and lap belt results.
Neck injury values increased with application of rear
loading for the 6YO and 5th percentile female dummies.
Lap/shoulder belt systems would require approximately 15
inches seat width per passenger seating position. The standard school
bus bench seat is 39 inches wide, and is considered a three-passenger
seat. If the width of the seat bench were increased to 45 inches for
both seats on the left and right side of the school bus, the aisle
width would be reduced to an unacceptable level.
NHTSA found that, for improperly worn lap/shoulder belts:
Placing the shoulder belt behind the dummy's back resulted
in dummy motion and average dummy injury values similar to lap belt
restraint.
Placing the shoulder belt under the dummy's arm provided
more restraint on dummy torso motions than when the belt is placed
behind the back. Average dummy injury values for the 6YO were about the
same as seen with lap/shoulder belts and 5th percentile female dummy
injury values were between those seen in lap/shoulder belts and lap
belts.
b. Agency Recommended Best Practices
School buses are one of the safest forms of transportation in the
U.S. Every year, approximately 474,000 public school buses,
transporting 25.1 million children to and from school and school-
related activities,\9\ travel an estimated 4.8 billion route miles.\10\
Over the 11 years ending in 2005, there was an annual average of 26
school transportation related fatalities (11 school bus occupants
(including drivers and passengers) and 15 pedestrians).\11\ The bus
occupant fatalities were comprised of six school-age children, with the
remaining being adult drivers and passengers.\12\ On average, there
were 9 crashes per year in which an occupant was killed. The school bus
occupant fatality rate of 0.23 fatalities per 100 million vehicle miles
traveled (VMT) is more than six times lower than the overall rate for
motor vehicles of 1.5 per 100 million VMT.\13\
---------------------------------------------------------------------------
\9\ School Transportation News, Buyers Guide 2007.
\10\ This value was reported by School Bus Fleet 2007 Fact Book.
\11\ ``Traffic Safety Facts--School Transportation Related
Crashes,'' NHTSA, DOT HS 810 626. The data in this publication
account for all school transportation-related deaths in transporting
students to and from school and school related activities. This
includes non-school buses used for this purpose when these vehicles
are involved in a fatal crash.
\12\ For the crashes resulting in the 11 annual school bus
occupant fatalities, 51 percent of the fatalities and 52 percent of
the crashes were from frontal collisions. Traffic Safety Facts 2005,
School Transportation-Related Crashes, DOT HS 810 626.
\13\ Traffic Safety Facts 2005, DOT HS 810 631.
---------------------------------------------------------------------------
The agency's school bus research results indicated that lap/
shoulder belts could enhance the safety of large school buses, such
that a child who has a seat on the school bus and who is belted with a
lap/shoulder belt on the bus would have an even lower risk of head and
neck injury than on current large school buses.\14\ Thus, if ample
funds were available for pupil transportation, and pupil transportation
providers could order and purchase a sufficient number of school buses
needed to provide school bus transportation to all children, we would
recommend that pupil transportation providers consider installing lap/
shoulder belts on large school buses because of the enhancements that
lap/shoulder belts could make to school buses. Realistically, however,
we recognize that funds provided for pupil transportation are limited,
and that the monies spent on lap/shoulder belts on large school buses
would usually draw from the monies spent on other crucial aspects of
school transportation, such as purchasing new school buses to ensure
that as many children as possible are provided school bus
transportation, on driver and pupil training on safe transportation
practices, and on upkeep and maintenance of school buses and school bus
equipment. Bearing these considerations in mind, we recommend that
pupil transportation providers consider lap/shoulder belts on large
school buses only if there would be no reduction in the number of
children that are transported to or from school or related events on
large school buses. Reducing bus ridership would likely result in more
student fatalities, since walking and private vehicles are less safe
than riding a large school bus without seat belts.
---------------------------------------------------------------------------
\14\ The TEA-21 research program did not study whether belts
could enhance the protection of compartmentalization in side crashes
and rollovers. Most school bus fatalities occur in a crash involving
a rollover, and the side crash fatalities are about as frequent as
front crash fatalities.
---------------------------------------------------------------------------
Our best practices recommendation seeks to reflect real world
considerations about the safety record of school buses, the economic
impact on school systems incurred by the costs of seat belts and the
impact that lap/shoulder belts have on the seating capacity of large
school buses. Our laboratory test results indicate that our test
dummies measured better head protection performance when lap/shoulder
belts were properly used with compartmentalization than compared to
compartmentalization alone. However, best practices compel us to
acknowledge that installation of lap/shoulder belts, as currently
designed, reduce the number of seats offered to students, resulting in
fewer children riding school buses, exposing more children to higher
safety risks in alternative forms of transport to or from school or
related events, and a probable overall net safety disbenefit due to
their installation.
Best practices compel us to encourage pupil transportation
providers to make a comprehensive analysis of their needs and determine
how lap/shoulder belts on large school buses accord with those needs.
The best practices approach we have developed allows States the leeway
to decide whether to require seat belts on large school buses, and
whether lap only or lap/shoulder belts should be ordered. Given the
tradeoff noted above, States should be permitted the flexibility of
deciding whether to order large school buses with the seat belt safety
enhancements after considering the excellent safety record of large
school buses with compartmentalization, the benefits of allocating
resources to belts as opposed to alternative safety measures, and the
means available to ensure that the belts would be used. If a State were
to determine that lap/shoulder belts are in its best interest, NHTSA
encourages the State to install those systems. Today's document
proposes performance requirements for the lap/shoulder belts, to ensure
they will work well in a crash even if voluntarily installed.
[[Page 65514]]
Certain highway safety grant funds may continue to be used to fund
the purchase and installation of seat belts (lap or lap/shoulder) on
school buses. Annually, all States, the District of Columbia, Puerto
Rico, the Bureau of Indian Affairs, and the U.S. territories receive
NHTSA Section 402 State and Community Highway Safety Formula Grant
Funds. A wide range of behavioral highway safety activities that help
reduce crashes, deaths, and injuries, including seat belt-related
activities, qualify as eligible costs under the Section 402 program.
Each State determines how to allocate its funds based on its own
priorities and identified highway safety problems as described in an
annual Highway Safety Plan (HSP).
As with all proposed expenditures of Section 402 funds, the
purchase and installation of seat belts on school buses must be
identified as a need in the State's HSP and comply with all
requirements under 23 U.S.C. Part 1200. Section 402 funds may not be
used to purchase the school bus in its entirety, but may fund only the
incremental portion of the bus cost directly related to the purchase
and installation of seat belts.
We would advise States that are considering purchasing seat belts
for school buses to be guided by the proposed standards in this notice
of proposed rulemaking.
c. Guidance on Lap Belts on Large School Buses
In the July 11, 2007 public meeting, some participants asked for
guidance on whether lap belts should be prohibited on large school
buses. The question was asked in the aftermath of school bus research
studies that found lap belts were associated with increased risk of
injury on large school buses.\15\
---------------------------------------------------------------------------
\15\ See the results of NHTSA's school bus research program
(Report to Congress, School Bus Safety: Crashworthiness Research,
supra). In addition, a 1985 study by Transport Canada provided data
comparing the reaction of three belted and three unbelted 5th
percentile adult female anthropomorphic test dummies in a 48 km/h
(30 mph) frontal collision of a large school bus meeting
compartmentalization requirements. The results indicated that the
belted dummies experienced higher head accelerations, lower chest
accelerations and more severe neck extension than did the unbelted
ones. Accordingly, the study concluded that the use of a lap belt
system in a school bus ``may result in more severe head and neck
injuries for a belted occupant than an unbelted one, in a severe
frontal collision.'' (School Bus Safety Study, January 1985). After
analyzing the Transport Canada study, NHTSA could not conclude from
the report's findings that belts degraded the benefits of
compartmentalization to the extent that the supplemental restraint
system rendered inoperative the safety of large school buses, but
NHTSA acknowledged that the possibility exists that the occupant
kinematics shown in the Canadian tests could occur. (Docket No. 85-
14; Notice 02, RIN 2127-AB84, March 22, 1989).
---------------------------------------------------------------------------
After considering the data and other information on lap belts on
large school buses, NHTSA does not believe there is a need to prohibit
lap belts on the buses. In its 1999 report on bus crashworthiness, the
NTSB concluded that the compartmentalization requirement for school
buses in FMVSS No. 222 is incomplete in addressing school bus occupant
protection in rollovers and lateral impacts from large vehicles, in
that in such crashes, passengers do not always remain completely within
the seating compartment. Although we have not found a safety need
exists with respect to those non-frontal crashes to warrant requiring
seat belts on large school buses,\16\ we have always permitted States
to choose to require the belts over and above the Federally required
compartmentalization in the school buses they purchase.
---------------------------------------------------------------------------
\16\ We reiterate our conclusion that the overall potential
benefits of requiring lap belts on large school buses are
insufficient to justify a Federal requirement for mandatory
installation. NAS has also suggested that the funds used for
required seat belts might be better used in other school bus safety
programs. Special Report 222 (1989), supra.
---------------------------------------------------------------------------
We realize that laboratory research, including our own on lap
belted dummies, shows relatively poor performance of lap belts in large
school buses. However, this research involved severe frontal impacts.
We cannot make a determination, based on the results of the limited
testing with lap belt restraints in a severe frontal crash condition,
that the addition of lap belts in large school buses reduces overall
occupant protection. Lap belts are required in three States (New York
(1987), New Jersey (1994), Florida (2001)), in many other school
districts, and in special-needs equipped school buses. NHTSA has
examined in depth New York State school bus crash data for lap belt
equipped and non-belt equipped buses, and could not conclude that lap
belts either helped or hurt occupant injury outcomes.
VI. Proposed Upgrades to Occupant Crash Protection
After considering the findings of NHTSA's school bus research
program, we have decided to issue this NPRM to propose several sets of
upgrades to the school bus safety requirements. The first set of
upgrades involves improving the compartmentalized school bus interior
on both small and large school buses. Seat back height would be
increased from 20 inches to 24 inches to reduce the potential for
passenger override in a crash, and school buses with seat bottom
cushions that are designed to flip-up, typically for easy cleaning,
would need a self-latching mechanism. The proposal to raise seat back
height responds to findings from the agency's school bus research
program, while the proposal for self-latching mechanisms responds to an
NTSB recommendation to NHTSA (H-84-75).
The second set of upgrades involves specifics about the occupant
protection requirements required for passengers of small school buses
(school buses with a GVWR of 10,000 lb or less). In response to NHTSA's
school bus research findings, this NPRM proposes to require small
school buses to have lap/shoulder belts instead of just lap belts. The
lap/shoulder belts would have to fit all passengers ages 6 through
adult, and be equipped with retractors. The lap/shoulder belts would
have to meet the existing anchorage strength requirements for lap/
shoulder belts in FMVSS No. 210 and would be subject to new
requirements for belt anchor location and torso belt adjustability.
FMVSS No. 207 would also be amended to apply to passenger seats in
small school buses. A newly-developed ``quasi-static'' test requirement
(discussed in the next section of this preamble) would be adopted into
FMVSS No. 222 to test school bus seats with lap/shoulder belts, to help
ensure that seat backs incorporating lap/shoulder belts are strong
enough to withstand the forward pull of the torso belts in a crash and
the forces imposed on the seat from unbelted passengers to the rear of
the belted occupants. These requirements would add to existing
compartmentalization requirements for seat performance (e.g., seat
performance forward, S5.1.3 of FMVSS No. 222, and seat performance
rearward, S5.1.4). A minimum seat belt width of 15 inches would be
specified for all school bus seats with lap/shoulder belts.
The third set of upgrades involves requirements for voluntarily-
installed seat belts on large school buses. For large school buses with
voluntarily-installed lap/shoulder belts, the vehicle would be subject
to the requirements described above for lap/shoulder belts on small
school buses, except FMVSS No. 207 would not apply to the passenger
seats. The quasi-static test procedures for small school buses would
slightly vary from those applying to seats on large school buses with
voluntary lap/shoulder belts, to account for crash characteristic
differences of large school buses versus small school buses. (Due to
the mass and other characteristics of the vehicles, in crashes small
school buses are subject to
[[Page 65515]]
higher severity forces than large school buses.)
For large school buses with voluntarily-installed lap belts, the
vehicles would be required to meet FMVSS No. 210 requirements of a
loading force of 22,240 N (5,000 pounds) per seating position. This
would be consistent with the existing lap belt loading requirement for
small school buses and light vehicles with lap belt only systems.
These proposed requirements are discussed below.\17\ In addition,
NHTSA has prepared a Technical Analysis that, among other things,
presents a detailed analysis of data, engineering studies, and other
information supporting these proposals.\18\ A copy of this Technical
Analysis will be placed in the docket.
---------------------------------------------------------------------------
\17\ In Appendix A to this preamble, we list the FMVSSs affected
by this NPRM and the proposed amendments to those standards.
\18\ NHTSA Technical Analysis to Support Upgrading the Passenger
Crash Protection in School Buses (September 2007).
---------------------------------------------------------------------------
a. Improving the Compartmentalized School Bus Interior of Both Small
and Large School Buses
Seat back height. At present, school bus seat back height
is specified at S5.1.2 of FMVSS No. 222 to be at a minimum 508
millimeters (mm) (20 inches (in)). In this NPRM, we propose that the
minimum seat back height for school bus seats be raised to 610 mm (24
in).
In NHTSA's school bus research program, when dummies representing
older students were compartmentalized with current 20-inch high seat
backs, the dummies were much more likely to override the seat and make
head contact with test dummies that were placed in seats forward of the
dummies. While the injury potential of these contacts was not
quantifiable, dummies overriding seats means that the
compartmentalization was not working. The highest HIC 15 value was
registered when a 50th percentile male dummy behind a 20-inch seat back
contacted the seat back two rows ahead. In cases where incidental
contact did occur, the HIC 15 values tended to be very high. In two
cases, the HIC 15 values were over 2,000 and the third was over 5,000.
For the 24-inch seat backs, there was only dummy interaction between
the rows of seats if both the forward and rearward dummies were 50th
percentile male dummies. The high seat back seats effectively prevented
the passengers from overriding the seat backs.
In the past, NHTSA has been informed that with the higher seat
backs, drivers are not able to see and supervise the children. However,
NHTSA is not aware of data showing that the higher seat backs result in
supervision problems. NHTSA notes that four states (Illinois, New
Jersey, New York, and Ohio) plus many other school districts require
their school bus seats to have 24-inch seat backs. These states
represent about 20 percent of all students in public transportation. We
have received no reports of supervisory or safety related issues
resulting from the higher seat backs from these jurisdictions. We
request public comment on this issue.
Restraining barrier height. We propose to amend S5.2.2,
``Barrier position and rear surface area,'' to specify that the rear
surface area of the restraining barrier shall be such that in the front
projected view, the restraining barrier's surface area above the
horizontal plane that passes through the seating reference point, and
below the horizontal plane 610 mm (24 inches) above the seating
reference point, shall be not less than 90 percent of the seat bench
width in millimeters multiplied by 610 (inches multiplied by 24). We
are also proposing that restraining barriers have a minimum width of 75
percent of the seat bottom cushion at the upper portion of the
restraining barrier. This is needed to ensure that the restraining
barrier has sufficient width and area so that it sufficiently restrains
passengers. Further, we seek to clarify that the restraining barrier's
perimeter need not coincide with or lie outside of the perimeter of the
seat back of the seat for which it is required if that seat back is
higher than the minimum required by FMVSS No. 222. (Such a position
would be consistent with an April 8, 1977 NHTSA interpretation letter
to Wayne Corporation.)
Seat cushion latches. At present, FMVSS No. 222 at S5.1.5
requires seat bottom cushions to withstand an upward force that is five
times the weight of the seat bottom cushion. S5.1.5 specifies that,
with all manual attachment devices between the seat and the seat
cushion in the manufacturer's designated position for attachment, the
seat cushion shall not separate from the seat at any attachment point
when subjected to an upward force in Newtons of 5 times the mass of the
seat cushion in kilograms and multiplied by 9.8 m/s\2\, applied in any
period of not less than 1 nor more than 5 seconds, and maintained for 5
seconds.
This text of S5.1.5 has remained unchanged since 1976. NHTSA notes
that in order to allow the cushion to be removed or flipped up for
maintenance, some seat cushions have been designed to attach to the
rear seat frames with clips that swivel on and off the frame and with
stationary clips that slip under the front frame member. Such cushion
designs meet S5.1.5.
In 1984, the National Transportation Safety Board (NTSB) issued a
recommendation to NHTSA (H-84-75) that seat cushions be attached with a
fail-safe latching device to ensure that the cushions remain in their
installed position during impacts and rollovers. This recommendation
was closed based on a 1987 survey of NHTSA school bus manufacturers
which indicated that the manufacturers would voluntarily implement the
NTSB recommendation. Data indicate, however, that the school bus
manufacturers did not voluntarily implement the NTSB recommendation.
NTSB believes there was a safety need for a requirement for a
latching device because a 1987 NTSB study reported that seat cushions
came loose in 16 of 44 school bus crashes. In four of the 16 crashes,
all of the seat cushions came loose, and minor injuries were caused by
the loose seat cushions in three of the 16 crashes. The NTSB concluded
that seat cushions came free because clips were not secured to the seat
frame or were loose and free to rotate. The 1987 report indicated the
following safety concerns associated with loose cushions: Flying
cushions can strike and injure occupants; occupants can fall through
the opening left by the cushion; loose cushions may block exit routes;
and loose cushions may hide injured occupants.
In the agency's school bus research program, seat cushions became
detached in the frontal crash of a large school bus. To address the
safety concerns raised by the NTSB, NHTSA is proposing to amend S5.1.5
to require latching devices for school bus seats that have latches that
allow them to flip up or be removed for easy cleaning. We also propose
a test procedure that would require the latch to activate after a 22 kg
(48 lb) mass is placed on top of the seat at the seat cushion's center.
The 48 lb weight is that of an average 6-year-old child. The test would
ensure that any unlatched seat cushion would latch when a child
occupant sits on the seat.
b. Additional Occupant Protection Requirements for Small School Buses
(School Buses With a GVWR of 4,536 kg (10,000 lb) or Less)
The agency proposes that small school buses be required to
have lap/shoulder belts at all passenger seating positions. Since the
FMVSSs were first promulgated, small school buses passenger seats have
been required to have passenger lap belts (defined as Type 1 belts in
FMVSS No. 209) as
[[Page 65516]]
specified in FMVSS No. 208, that meet the lap belt strength
requirements specified in FMVSS No. 210. Lap belts were required
because the ratio of the mass of a potential collision partner to that
of a small school bus is larger than for a large school bus. Thus, for
vehicle-to-vehicle collisions, the deceleration of a small school bus
will be greater than for a large school bus. However, before today, we
have never sought to require lap/shoulder belts for all passenger seats
in small school buses.\19\
---------------------------------------------------------------------------
\19\ FMVSS No. 208 (S4.4.5) requires buses, other than school
buses, with a GVWR of 10,000 lb or less manufactured on or after
September 1, 2007 to have lap/shoulder belts (Type 2 belts) at all
passenger seating positions other than side-facing positions.
Today's NPRM would be consistent with that requirement for the non-
school buses. (We note that the heading of S4.4.5 of FMVSS No. 208
should specify that the section does not apply to small school
buses. See http://dmses.dot.gov/docimages/pdf89/293807_web.pdf,
NHTSA letter February 19, 2004, explaining the typographical error.
Today's NPRM would correct the typographical error in S4.4.5.)
---------------------------------------------------------------------------
The primary reason for proposing lap/shoulder belts is the
increased level of protection that children riding in a small school
bus gain by having a lap/shoulder belt. Lap/shoulder belts provide an
increased level of protection from lap belts by reducing the potential
of head and neck injuries in frontal impacts. The relatively poor
performance of lap belted dummies in NHTSA's frontal sled test research
is of greater concern for small school buses. Frontal crashes will tend
to be more severe for these smaller school buses than for large school
buses. Properly worn lap/shoulder belts will reduce the potential
negative effects of lap belts in severe frontal crashes while
maintaining and potentially enhancing the protection offered in other
crash modes. In NHTSA's 2002 Report to Congress, School Bus Safety:
Crashworthiness Research, NHTSA noted that the results of the
electronic data and video data showed that the dummies restrained with
lap and shoulder belts had a lower risk of head and neck injuries than
unbelted dummies.
Finally, while installation in large school buses could result in a
17 percent reduction in seating capacity, small school buses are
already configured with seating positions that can accommodate lap/
shoulder belts without a reduction in seating capacity.\20\
---------------------------------------------------------------------------
\20\ The typical seating configuration of small school buses is
based on five rows of 762 mm (30 inches) two passenger seats.
Therefore, the installation of lap/shoulder belts into each seating
position should not result in a reduction in capacity.
---------------------------------------------------------------------------
Adjustability of the belt system. NHTSA proposes that
requirements be added to FMVSS No. 210 that would ensure that the seat
belt anchorages on school bus seats are designed so that the belt
system will properly fit the range of children on a school bus: The
average 6-year-old (represented by the Hybrid III 6-year-old child
dummy (45 inches tall/52 pounds)); the average 12-year-old (represented
by the Hybrid III 5th percentile female dummy (59 inches/108 pounds))
and; the large high school student (represented by the 50th percentile
adult male dummy (69 inches/172 pounds)). Proper fit for children
prevents injury and would ensure that the system performs properly in a
crash. In addition, if the lap/shoulder seat belts did not fit the
child occupant properly, there is an increased likelihood that the
child would misuse the lap/shoulder belt system by placing the shoulder
portion under the arm or behind the back. NHTSA's school bus research
results showed that when the shoulder belt was placed behind the back,
the restraint system functioned like a lap belt. Lap belts produced a
higher risk of neck injury in the testing program.
In the agency's school bus research program, we saw examples of
improper seat anchorage location. The first set of lap/shoulder belt
seats supplied for testing in the school bus research program did not
have the anchorages of the lap/shoulder belts located so that the seat
belts would fit appropriately on any of the test dummies. The torso
belt came across the dummies' heads and necks and the lap belt was high
on the abdomen instead of on the hips. After consultation with the seat
manufacturer, a second set of lap/shoulder belt equipped seats had seat
belt anchorages such that the seat belts fit all of the test dummies
(6-year-old to 50th percentile male) properly. The torso belt anchorage
was higher on the seat back to allow for proper placement of the torso
belt on taller people.\21\ Also, as in the previously supplied seats,
the shoulder belt had an adjustable anchorage that slides up and down a
second shoulder belt so it could properly adjust for the sitting height
of the typical 6-year-old through the adult size passenger.
---------------------------------------------------------------------------
\21\ A torso belt anchorage located below the adult dummy's
shoulder may increase the spinal compression loading in a crash,
would increase the risk of the dummy sliding under the belt in a
crash, and would increase the risk of spinal and abdominal injuries.
The allowable location for the shoulder belt is specified in Figure
1 of the current FMVSS No. 210.
---------------------------------------------------------------------------
NHTSA has tentatively determined that design requirements for the
seat belt anchorages should be specified such that the belts would be
sure to fit occupants ranging in size from the average 6-year-old child
to the average adult male. The anchorage locations were determined by
placing test dummies (6-year-old, 5th percentile female and 50th
percentile male) into the school bus seats. The results are reported in
NHTSA's Vehicle Research Test Center (VRTC) Test Report, Test
Methodology for Lap/Shoulder Belts in School Buses. NHTSA has
tentatively decided to apply the location requirements of FMVSS No.
210, S4.3.1. See Figure 1 of this preamble, below.
In addition, for the reasons discussed in the agency's technical
report supporting this NPRM, we propose that school bus seats with lap/
shoulder belts have a minimum shoulder belt adjustment range between
280 mm (11 inches) above the seating reference point and the school bus
torso belt anchor point, to ensure that the shoulder belt will fit
passengers ranging in size from a 6-year-old child to a 50th percentile
adult male.
BILLING CODE 4910-59-P
[[Page 65517]]
[GRAPHIC] [TIFF OMITTED] TP21NO07.000
BILLING CODE 4910-59-C
The agency also proposes that the seat belt anchorages,
both torso and lap, be required to be integrated into the seat
structure. NHTSA proposes such integration because if we do not, we are
concerned that some manufacturers could incorporate some seat belt
anchorages into the bus floor, sidewall, or roof. Such installation
into places other than the seat structure could potentially injure
unbelted school bus passengers in a crash, or obstruct passengers
during emergency egress. However, we seek comment on whether there are
torso and lap belt anchorage designs available, other than integrated
into the seat back, that would not impede access to emergency exits or
become an injury hazard to unbelted passengers.
Improperly designed lap belts include those in which the buckle
stalk is too long and the lap belt portion of the belt assembly rides
high on the 6-year-old child's abdomen. For a proper fit, the lap belt
portion must fit low across the hips so that the crash loads are
distributed across the pelvis and not the abdominal area. Loading of
the abdomen rather than the pelvis increases the risk of internal
injuries caused by the seat belt penetration into the soft tissue of
the abdomen.
We are aware that lap belts supplied to some states have a long
buckle end
[[Page 65518]]
that causes the lap belt to not fit low across the hips of the
passengers. The long buckle end also causes problems with securing
child restraints.\22\ However, our understanding is that long buckle
ends have been provided out of a privacy concern about school bus
personnel fastening lap belts near the crotch area of young passengers.
Comments are requested on whether long buckle stalks should be retained
on lap belts because of the privacy issues, even if the long buckle
stalks may result in misplacement of the lap belt across the child's
abdomen and difficulty in child restraint attachment.
---------------------------------------------------------------------------
\22\ The short buckle length is recommended in NHTSA's pamphlet
on the Proper Use of Child Safety Restraint Systems in School Buses.
http://www.nhtsa.dot.gov/people/injury/buses/busseatbelt/index.html.
---------------------------------------------------------------------------
Seat belt anchor strength for lap/shoulder belts. Small
school buses have been required to have lap belts since the issuance of
FMVSS No. 222. The anchorages for these lap belts have had to be
certified to FMVSS No. 210. Standard No. 210 specifies that for
multiple seat belts anchored to the same seat, the belts are pulled
simultaneously.
In today's proposal to require lap/shoulder belts in small school
buses, we propose that small school buses should meet the existing
small school bus anchorage strength requirements for lap/shoulder belts
in FMVSS No. 210. Those existing strength requirements, specified in
S4.2.2 for lap/shoulder belt anchorages, specify that the torso portion
of the lap/shoulder belt be tested simultaneously with the lap belt
portion at 13,344 N (3,000 pounds) each for each belt loop. For
example, a three-position school bus seat is required to withstand an
80 kN (18,000 pound) test load. The calculation for the seat belt
anchorage load requirement in a three passenger seat is (three times
the shoulder belt plus three times the lap belt applied simultaneously)
= ((3 x 13,344 N) + (3 x 13,344 N)) = 80,064 N (18,000 pounds).
Seat belt retractors. For school bus seat belts, there is
at present no requirement for seat belt retractors. This is because the
only seat belt systems currently installed in school buses are lap
belts where retractors are not needed for the seat belt system to
function properly. We propose to add a new section of regulatory text
(S7.1.5 to FMVSS No. 208) to ensure that retractors are provided for
school bus lap/shoulder seat belt assemblies, and that the retractors
meet the same requirements as seat belt retractors for passenger cars,
trucks and multipurpose passenger vehicles.
Maximum number of lap/shoulder seat belts and minimum seat
width. In S4.1 of FMVSS No. 222, NHTSA currently considers the number
of seating positions on a bench seat to be the width of the bench seat
in millimeters (W), divided by 381 and rounded to the nearest whole
number. This W value is used to calculate the compartmentalization
requirements for seat backs on all school buses and the number of lap
belt only seating positions that must meet the provisions of FMVSS No.
208 and 210 for small school buses. The agency will continue to
consider W to be the number of seating positions per bench seat with
optional provided lap belts on large school buses as well as the
compartmentalization requirements for all school buses, except that the
divisor will be 380 rather than 381. (Using 380 instead of 381 would
just be for simplicity.) However, for the seating positions on small
school buses with required lap/shoulder belts and on large school buses
with optional lap/shoulder belts, we are defining the number of seating
positions (Y) in a slightly different way. Y is the total seat width in
millimeters divided by 380, rounded down to the nearest whole number.
Under the definitions of W and the proposed definition of Y, a 1,118 mm
(44 inch) wide seat would have W = 3 seating positions for the purposes
of calculating the magnitude of the compartmentalization requirements
to apply to the seat back, but only Y = 2 seating positions for
determining the lap/shoulder belts installed on the seat.\23\ The
result of this ``Y'' calculation would be that each passenger seating
position in a school bus seat with a lap/shoulder belt would have a
minimum seating width of 380 mm (15 inches). A proposed minimum seating
position width of 15 inches for seats with lap/shoulder belts is needed
because school buses are typically purchased based on maximum seating
capacity, and we seek to ensure that manufacturers will not install
lap/shoulder belt anchorages that are so narrowly spaced that they
would only fit the smallest occupants.
---------------------------------------------------------------------------
\23\ ``Y'' would also be used to determine the loads to be
applied to the shoulder belts for the quasi-static test, discussed
below in this preamble. See also paragraphs S5.1.6.5.5(a) and (b) of
the proposed regulatory text.
---------------------------------------------------------------------------
FMVSS No. 207, Seating Systems. At present, FMVSS No. 207
specifically excludes all bus passenger seats from its general
performance requirements. FMVSS No. 207 tests the forward strength of
the seat attachment to the vehicle by replicating the load that would
be applied through the seat center of gravity by inertia in a 20 g
vehicle deceleration. If seat belt anchors are attached to the seat,
FMVSS No. 207 requires that the FMVSS No. 210 anchorage load be applied
at the same time the FMVSS No. 207 inertial load is applied. Both loads
are applied simultaneously because during a crash, the seat with an
integrated seat belt (such as the seat in a school bus) will have to
sustain the loading due to both the seat mass and the seat belt load
from the restrained occupant.
The agency is proposing to apply FMVSS No. 207 to small school
buses with lap/shoulder belts because the load imposed by FMVSS No. 207
appears to be greater than the load that would be imposed by FMVSS No.
222's seat performance requirements (S5.1.3). If we assume a seat mass
of 35 kg (77 pounds),\24\ the FMVSS No. 207 load would be 6,867 N
(1,544 pounds). For a school bus seat with two seating positions, the
FMVSS No. 210 load would be a total of 53,376 N (12,000 pounds). So if
FMVSS No. 207 were applied it would add 12 percent [((53,376 N + 6,867
N)/53,376 N) - 1)] to the total load. This would result in a more
stringent test procedure. Comments are requested on whether FMVSS No.
207 should be applied to small school bus passenger seats.
---------------------------------------------------------------------------
\24\ A 991 mm (39 inch) wide C.E. White seat weights 34.5 kg (76
pounds). See www.cewhite.com/cr-series-prod_info.html.
---------------------------------------------------------------------------
A newly-developed ``quasi-static'' test requirement would
apply to test school bus seats with lap/shoulder belts to ensure that
the top of the seat back incorporating the seat belt anchorage does not
pull too far forward due to the torso belt loading of the belted
occupant and jeopardize the protection of unbelted passengers to the
rear of the belted occupants. The quasi-static test is discussed in the
next section. The quasi-static test requirements would be in addition
to existing compartmentalization requirements for seat performance
(e.g., seat performance forward, S5.1.3 of FMVSS No. 222, and seat
performance rearward, S5.1.4), and would be in addition to the FMVSS
No. 210 test for the seat belt anchorages, and would be in addition to
the FMVSS No. 207 test. A new school bus seat (test specimen) would be
used for each of these tests.
c. Additional Occupant Protection Requirements for Large School Buses
With Voluntarily-Installed Lap/Shoulder Seat Belts
Large school buses with voluntarily-installed lap/shoulder
seat belts would be subject to the
[[Page 65519]]
requirements described above for lap/shoulder belts on small school
buses, except FMVSS No. 207 would not apply to the passenger seats,\25\
and as explained in the next section, the quasi-static test procedures
for small school buses would slightly vary from those applying to seats
on large school buses with voluntary lap/shoulder belts, to account for
the relative severity of the anticipated frontal crash conditions for
each school bus type.
---------------------------------------------------------------------------
\25\ The agency does not believe there is a need to apply FMVSS
No. 207 to large school buses that do not have seat belts because
the load imposed by 207 appears to be lower than the load that would
be imposed by FMVSS No. 222's seat performance requirements
(S5.1.3). Under FMVSS No. 222, there are two forward forces applied
to the seat back, by a lower bar and an upper bar. The lower bar
force has a maximum value of 3,114 N (700 pounds) times the number
of seating positions. In the seat performance (forward strength)
test, after its initial application, the lower bar load is then
reduced by half, and then the loading bar is locked in place.
Following this, the upper loading bar is applied. The upper loading
bar force must stay in a force deflection curve that has a minimum
value of 4,448 N (1,000 pounds) and a maximum of 10,676 N (2,400
pounds) once the loading bar displaces more than 127 mm (5 inches).
If we assume a load in the middle of the force/deflection range, the
total forward force on the seat back is 7,562 N (1,700 pounds). In
comparison, if we assume a seat mass of 35 kg (77 pounds), the FMVSS
No. 207 inertial loading applied to this school bus seat would be
6,867 N (1,544 pounds). Thus, the FMVSS No. 222 forward seat
strength loads for a large school bus are a reasonable substitute
for the FMVSS No. 207 inertial loads. Likewise, the agency does not
believe there is a need to apply FMVSS No. 207 to large school buses
that do have seat belts. The agency is proposing FMVSS No. 210 seat
belt anchorage loads for large school buses, and has found that the
proposed loads are in excess of peak loads that were applied to the
attachment of the seat to the sled test fixture in a 12 to 13 g sled
test simulating a large school bus barrier crash. Thus, this load
measurement captured the inertial loading of the seat. It can
therefore be argued that for large school bus seats, the proposed
FMVSS No. 210 anchorage loading would exceed loading that
incorporates the seat inertial loading, albeit at a lower
deceleration level than the 20 g value required by FMVSS No. 207.
---------------------------------------------------------------------------
The agency proposes that for large school buses with voluntarily
installed lap/shoulder seat belts, the FMVSS No. 210 anchorage strength
requirement should be identical to the requirements for passenger seat
belt anchorages in smaller vehicles. We are not aware of any
practicability concerns with meeting such anchorage strength
requirements since the proposed level of performance for large school
buses is already required of all other vehicles to which FMVSS No. 210
applies. For lap/shoulder belts, the torso and body blocks will be
pulled at 13,334 N (3,000 pounds).
However, the agency recognizes that large school bus vehicles
experience lower crash forces in the passenger compartment than do
small school buses and other passenger motor vehicles. Part of the
reason for the difference in crash deceleration is that the large bus
body is designed to slide relative to the underlying frame as observed
in the frontal barrier crash test. Specifically, the large school bus
experienced about 12-13 g peak deceleration during a 48.3 km/h (30 mph)
frontal crash into a rigid barrier, compared to about 25 g for a small
school bus. In real world vehicle-to-vehicle crashes, large school
buses will also experience lower crash forces than would a small school
bus in a similar crash. This difference is due to the greater mass of
the large bus and consequent lower change in crash forces.
During the development of this NPRM, NHTSA measured the dynamic
loads to the seat belt anchorages on lap/shoulder belt-equipped two-
passenger school bus seats from C.E. White Corporation and IMMI during
crash simulation sled testing. The forces on the seat anchorages were
measured using load cells attached to the sled buck and the attachment
locations of the seat structure. The test was conducted using the 48.3
km/h (30 mph) school bus crash pulse that was used in the school bus
research program. The seats had two 50th percentile adult male dummies
restrained in lap/shoulder belts and two unbelted 50th percentile adult
male dummies that struck the seat back.
The total loads for both seating positions transmitted from the
lap/shoulder belts, through the seat structure and anchorages to the
floor for each seat are shown in Figures 2 and 3 for the C.E. White and
IMMI seats, respectively. The highest loads experienced by the C.E.
White seats revealed that the force was approximately 17,500 N (3,934
pounds) per seating position.
[[Page 65520]]
[GRAPHIC] [TIFF OMITTED] TP21NO07.001
[GRAPHIC] [TIFF OMITTED] TP21NO07.002
[[Page 65521]]
This testing suggested that the total peak dynamic loading
sustained by the seat belts was about \2/3\ of that applied in FMVSS
No. 210. Notwithstanding the above data, the agency believes that the
anchorage strength provided by FMVSS No. 210 provides the foundation
for seat belt performance and there is value in maintaining consistency
in this foundation. We understand that this higher factor of safety may
result in seats and anchorages being constructed with heavier materials
and may in turn increase the weight and cost of providing seat belts on
large school buses. However, it is also possible that those putting
seat belt anchorages on large school buses may use existing designs for
small school buses that have always needed to meet the same strength
level that is now being proposed for large school buses.
We request comment on the strength levels being proposed for large
school buses in FMVSS No. 210. Would it be appropriate to reduce the
strength level since the crash environment for large school buses will
likely be less severe than for small school buses? How much could the
load be reduced and still provide an appropriate safety margin in a
variety of crash scenarios? What would be the cost and weight savings
associated with a lesser requirement?
d. Additional Requirements for Large School Buses With Voluntarily-
Installed Lap Belts
New large school buses with voluntarily-installed lap belts would
be required to meet the requirements described in subsection (a) of
this section of the preamble, and the requirements proposed in this
paragraph. This NPRM proposes that seat belt anchorages would have to
meet FMVSS No. 210 requirements of a loading force of 22,240 N (5,000
pounds) per seating position. This would be consistent with the
existing lap belt loading requirement for small school buses and light
vehicles with lap belt only systems.
VII. Quasi-Static Test for Lap/Shoulder Belts on Small and Large School
Buses
The agency has developed a quasi-static test procedure for lap/
shoulder belt-equipped seats in school buses and proposes to apply this
test to small and large school buses equipped with lap/shoulder belts.
The test is intended to address possible safety problems caused by
having both belted and unbelted passengers on the same school bus.
School bus seats designed to provide compartmentalized protection must
contain the child between well-padded seat backs that provide
controlled ride-down in a crash. A school bus seat with a lap/shoulder
belt would have the torso (shoulder) belt attached to the seat back. In
a crash involving a belted child and an unbelted child aft of the
belted occupant, the seat back would be subject to consecutive force
applications from the belted occupant's torso loading the seat back and
the force generated by impact of the unbelted passenger. The quasi-
static test replicates this double-loading scenario and specifies
limits on how far forward the seat back may displace. The test helps
ensure that the top of a seat back does not pull too far forward and
jeopardize the protection of compartmentalized passengers to the rear
of the belted occupants, or diminish the torso restraint effectiveness
for lap/shoulder belted occupants.\26\
---------------------------------------------------------------------------
\26\ A quasi-static test was developed and is being proposed
instead of a dynamic test because school bus manufacturers are
familiar with quasi-static testing. The existing requirements in
FMVSS No. 222 use a quasi-static test (the current
compartmentalization seat performance requirements in S5.1.3) to
assess the capability of the school bus seat to provide protection
in a frontal crash. The agency believes that by using a quasi-static
procedure for testing school bus seats, manufacturers would be able
to test a large number of seats and a variety of design
configurations without incurring the delay and additional cost of
sending each configuration to an outside testing facility.
---------------------------------------------------------------------------
The agency developed the quasi-static test by performing a sled
test using the same large school bus crash pulse that was used in the
school bus research program. We measured the loads on the shoulder
belts and both lower parts of the lap belt. Two unbelted 50th
percentile male dummies were positioned behind the seat that contained
two restrained 50th percentile male dummies. Visual observation of seat
kinematics and load cell data produced by the shoulder belts from this
test revealed the following sequence of events:
1. The knees of the unbelted dummy to the rear struck the back of
the forward seat, causing some seat back deflection.
2. The shoulder belt was loaded by the restrained dummy in the
forward seat.
3. The shoulder belt load was reduced as the seat back to which it
was attached deflected forward.
4. The shoulder belt loads reduced to approximately zero when the
unbelted dummies' chests struck the forward seat back.
5. The forward seat back deflected further forward as the energy
from the unbelted dummies was absorbed.
This crash scenario is replicated in the quasi-static test. The
load requirement for the quasi-static test is dependant upon the number
of seating positions and also the likely seat capacity. A seat that has
the minimal allowed overall seat width for either a two or three
occupant seat will have a reduced loading requirement from other
seats.\27\ The agency is proposing that a 5,000 N (1,124 pounds) load
per occupant be applied in the quasi-static test; however, seats with a
minimal allowed overall seat width would have a 3,300 N (750 pounds)
load per occupant applied.\28\
---------------------------------------------------------------------------
\27\ A school bus bench seat has the minimum allowed overall
width if the total seat width in millimeters minus 380Y is 25 mm (1
inch) or less.
\28\ Based on the assumption of a 5th percentile female occupant
in a seating position as opposed to a 50th percentile male, we
tentatively conclude that the proposed torso body block pull should
be reduced in that situation to 3,300 N (750 pounds) from 5,000 N
(1,124 pounds) or by approximately the same percentage as the ratio
of the mass of a 5th percentile female to that of a 50th percentile
male, i.e., 65 percent [48 kg/74 kg].
---------------------------------------------------------------------------
The reason for the reduced load requirement for the minimal width
seats is that students at the 50th percentile male or larger size would
not be able to simultaneously occupy each of the seating positions. For
example, a 45 inch seat would have a seating capacity of three, or the
minimum allowed overall seat width for a three occupant seat. However,
a common practice used for the seating configuration in large school
buses to be equipped with lap/shoulder belts has been to install a
1,143 mm (45 inches) three position seat on one side of the aisle and a
762 mm (30 inches) two position seat on the other side of the aisle in
each row of the bus. To accommodate students larger than the 5th
percentile female, schools typically seat two persons in the 1,143 mm
(45 inches) seat and one person in the 762 mm (30 inches) seat. Because
the seat width is not sufficient to accommodate the 50th percentile
occupants at the full seating capacity (i.e., three in the 1,143 mm and
two in the 762 mm seats), we are proposing that the quasi-static torso
belt test have a reduced load.\29\
---------------------------------------------------------------------------
\29\ We note that the total loading applied for a 45 inch seat
under this proposal would be 9,900 N (3,300 N x three 5th percentile
occupants) as compared to 10,000 N if it were tested for two 50th
percentile occupants. A 30 inch seat would have a total load of
6,600 N (3,300 N x two 5th percentile occupants) rather than 5,000 N
total load if one 50th percentile occupant were seated in the seat.
---------------------------------------------------------------------------
We believe that if the seat has the minimal allowed overall seat
width it is reasonable to reduce the total torso belt loading applied
to the seat in the quasi-static test to a per occupant value below the
loading applied for larger seating width, since larger occupants would
not occupy those seats to the full seating capacity. To estimate the
appropriate load value, we assume the worst case loading condition is
approached when
[[Page 65522]]
every seating position is occupied by a child as large as a 5th
percentile adult female.\30\
---------------------------------------------------------------------------
\30\ Of course, the seat could be used by occupants of other
sizes and in other combinations. For example, two 50th percentile
male occupants might occupy the outboard seating positions in a
three position, 1,143 mm (45 inch) seat or a 50th percentile male
and a smaller child might occupy a two seating position, 762 mm (30
inch) seat. However, we believe the loading applied by other
occupant combinations will not result in drastically higher loading
applied to the seat through the seat belts.
---------------------------------------------------------------------------
We also believe the proposed loading requirements are practicable.
Testing at NHTSA's Vehicle Research Test Center revealed that existing
lap/shoulder belt equipped seats could meet a torso body block pull of
3,300 N (750 pounds) per occupant.\31\ NHTSA in-vehicle testing at MGA
Research Corporation of three-position, 1,143 mm (45 inches) seats with
lap/shoulder belts in a large school bus, also revealed that these
seats would pass the quasi-static test.\32\
---------------------------------------------------------------------------
\31\ VRTC testing determined that the 1,143 mm (45 inch), three
position seat and a 762 mm (30 inch), two position seat would
collapse during the quasi-static test when a torso body block load
of 5,000 N (1,124 pounds) at each seating position was used.
\32\ Research Testing For FMVSS No. 222, School Bus Passenger
Seating and Crash Protection, Report No. 222R-MGA-2007-001,
September 2006, MGA Research Corporation.
---------------------------------------------------------------------------
For small school buses, this NPRM proposes that a 7,500 N (1,686
pounds) load per occupant be applied in the quasi-static test; however,
seats with a minimal allowed overall seat width would have a 5,000 N
(1,124 pounds) load per occupant applied. As explained in NHTSA's
``Technical Analysis to Support Upgrading the Passenger Crash
Protection in School Buses,'' the torso belt loads are higher than for
large school buses because small school buses experience higher crash
accelerations than large school buses.
a. Stage 1: Torso Belt Anchorage Displacement
This part of the quasi-static test replicates steps 1 and 2 of the
crash scenario above. The proposed procedure uses the knee and top
loading bars that are currently specified in S5.1.3 of FMVSS No. 222
(seat back strength), which replicate a passenger's knee and torso
loading the forward seat back \33\ and the FMVSS No. 210 upper torso
body block.\34\ The test procedure uses the bottom loading bar to
replicate the knee loading by the unbelted rear passengers (based on
W), then specifies a pull test on the shoulder belts at each seating
position in the seat to replicate loading of the shoulder belt by the
belted passengers (based on Y). Under the proposed test procedure, the
large school bus shoulder belts would be pulled using the upper torso
body block specified in Figure 3 of FMVSS No. 210 with a force of 5,000
N (1,124 pounds) at each seating position for large school buses, and a
force of 7,500 N (1,686 pounds) for small school buses.\35\ The
proposed rule (S5.1.6.5.4) includes a very specific procedure for
positioning the torso body block. The torso body block force would be
applied in not less than 5 and not more than 30 seconds. We found that
an applied load of 5,000 N (1,124 pounds) for large school buses was
necessary to replicate the torso belt loading from the sled test and to
get the similar seat response observed from high speed video. This is
slightly higher than twice the highest reading of the shoulder belt
load cell (2,161 N). For small school buses, a higher force is proposed
because the small school bus crash pulse has twice the peak
acceleration of the large school bus, i.e., approximately 25 g.\36\
---------------------------------------------------------------------------
\33\ The current knee loading test procedure requires that
initially a force of 3,114 N (700 pounds) times the number of
seating positions in the test seat (w) be applied to the seat back
within 5 and not more than 30 seconds, and then the force is reduced
to 1,557 N (350 pounds) times w. The knee loading bar is locked in
this position for the remainder of the test. The current top loading
test procedure requires an additional force through the top loading
bar until 452 joules (4,000 inch-pounds) times w of energy is
absorbed by the seat back.
\34\ The agency is considering a rulemaking that would replace
the torso body block in FMVSS No. 210 with an updated force
application device. If the upper torso body block in FMVSS No. 210
is changed, the body block discussed in this quasi-static procedure
proposed today may be changed to the new force application device as
well.
\35\ As discussed earlier in this section, these 5,000 N (1,124
pounds) and 7,500 N (1,686 pounds) values would be reduced depending
on the width of the seat.
\36\ The rational for the load application is explained in the
agency's Technical Analysis.
---------------------------------------------------------------------------
At this mid-point of the quasi-static test when the torso block
force is being applied, NHTSA would measure displacement of the torso
belt anchorages. The criterion for passing this part of the test is
that the torso belt anchorages must not displace forward more than a
specified value. The value is a function of the vertical location of
the anchorage and the angle of the seat back surface that
compartmentalizes the occupants rearward of the seat being tested,
i.e., the posterior surface of the seat back.
Basically, for large school buses, the allowable displacement is
equivalent to the amount of displacement that would result from the
seat back deflecting forward 10 degrees past a vertical plane.\37\ For
large school buses, we propose that [thetas] (theta) in the equation
below be limited to 10 degrees as shown in Figure 9 of the proposed
regulatory text. Thus, the total allowable forward horizontal
displacement for large school buses would be:
---------------------------------------------------------------------------
\37\ The derivation of the equation defining this displacement
limit is explained in the agency's Technical Analysis.
Large School Bus Displacement Limit = (AH + 100)(tan[thetas] + 0.174/
---------------------------------------------------------------------------
cos[thetas]) mm.
For small school buses, the displacement limit would be equivalent
to the amount of displacement resulting from a seat back deflecting
forward 15 degrees past a vertical plane. The displacement limit would
be determined using the equation:
Small School Bus Displacement Limit = (AH + 100)(tan[thetas] + 0.259/
cos[thetas]) mm.
The allowed displacement for small school buses is greater than the
limit for large school buses to account for our concerns about
practicability of small school buses meeting the displacement
criterion.
As noted above, the goal of the torso belt anchorage displacement
criterion is two-fold. The first goal is to assure that the seat back
to which the torso belt is anchored has sufficient strength to restrain
and protect the belted occupant in a frontal crash. The second goal is
to assure that the seat back is still in a sufficiently upright
position to compartmentalize unbelted occupants to the rear. Thus, we
believe that the displacement limit should be narrow, to ensure that
seat backs deviate as little as possible from the initial upright
position.
b. Stage 2: Energy Absorption Capability of the Seat Back
The quasi-static test continues with procedures to replicate steps
3, 4 and 5 of the crash scenario above. After the torso anchorage
displacement is measured, the torso body block load is released.
Immediately after this load is released, forward load is applied to the
seat back through the top loading bar. The seat back must be able to
absorb the same amount of energy per seating position (452 joules
(4,000 in-pounds)) as is required of a seat back under the
compartmentalization requirement. However, for this quasi-static test,
the seat back need not perform such that the top loading bar force must
stay in the force/deflection corridor specified for the
compartmentalization requirement.\38\ This is because the torso body
block load may have generated stresses in the seat frame that exceed
the
[[Page 65523]]
elastic limit of the material and result in residual strain. The seat
back would still need to have the capability to absorb 452 joules of
energy from the unbelted rear occupant, but the manner of absorbing the
energy would not be as controlled as when impacting a seat back that
had not been subjected to the previous loading from the seat belts.
---------------------------------------------------------------------------
\38\ A separate FMVSS No. 222 forward loading test is still
performed on a different test specimen, one that was not subjected
to the quasi-static test, to assure that in a crash, if the seat
were not occupied by a belted passenger and it were impacted by an
unbelted rearward passenger, the seat would meet the force/
deflection corridor.
---------------------------------------------------------------------------
c. Request for Comments
We note that in the above quasi-static procedure, no load
is applied through the pelvis body block. This is because a visual
assessment showed the desired seat response could be achieved with just
the torso body block load. Also, a main focus of the test is to assure
that the top of the seat back does not pull too far forward and
jeopardize the protection of compartmentalized passengers to the rear
of the belted occupants. The agency seeks comment on whether the quasi-
static test should apply a pelvis block loading.
The agency also seeks comment on the proposal to have a
more rigorous quasi-static seat test for small school buses than for
large school buses. We also seek comment on the appropriate level of
the torso block loading to be applied during the test and allowable
anchorage displacement. Would it be appropriate and reasonable to
impose the same displacement limit as is being proposed for large
school buses?
Comments are requested on the validity of the assumption
that the timing of the seat loading is such that the seat belt loading
will essentially be finished before the upper part of the seat back is
loaded by the rear compartmentalized dummy.
The agency also seeks comment on the proposed procedure
(see S5.1.6.5.4 of the proposed rule) for positioning the torso block.
Is the proposed procedure sufficiently clear? Are there ways to improve
the clarity of the test procedure?
VIII. Lead Time
If the proposed changes in this NPRM are made final, NHTSA proposes
a one year lead time for school bus manufacturers to meet the new
minimum seat back height (24 inches), seat cushion test and barrier
requirements for all school buses, since there is limited or no
development necessary for these changes.
We note that lap/shoulder belts are currently available from two
suppliers. We are aware of at least one school bus manufacturer
(Collins) that is already manufacturing its own lap/shoulder belt
seats. We further propose a one year lead time for meeting requirements
for voluntarily installed seat belts in large school buses and a three
year lead time for meeting mandatory installation in small school
buses. We believe three years are necessary for small school buses
since some design, testing, and development will be necessary to
certify compliance to the new requirements. Nothing in this NPRM
proposes to require that large school buses be fitted with seat belt
anchorages, with lap belts, or lap/shoulder belts.
If the proposed changes in this NPRM are made final, NHTSA proposes
that optional early compliance be permitted.
IX. Rulemaking Analyses and Notices
Executive Order 12866 and DOT Regulatory Policies and Procedures
This rulemaking document was not reviewed by the Office of
Management and Budget under E.O. 12866 and is not considered to be
significant under E.O. 12866 or the Department's Regulatory Policies
and Procedures (44 FR 11034; February 26, 1979). NHTSA has prepared a
preliminary regulatory evaluation (PRE) for this NPRM.\39\
---------------------------------------------------------------------------
\39\ NHTSA's preliminary regulatory evaluation (PRE) discusses
issues relating to the potential costs, benefits and other impacts
of this regulatory action. The PRE is available in the docket for
this NPRM and may be obtained by contacting Docket Management at the
address or telephone number provided at the beginning of this
document.
---------------------------------------------------------------------------
This NPRM proposes: (a) For all school buses, to increase seat back
height from 20 inches to 24 inches, and to require a self-latching
mechanism for seat bottom cushions that are designed to flip-up \40\;
and (b) for small school buses (GVWR of 4,536 kg (10,000 lb) or less,
require lap/shoulder belts instead of just lap belts. The belt systems
would be required to meet specifications for retractors, strength,
location and adjustability. Seat backs with lap/shoulder belts would be
subject to a quasi-static test so that the seat backs are strong enough
to withstand the forces from a belted passenger and force imposed on
the seat from unbelted passenger seated behind rear the belted
occupant. This NPRM also proposes: (c) Performance requirements for
voluntarily-installed seat belts on large (over 4,536 kg (10,000 lb))
school buses. For large school buses with voluntarily-installed lap/
shoulder belts, the vehicle would be subject to the requirements
described above for lap/shoulder belts on small school buses, except
that applied test forces and performance limits would be adjusted so as
to be representative of those imposed on large school buses. Large
school buses with voluntarily-installed lap belts would be required to
meet anchorage strength requirements. This NPRM does not require seat
belts to be installed on large school buses. The proposed performance
requirements for seat belts on large school buses affect large school
buses only if purchasers choose to order seat belts on their vehicles.
---------------------------------------------------------------------------
\40\ The agency estimates that a self-latching mechanism on
flip-up seat bottoms would cost less than $3 per seat, or $66 per
bus. This cost was not included in the estimates given below.
Comments are requested on the number of school buses and school bus
seats affected by the seat latching requirement.
---------------------------------------------------------------------------
School Bus Fleet 2007 Fact Book on U.S. school bus sales for the
sales years 2001-2005 reports that for each of these years on average,
approximately 40,000 school buses were sold. NHTSA estimates that of
the 40,000 school buses sold per year, 2,500 of them were 10,000 pounds
GVWR or under. The other 37,500 school buses were over 10,000 pounds
GVWR. Four states currently require high back seats (Illinois, New
Jersey, New York, and Ohio). These states have 21.7 percent of the
sales. Thus, the high back seat incremental costs apply to 78.3 percent
of these sales or 1,958 buses that are 10,000 pounds GVWR or under and
29,362 buses that are over 10,000 pounds GVWR.
Small School Buses
NHTSA estimates that the costs of this rulemaking would be the
incremental cost of the higher (24 inch) seat back ($45 to $64 per
small school bus for 78.3 percent of the fleet) plus the incremental
cost for lap/shoulder belts over lap belts of $1,121 to $2,417. This
would be a total incremental cost per school bus of $1,166 to $2,481
per bus for those states without high back seats. If it is assumed that
in a given year, 2,500 small school buses are sold, for all small
school buses, the total incremental costs of this rulemaking are
estimated to be from $2,889,000 ($45 x 1,958 + $1,121 x 2,500 small
school buses) to $6,167,000 ($64 x 1,958 + $2,417 x 2,500 small school
buses).
The estimated benefits resulting from the higher seat backs and
lap/shoulder belts on small school buses is, per year, 37.2 fewer
injuries, and 0.4 fewer fatalities.
Large School Buses
Costs of Higher Seat Backs on Large School Buses--If this NPRM were
made final, all large school buses would be required to have the higher
seat backs of 24 inches. NHTSA estimates the cost per large school bus
of the higher seat back to be $125. If this NPRM were made final, NHTSA
estimates that the total costs of the higher seat backs on large school
buses to be $3,680,000 (29,362 large school buses times $125.40).
[[Page 65524]]
Benefits of Higher Seat Backs on Large School Buses--If this NPRM
were made final, the benefits from higher seat backs on large should
buses is estimated to be 29.6 fewer injuries per year, and 0.2 fewer
fatalities per year.
Costs and Benefits of Performance Requirements for Voluntarily-
Installed Belts on Large School Buses--As earlier noted, nothing in
this rulemaking would require any party to install lap or lap/shoulder
belts at passenger seating positions in large school buses. Instead,
this rulemaking would specify performance requirements that
voluntarily-installed lap or lap/shoulder belts at passenger seating
positions must meet. Lap or lap/shoulder belts that are now installed
in large school buses would be affected by this rulemaking, in that the
voluntarily-installed belt systems would be subject to the performance
requirements set forth in this NPRM whereas currently the systems are
not subject to any Federal standard. The agency is unable to estimate
the costs and benefits of this part because not enough is known about
the requirements that state and local authorities now specify for the
performance of seat belt systems on large school buses. Comments are
requested on the added costs that would result from the belt systems
having to meet the performance requirements specified in this NPRM.
Overview of Costs and Benefits
Costs of High Back Seats and Lap/Shoulder Belts for Small School Buses,
and of High Back Seats for Large School Buses
Small School Buses: Adding together the high back seat incremental
cost of $45 to $64 to the incremental cost for lap/shoulder belts over
lap belts of $1,121 to $2,417, results in a total incremental cost of
$1,166 to $2,481 per bus.
Large School Buses: The incremental cost for high back seat is
estimated to be $125 per bus.
Table 1.--Total Costs (per bus and for the Fleet)
[$2006]
----------------------------------------------------------------------------------------------------------------
Large buses Small buses Small buses
----------------------------------------------------------------------------------------------------------------
66 passenger........... 14 Passenger........... 20 Passenger.
Per Bus Costs........................ $125................... $1,166................. $2,481.
Annual Fleet Costs................... $3.7 million........... $2.9 million........... $6.2 million.
Combined Annual Fleet Costs...... $6.6 to $9.9 Million...
----------------------------------------------------------------------------------------------------------------
Benefits of High Back Seats and Lap/Shoulder Belts for Small School
Buses, and of High Back Seats for Large School Buses
The benefits of the proposal for small school buses and large
school buses are estimated as shown below in Table 2:
Table 2.--Total Benefits
--------------------------------------------------------------------------------------------------------------------------------------------------------
Small school bus Large school bus Total
--------------------------------------------------------------------------------------------------------------------------------------------------------
Injuries Fatalities Injuries Fatalities Injuries Fatalities
--------------------------------------------------------------------------------------------------------------------------------------------------------
High Back Seat.......................................... Combined below\1\ 30 0.2 30 0.2
--------------------------------
Lap/Shoulder Belts...................................... 37 0.4 n.a. n.a. 37 0.4
Total............................................... 37 0.4 30 0.2 67 0.6
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ We did not have test data to allow us to separate out the high back seats from lap/shoulder belts for small school buses; thus, these data have been
combined.
Regulatory Flexibility Act
Pursuant to the Regulatory Flexibility Act (5 U.S.C. 601 et seq.,
as amended by the Small Business Regulatory Enforcement Fairness Act
(SBREFA) of 1996), whenever an agency is required to publish a notice
of rulemaking for any proposed or final rule, it must prepare and make
available for public comment a regulatory flexibility analysis that
describes the effect of the rule on small entities (i.e., small
businesses, small organizations, and small governmental jurisdictions).
The Small Business Administration's regulations at 13 CFR part 121
define a small business, in part, as a business entity ``which operates
primarily within the United States.'' (13 CFR Sec. 121.105(a)). No
regulatory flexibility analysis is required if the head of an agency
certifies that the rule will not have a significant economic impact on
a substantial number of small entities. The SBREFA amended the
Regulatory Flexibility Act to require Federal agencies to provide a
statement of the factual basis for certifying that a rule will not have
a significant economic impact on a substantial number of small
entities.
NHTSA has considered the effects of this rulemaking action under
the Regulatory Flexibility Act. According to 13 CFR Section 121.201,
the Small Business Administration's size standards regulations used to
define small business concerns, school bus manufacturers would fall
under North American Industry Classification System (NAICS) No. 336111,
Automobile Manufacturing, which has a size standard of 1,000 employees
or fewer. Using the size standard of 1,000 employees or fewer, NHTSA
estimates that there are two small school bus manufacturers in the
United States (U.S. Bus Corp. and Van-Con). NHTSA believes that both
U.S. Bus Corp and Van-Con manufacture small school buses and large
school buses.
[[Page 65525]]
I hereby certify that if made final, this proposed rule would not
have a significant economic impact on a substantial number of small
entities. If this NPRM were made final, the small businesses
manufacturing small buses would incur incremental costs ranging from a
low of $1,166 to $2,481 per small school bus, out of a total cost of
$40,000 to $50,000 per small school bus. The small businesses
manufacturing large school buses would incur incremental costs of $125
per school bus (out of a total of more than $70,000) for the costs of
the higher seat backs. The costs of lap/shoulder belts on large school
buses is not a factor, as nothing in this NPRM would require lap/
shoulder belts or lap belts at passenger seating positions in large
school buses.
The relatively minimal additional costs outlined above for large
and small school buses would be passed on to school bus purchasers.
Those purchasers are required to be sold school buses if they purchase
a new bus, and to use school buses. Thus, small school bus
manufacturers would not lose market share if the changes proposed in
this NPRM were made final. While small organizations and governmental
jurisdictions procuring school buses would be affected by this
rulemaking in that the cost of school buses would increase, the agency
believes the impacts on these entities would not be significant.
Executive Order 13132
NHTSA has examined today's NPRM pursuant to Executive Order 13132
(64 FR 43255, August 10, 1999). On July 11, 2007, NHTSA held a public
meeting bringing together a roundtable of state and local government
policymakers, school bus manufacturers, pupil transportation
associations and consumer groups to discuss the safety, policy and
economic issues related to seat belts on school buses (see NHTSA Docket
28103). No additional consultation with States, local governments or
their representatives is contemplated beyond the rulemaking process.
Further, the agency has concluded that the rulemaking would not have
federalism implications because it would not have ``substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government.'' This
proposal would specify performance requirements for seat belts
voluntarily installed on large school buses, but does not propose to
require the belts on the large buses.
Further, no consultation is needed to discuss the preemptive effect
of today's rulemaking. NHTSA rules can have preemptive effect in at
least two ways. First, the National Traffic and Motor Vehicle Safety
Act contains an express preemptive provision: ``When a motor vehicle
safety standard is in effect under this chapter, a State or a political
subdivision of a State may prescribe or continue in effect a standard
applicable to the same aspect of performance of a motor vehicle or
motor vehicle equipment only if the standard is identical to the
standard prescribed under this chapter.'' 49 U.S.C. 30103(b)(1). It is
this statutory command that preempts State law, not today's rulemaking,
so consultation would be inappropriate.
In addition to the express preemption noted above, the Supreme
Court has also recognized that State requirements imposed on motor
vehicle manufacturers, including sanctions imposed by State tort law,
can stand as an obstacle to the accomplishment and execution of a NHTSA
safety standard. When such a conflict is discerned, the Supremacy
Clause of the Constitution makes their State requirements
unenforceable. See Geier v. American Honda Motor Co., 529 U.S. 861
(2000). NHTSA has not outlined such potential State requirements in
today's rulemaking, however, in part because such conflicts can arise
in varied contexts, but it is conceivable that such a conflict may
become clear through subsequent experience with today's standard and
test regime. NHTSA may opine on such conflicts in the future, if
warranted. See id. at 883-86.
National Environmental Policy Act
NHTSA has analyzed this NPRM for the purposes of the National
Environmental Policy Act. The agency has determined that implementation
of this action would not have any significant impact on the quality of
the human environment.
Paperwork Reduction Act
Under the procedures established by the Paperwork Reduction Act of
1995, a person is not required to respond to a collection of
information by a Federal agency unless the collection displays a valid
OMB control number. This NPRM would not establish any new information
collection requirements.
National Technology Transfer and Advancement Act
Under the National Technology Transfer and Advancement Act of 1995
(NTTAA) (Public Law 104-113), ``all Federal agencies and departments
shall use technical standards that are developed or adopted by
voluntary consensus standards bodies, using such technical standards as
a means to carry out policy objectives or activities determined by the
agencies and departments.'' After carefully reviewing the available
information, NHTSA has determined that there are no voluntary consensus
standards relevant to this rulemaking.
Executive Order 12988
With respect to the review of the promulgation of a new regulation,
section 3(b) of Executive Order 12988, ``Civil Justice Reform'' (61 FR
4729, February 7, 1996) requires that Executive agencies make every
reasonable effort to ensure that the regulation: (1) Clearly specifies
the preemptive effect; (2) clearly specifies the effect on existing
Federal law or regulation; (3) provides a clear legal standard for
affected conduct, while promoting simplification and burden reduction;
(4) clearly specifies the retroactive effect, if any; (5) adequately
defines key terms; and (7) addresses other important issues affecting
clarity and general draftsmanship under any guidelines issued by the
Attorney General. This document is consistent with that requirement.
Pursuant to this Order, NHTSA notes as follows. The preemptive effect
of this proposed rule is discussed above. NHTSA notes further that
there is no requirement that individuals submit a petition for
reconsideration or pursue other administrative proceeding before they
may file suit in court.
Unfunded Mandates Reform Act
The Unfunded Mandates Reform Act of 1995 requires agencies to
prepare a written assessment of the costs, benefits and other effects
of proposed or final rules that include a Federal mandate likely to
result in the expenditure by State, local or tribal governments, in the
aggregate, or by the private sector, of more than $100 million annually
(adjusted for inflation with base year of 1995). This NPRM would not
result in expenditures by State, local or tribal governments, in the
aggregate, or by the private sector in excess of $100 million annually.
Executive Order 13045
Executive Order 13045 (62 FR 19885, April 23, 1997) applies to any
rule that: (1) is determined to be ``economically significant'' as
defined under E.O. 12866, and (2) concerns an environmental, health, or
safety risk that NHTSA has reason to believe may have a
disproportionate effect on children.
[[Page 65526]]
This rulemaking is not subject to the Executive Order because it is not
economically significant as defined in E.O. 12866.
Executive Order 13211
Executive Order 13211 (66 FR 28355, May 18, 2001) applies to any
rulemaking that: (1) Is determined to be economically significant as
defined under E.O. 12866, and is likely to have a significantly adverse
effect on the supply of, distribution of, or use of energy; or (2) that
is designated by the Administrator of the Office of Information and
Regulatory Affairs as a significant energy action. This rulemaking is
not subject to E.O. 13211.
Plain Language
Executive Order 12866 and the President's memorandum of June 1,
1998, require each agency to write all rules in plain language.
Application of the principles of plain language includes consideration
of the following questions:
Have we organized the material to suit the public's needs?
Are the requirements in the rule clearly stated?
Does the rule contain technical language or jargon that
isn't clear?
Would a different format (grouping and order of sections,
use of headings, paragraphing) make the rule easier to understand?
Would more (but shorter) sections be better?
Could we improve clarity by adding tables, lists, or
diagrams?
What else could we do to make the rule easier to
understand?
If you have any responses to these questions, please include them
in your comments on this proposal.
Regulation Identifier Number (RIN)
The Department of Transportation assigns a regulation identifier
number (RIN) to each regulatory action listed in the Unified Agenda of
Federal Regulations. The Regulatory Information Service Center
publishes the Unified Agenda in April and October of each year. You may
use the RIN contained in the heading at the beginning of this document
to find this action in the Unified Agenda.
Privacy Act
Anyone is able to search the electronic form of all comments
received into any of our dockets by the name of the individual
submitting the comment (or signing the comment, 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).
X. Public Participation
How do I prepare and submit comments?
Your comments must be written and in English. To ensure that your
comments are correctly filed in the Docket, please include the docket
number of this document in your comments.
Your comments must not be more than 15 pages long. (49 CFR 553.21).
We established this limit to encourage you to write your primary
comments in a concise fashion. However, you may attach necessary
additional documents to your comments. There is no limit on the length
of the attachments.
Please submit two copies of your comments, including the
attachments, to Docket Management at the address given above under
ADDRESSES.
Comments may also be submitted to the docket electronically by
logging onto the Docket Management System website at http://www.regulations.gov. Follow the online instructions for submitting
comments.
Please note that pursuant to the Data Quality Act, in order for
substantive data to be relied upon and used by the agency, it must meet
the information quality standards set forth in the OMB and DOT Data
Quality Act guidelines. Accordingly, we encourage you to consult the
guidelines in preparing your comments. OMB's guidelines may be accessed
at http://www.whitehouse.gov/omb/fedreg/reproducible.html. DOT's
guidelines may be accessed at MACROBUTTON HtmlResAnchor http://dmses.dot.gov/submit/DataQualityGuidelines.pdf.
How can I be sure that my comments were received?
If you wish Docket Management to notify you upon its receipt of
your comments, enclose a self-addressed, stamped postcard in the
envelope containing your comments. Upon receiving your comments, Docket
Management will return the postcard by mail.
How do I submit confidential business information?
If you wish to submit any information under a claim of
confidentiality, you should submit three copies of your complete
submission, including the information you claim to be confidential
business information, to the Chief Counsel, NHTSA, at the address given
above under FOR FURTHER INFORMATION CONTACT. In addition, you should
submit two copies, from which you have deleted the claimed confidential
business information, to Docket Management at the address given above
under ADDRESSES. When you send a comment containing information claimed
to be confidential business information, you should include a cover
letter setting forth the information specified in our confidential
business information regulation. (49 CFR part 512.)
Will the agency consider late comments?
We will consider all comments that Docket Management receives
before the close of business on the comment closing date indicated
above under DATES. To the extent possible, we will also consider
comments that Docket Management receives after that date. If Docket
Management receives a comment too late for us to consider in developing
a final rule (assuming that one is issued), we will consider that
comment as an informal suggestion for future rulemaking action.
How can I read the comments submitted by other people?
You may read the comments received by Docket Management at the
address given above under ADDRESSES. The hours of the Docket are
indicated above in the same location. You may also see the comments on
the Internet. To read the comments on the Internet, go to http://www.regulations.gov. Follow the online instructions for accessing the
dockets.
Please note that even after the comment closing date, we will
continue to file relevant information in the Docket as it becomes
available. Further, some people may submit late comments. Accordingly,
we recommend that you periodically check the Docket for new material.
Appendix A to the Preamble--Proposed Amendments to Federal Motor
Vehicle Safety Standards
For the convenience of the reader and for illustration purposes,
this appendix generally lists the proposed amendments according to
the affected standard. This NPRM proposes to:
a. Amend 207, Seating Systems, to apply it to school buses with
a GVWR of 4,536 kg (10,000 lb) or less (``small school buses'').
b. Amend FMVSS No. 208, Occupant Crash Protection, to:
1. Require lap/shoulder belt at all passenger-seating positions
on small school buses.
2. Correct a typographical error in the heading of S4.4.5.
3. Specify lockability requirements for seat belts on school
buses.
[[Page 65527]]
c. Amend FMVSS No. 210, Seat Belt Assembly Anchorages, to:
1. Specify a seat belt anchorage strength test of 3,000 pounds
each for the torso and the lap portion of voluntarily-installed lap/
shoulder belt anchorages for passengers in large school buses.
2. Specify a seat belt anchorage strength test of 5,000 pounds
for voluntarily-installed lap belt anchorages in large school buses.
3. Add a requirement concerning lap/shoulder anchorage locations
and adjustability so seat belts on school buses properly fit
passengers from sizes ranging from an average 6-year-old through a
50th percentile adult male.
4. Add a requirement that the seat belts be anchored to the
school bus seat structure.
d. Amend FMVSS No. 222, School Bus Passenger Seating and Crash
Protection, to:
1. Increase seat back height from 20 inches to 24 inches above
the seating reference point, and amend frontal restraining barrier
requirements to make them consistent with the higher seat back
heights.
2. Require lap/shoulder belt restraints instead of the current
lap belts for small school buses.
3. Require voluntarily-installed lap belts and lap/shoulder belt
systems in large school buses to meet performance requirements.
4. Add a quasi-static test for all passenger seats with lap/
shoulder belts, to ensure compatibility between compartmentalization
and lap/shoulder belt systems.
5. Specify a minimum seat belt width of 15 inches for all
passenger school bus seats with lap/shoulder belts.
6. Require all seat bottom cushions that are designed to flip-up
to have a self-latching mechanism.
It is noted that this list does not include FMVSS No. 209,
because that standard already applies to seat belt assemblies for
use in buses, a vehicle class that includes--by definition--school
buses. (See ``school bus'' definition in 49 CFR 571.3.)
List of Subjects in 49 CFR Part 571
Imports, Motor vehicle safety, Motor vehicles, and Tires.
In consideration of the foregoing, NHTSA proposes to amend 49 CFR
Part 571 as set forth below.
PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS
1.The authority citation for Part 571 continues to read as follows:
Authority: 49 U.S.C. 322, 30111, 30115, 30117 and 30166;
delegation of authority at 49 CFR 1.50.
2. Section 571.207 is amended by revising the introductory text of
S4.2, to read as follows:
Sec. 571.207 Standard No. 207; Seating systems.
* * * * *
S4.2. General performance requirements. When tested in accordance
with S5, each occupant seat shall withstand the following forces, in
newtons, except for a side-facing seat, a passenger seat on a bus other
than a school bus, a passenger seat on a school bus with a GVWR greater
than 4,536 kilograms (10,000 pounds), and a passenger seat on a school
bus with a GVWR less than or equal to 4,536 kg manufactured before
[insert compliance date of the final rule].
* * * * *
3. Section 571.208 is amended by revising S4.4.3.3, adding S7.1.5,
and revising the heading of S4.4.5 and S4.4.5.1, to read as follows:
Sec. 571.208 Standard No. 208; Occupant crash protection.
* * * * *
S4.4.3.3 School buses with a gross vehicle weight rating of 4,536
kg (10,000 pounds) or less.
(a) Each school bus with a gross vehicle weight rating of 4,536 kg
(10,000 pounds) or less manufactured before [compliance date to be
inserted] must be equipped with an integral Type 2 seat belt assembly
at the driver's designated seating position and at the right front
passenger's designated seating position (if any), and with a Type 1 or
Type 2 seat belt assembly at all other designated seating positions.
Type 2 seat belt assemblies installed in compliance with this
requirement must comply with Standard No. 209 (49 CFR 571.209) and with
S7.1 and S7.2 of this standard. The lap belt portion of a Type 2 seat
belt assembly installed at the driver's designated seating position and
at the right front passenger's designated seating position (if any)
must meet the requirements specified in S4.4.3.3(c).
(b) Each school bus with a gross vehicle weight rating of 4,536 kg
(10,000 pounds) or less manufactured on or after [compliance date to be
inserted] must be equipped with an integral Type 2 seat belt assembly
at all designated seating positions. The seat belt assembly at the
driver's designated seating position and at the right front passenger's
designated seating position (if any) shall comply with Standard No. 209
(49 CFR 571.209) and with S7.1 and S7.2 of this standard. The lap belt
portion of a Type 2 seat belt assembly installed at the driver's
designated seating position and at the right front passenger's
designated seating position (if any) shall meet the requirements
specified in S4.4.3.3(c). Type 2 seat belt assemblies installed on the
rear seats of school buses must meet the requirements of S7.1.1.5,
S7.1.5 and S7.2 of this standard.
(c) The lap belt portion of a Type 2 seat belt assembly installed
at the driver's designated seating position and at the right front
passenger's designated seating position (if any) shall include either
an emergency locking retractor or an automatic locking retractor, which
retractor shall not retract webbing to the next locking position until
at least \3/4\ inch of webbing has moved into the retractor. In
determining whether an automatic locking retractor complies with this
requirement, the webbing is extended to 75 percent of its length and
the retractor is locked after the initial adjustment. If a Type 2 seat
belt assembly installed in compliance with this requirement
incorporates any webbing tension-relieving device, the vehicle owner's
manual shall include the information specified in S7.4.2(b) of this
standard for the tension-relieving device, and the vehicle shall comply
with S7.4.2(c) of this standard.
* * * * *
S4.4.5 Buses with a GVWR of 10,000 lb (4,536 kg) or less, except
school buses, manufactured on or after September 1, 2007.
S4.4.5.1 Except as provided in S4.4.5.2, S4.4.5.3, S4.4.5.4,
S4.4.5.5 and S4.4.5.6, each bus as with a gross vehicle weight rating
of 10,000 lb (4,536 kg) or less, except school buses, shall be equipped
with a Type 2 seat belt assembly at every designated seating position
other than a side-facing position. Type 2 seat belt assemblies
installed in compliance with this requirement shall conform to Standard
No. 209 (49 CFR 571.209) and with S7.1 and S7.2 of this standard. If a
Type 2 seat belt assembly installed in compliance with this requirement
incorporates a webbing tension relieving device, the vehicle owner's
manual shall include the information specified in S7.3.1(b) of this
standard for the tension relieving device, and the vehicle shall
conform to S7.4.2(c) of this standard. Side-facing designated seating
positions shall be equipped, at the manufacturer's option, with a Type
1 or Type 2 seat belt assembly.
* * * * *
S7.1.5 The seat belt assembly will operate by means of any
emergency-locking or automatic-locking retractor that conforms to 49
CFR 571.209 to restrain persons whose dimensions range from those of an
average 6-year-old child to those of a 50th percentile adult male. The
seat back may be in any position.
* * * * *
4. Section 571.210 is amended by revising S2, amending S3 by adding
definitions for ``school bus torso belt adjusted height'' and ``school
bus torso belt anchor point,'' in alphabetical order, adding S4.1.3,
and S4.1.3.1
[[Page 65528]]
through S4.1.3.5, and adding Figure 4 to the end of the section to read
as follows:
Sec. 571.210 Standard No. 210; Seat belt assembly anchorages.
* * * * *
S2. Application. This standard applies to passenger cars,
multipurpose passenger vehicles, trucks, buses, and school buses.
S3. Definitions.
* * * * *
School bus torso belt adjusted height means the point at which the
torso belt deviates more than 10 degrees from the horizontal plane when
the torso belt is pulled away from the seat by a 20 N force at a
location on the webbing approximately 100 mm from the adjustment device
and the pulled portion of the webbing is held in a horizontal plane.
School bus torso belt anchor point means the midpoint of the torso
belt width where the torso belt first contacts the torso belt
anchorage.
* * * * *
S4.1.3 School bus passenger seats.
S4.1.3.1 Seat belt anchorages on school buses manufactured on or
after [insert compliance date of the final rule] must be attached to
the school bus seat structure and the seat belt shall be Type 1 or Type
2 as defined in S3 of FMVSS No. 209 (49 CFR 571.209).
S4.1.3.2 Type 2 seat belt anchorages on school buses manufactured
on or after [insert compliance date of the final rule] must meet the
location requirements specified in Figure 4. The vertical height of the
school bus torso belt anchor point must be at least 520 mm above the
seating reference point. The school bus torso belt adjusted height must
be adjustable from the torso belt anchor point to within at least 280
mm of the seating reference point.
S4.1.3.3 School buses with a GVWR less than or equal to 4,536 kg
(10,000 pounds) must meet the requirements of S4.1.1 of this standard.
S4.1.3.4 School buses with a GVWR greater than 4,536 kg (10,000
pounds) manufactured on or after [insert compliance date of the final
rule], with Type 1 seat belt anchorages, must meet the strength
requirements specified in S4.2.1 of this standard.
S4.1.3.5 School buses with a GVWR greater than 4,536 kg (10,000
pounds) manufactured on or after [insert compliance date of the final
rule], with Type 2 seat belt anchorages, must meet the strength
requirements specified in S4.2.2 of this standard.
* * * * *
[[Page 65529]]
[GRAPHIC] [TIFF OMITTED] TP21NO07.003
BILLING CODE 4910-59-C
5. Section 571.222 is amended by:
a. Adding to S4, in alphabetical order, a definition of ``seat
bench width''
b. Revising S4.1, paragraphs S5(a) and (b), and paragraph S5.1.2;
c. Redesignating S5.1.5 as S5.1.5(a) and adding paragraph
S5.1.5(b);
d. Adding S5.1.6 and S5.1.7; and revising S5.2.2; and,
e. Adding Figure 8 following Figure 7 at the end of the section.
The revisions and additions read as follows:
Sec. 571.222 Standard No. 222; School bus passenger seating and crash
protection.
* * * * *
S4. Definitions.
* * * * *
Seat bench width means the maximum transverse width of the bench
seat cushion.
* * * * *
S4.1 Determination of the number of seating positions and seat belt
positions
(a) The number of seating positions considered to be in a bench
seat for vehicles manufactured before [insert compliance date here] is
expressed by the symbol W, and calculated as the seat bench width in
millimeters divided by 381 and rounded to the nearest whole number.
(b) The number of seating positions and the number of Type 1 seat
belt
[[Page 65530]]
positions considered to be in a bench seat for vehicles manufactured on
or after [insert compliance date here] is expressed by the symbol W,
and calculated as the seat bench width in millimeters divided by 380
and rounded to the nearest whole number.
(c) The number of seat belt positions in a bench seat equipped with
Type 2 seat belts for vehicles manufactured on or after [insert
compliance date here] is expressed by the symbol Y, and calculated as
the seat bench width in millimeters divided by 380 and rounded to the
next lowest whole number. The minimum seat bench width for a seat
equipped with a Type 2 belt is 380 mm.
* * * * *
S5. Requirements.
(a) Large school buses.
(1) Each school bus manufactured before [insert compliance date]
with a gross vehicle weight rating of more than 4,536 kg (10,000
pounds) shall be capable of meeting any of the requirements set forth
under this heading when tested under the conditions of S6. However, a
particular school bus passenger seat (i.e., a test specimen) in that
weight class need not meet further requirements after having met S5.1.2
and S5.1.5, or having been subjected to either S5.1.3, S5.1.4, or S5.3.
(2) Each school bus manufactured on or after [insert compliance
date] with a gross vehicle weight rating of more than 4,536 kg (10,000
pounds) shall be capable of meeting any of the requirements set forth
under this heading when tested under the conditions of S6 of this
standard or Sec. 571.210. However, a particular school bus passenger
seat (i.e., a test specimen) in that weight class need not meet further
requirements after having met S5.1.2 and S5.1.5, or having been
subjected to either S5.1.3, S5.1.4, S5.1.6 (if applicable), or S5.3.
Each vehicle with voluntarily installed Type 1 seat belts and seat belt
anchorages at W seating positions in a bench seat or Type 2 seat belts
and seat belt anchorages at Y seat belt positions in a bench seat shall
also meet the requirements of:
(i) 4.4.3.3 of Standard No. 208 (49 CFR 571.208);
(ii) Standard No. 209 (49 CFR 571.209), as they apply to school
buses; and
(iii) Standard No. 210 (49 CFR Sec. 571.210) as it applies to
school buses with a gross vehicle weight rating greater than 10,000
pounds.
(b) Small school buses. Each vehicle with a gross vehicle weight
rating of 4,536 kg (10,000 pounds) or less shall be capable of meeting
the following requirements at all rear seating positions:
(1)(i) In the case of vehicles manufactured before September 1,
1991, the requirements of Sec. Sec. 571.208, 571.209, and 571.210 as
they apply to multipurpose passenger vehicles;
(ii) In the case of vehicles manufactured on or after September 1,
1991, the requirements of S4.4.3.3 of Sec. 571.208 and the
requirements of Sec. Sec. 571.209 and 571.210 as they apply to school
buses with a gross vehicle weight rating of 4,536 kg or less;
(iii) In the case of vehicles manufactured on or after [insert
compliance date of the final rule] the requirements of S4.4.3.3(b) of
Sec. 571.208 and the requirements of Sec. Sec. 571.209 and 571.210 as
they apply to school buses with a gross vehicle weight rating of 4,536
kg or less; and
(2) The requirements of S5.1.2, S5.1.3, S5.1.4, S5.1.5, S5.1.6,
S5.3, and S5.4 of this standard. However, the requirements of
Sec. Sec. 571.208 and 571.210 shall be met at Y seat belt positions in
a bench seat, and a particular school bus passenger seat (i.e. a test
specimen) in that weight class need not meet further requirements after
having met S5.1.2 and S5.1.5, or after having been subjected to either
S5.1.3, S5.1.4, S5.1.6, or S5.3 of this standard or Sec. 571.210 or
Sec. 571.225.
* * * * *
S5.1.2 Seat back height, position, and surface area.
(a) For school buses manufactured before [compliance date to be
inserted], each school bus passenger seat must be equipped with a seat
back that has a vertical height of at least 508 mm (20 inches) above
the seating reference point. Each school bus passenger seat must be
equipped with a seat back that, in the front projected view, has front
surface area above the horizontal plane that passes through the seating
reference point, and below the horizontal plane 508 mm (20 inches)
above the seating reference point, of not less than 90 percent of the
seat bench width in millimeters multiplied by 508.
(b) For school buses manufactured on or after [compliance date to
be inserted], each school bus passenger seat must be equipped with a
seat back that has a vertical height of at least 610 mm (24 inches)
above the seating reference point. The minimum total width of the seat
back at 610 mm (24 inches) above the seating reference point shall be
75 percent of the maximum width of the seat bench. Each school bus
passenger seat must be equipped with a seat back that, in the front
projected view, has front surface area above the horizontal plane that
passes through the seating reference point, and below the horizontal
plane 610 mm (24 inches) above the seating reference point, of not less
than 90 percent of the seat bench width in millimeters multiplied by
610.
* * * * *
S5.1.5 Seat cushion retention.
* * * * *
(b) For school buses manufactured on or after [compliance date to
be inserted], school bus passenger seat cushions equipped with
attachment devices that allow for the seat cushion to be removable
without tools or to flip up must have a self-latching mechanism that is
activated when a 22 kg (48.4 pound) mass is placed on the center of the
seat cushion with the seat cushion in the down position.
S5.1.6 Quasi-static test of compartmentalization and Type 2 seat
belt performance.
S5.1.6.1 This section applies to rear passenger seats on school
buses manufactured on or after [compliance date to be inserted] with a
gross vehicle weight rating of more than 4,536 kg (10,000 pounds), and
that are equipped with Type 2 seat belt assemblies. When tested under
the conditions of S5.1.6.5.1 through S5.1.6.5.6, the school bus torso
belt anchor point must not displace horizontally forward more than the
value in millimeters calculated from the following expression:
(AH + 100) (tan[Phi] + 0.174/cos[Phi]) mm
where AH is the height in millimeters of the school bus torso belt
anchor point defined by S4.1.3.2 of FMVSS No. 210 (49 CFR 571.210) and
[Phi] is the angle of the posterior surface of the seat back defined in
S5.1.6.3 of this standard.
S5.1.6.2 This section applies to rear passenger seats on school
buses manufactured on or after [compliance date to be inserted] with a
gross vehicle weight rating less than or equal to 4,536 kg (10,000
pounds), equipped with Type 2 seat belt assemblies. When tested under
the conditions of S5.1.6.5.1 through 5.1.6.5.6, the school bus torso
belt anchor point must not displace horizontally forward more than the
value in millimeters calculated from the following expression:
(AH + 100) (tan[Phi] + 0.259/cos[Phi]) mm
where AH is the height in millimeters of the school bus torso belt
anchor point defined by S4.1.3.2 of FMVSS No. 210 (49 CFR 571.210) and
[Phi] is the angle of the posterior surface of the seat back defined in
S5.1.6.3 of this standard.
S5.1.6.3 Angle of the posterior surface of a seat back. Position
the loading bar specified in S6.5 of this standard so that it is
laterally centered
[[Page 65531]]
behind the seat back with the bar's longitudinal axis in a transverse
plane of the vehicle in a horizontal plane within 6 mm
(0.25 inches) of the horizontal plane passing through the seating
reference point and move the bar forward against the seat back until a
force of 44 N (10 pounds) has been applied. Position a second loading
bar as described in S6.5 of this standard so that it is laterally
centered behind the seat back with the bar's longitudinal axis in a
transverse plane of the vehicle and in the horizontal plane 406 6 mm (16 0.25 inches) above the seating reference
point, and move the bar forward against the seat back until a force of
44 N (10 pounds) has been applied. Determine the angle from vertical of
a line in the longitudinal vehicle plane that passes through the
geometric center of the cross-section of each cylinder, as shown in
Figure 8. That angle is the angle of the posterior surface of the seat
back.
S5.1.6.4 The seat back must absorb 452W joules of energy when
subjected to the force specified in S5.1.6.5.7.
S5.1.6.5 Quasi-static test procedure.
S5.1.6.5.1 If the seat back inclination is adjustable, the seat
back is placed in the manufacturer's normal design riding position. If
such a position is not specified, the seat back is positioned so it is
in the most upright position.
S5.1.6.5.2 Position the lower loading bar specified in S6.5 of this
standard so that it is laterally centered behind the seat back with the
bar's longitudinal axis in a transverse plane of the vehicle and in any
horizontal plane between 102 mm (4 inches) above and 102 mm (4 inches)
below the seating reference point of the school bus passenger seat
behind the test specimen. Position the upper loading bar described in
S6.5 so that it is laterally centered behind the seat back with the
bar's longitudinal axis in a transverse plane of the vehicle and in the
horizontal plane 406 mm (16 inches) above the seating reference point
of the school bus passenger seat behind the test specimen.
S5.1.6.5.3 Apply a force of 3,114W N (700W pounds) horizontally in
the forward direction through the lower loading bar specified at S6.5
at the pivot attachment point. Reach the specified load in not less
than 5 and not more than 30 seconds. No sooner than 1.0 second after
attaining the required force, reduce that force to 1,557W N (350W
pounds) and maintain the pivot point position of the loading bar at the
position where the 1,557W N (350W pounds) is attained until the
completion of S5.1.6.5.5 and S5.1.6.5.6 of this standard.
S5.1.6.5.4 Position the body block specified in Figure 3 of FMVSS
No. 210 (49 CFR 571.210) under each torso belt (between the torso belt
and the seat back) in the passenger seat and apply a preload force of
300 N (67 pounds) on each body block in a forward direction parallel to
the longitudinal centerline of the vehicle pursuant to the
specifications of FMVSS No. 210 (49 CFR 571.210). After preload
application is complete, the origin of the 203 mm body block radius at
any point across the 102 mm body block thickness shall lie within the
zone defined by S5.1.6.5.3(a) through S5.1.6.5.3(c):
(a) At or rearward of a transverse vertical plane of the vehicle
located 100 mm forward of the seating reference point.
(b) At or above a horizontal plane located 195 mm above the seating
reference point.
(c) At or below a horizontal plane located 345 mm above the seating
reference point.
(d) Determination of the seating reference point is provided by the
manufacturer; alternatively, if the seating reference point is not
provided by the manufacturer, NHTSA will make its own determination as
to the seating reference point.
S5.1.6.5.5 (a) For school buses with a gross vehicle weight rating
of 4,536 kg (10,000 pounds) or less, simultaneously apply the following
force to each body block:
(1) If ((seat bench width in mm) - (380Y)) is 25 mm (1 inch) or
less, apply 5,000 N (1,124 pounds); or
(2) If ((seat bench width in mm) - (380Y)) is greater than 25 mm (1
inch), apply 7,500 N (1,686 pounds).
(b) For school buses with a gross vehicle weight rating of greater
than 4,536 kg (10,000 pounds) simultaneously apply the following force
to each body block:
(1) If ((seat bench width in mm) - (380Y)) is 25 mm (1 inch) or
less, apply 3,300 N (742 pounds); or
(2) If ((seat bench width in mm) - (380Y)) is greater than 25 mm (1
inch), apply 5,000 N (1,124 pounds).
S5.1.6.5.6 Reach the specified load in not less than 5 and not more
than 30 seconds. Measure the torso belt anchor point horizontal
displacement and then remove the body block.
S5.1.6.5.7 Apply an additional force horizontally in the forward
direction through the upper bar until 452W joules of energy have been
absorbed in deflecting the seat back. The maximum travel of the pivot
attachment point for the upper loading bar shall not exceed 356 mm as
measured from the position at which the initial application of 44 N of
force is attained. Apply the additional load in not less than 5 seconds
and not more than 30 seconds. Maintain the pivot attachment point at
the maximum forward travel position for not less than 5 seconds, and
not more than 10 seconds and release the load in not less than 5
seconds and not more than 30 seconds. (For the determination of
S5.1.6.5.7, the energy calculation describes only the force applied
through the upper loading bar, and the forward and rearward travel
distance of the upper loading bar pivot attachment point measured from
the position at which the initial application of 44 N of force is
attained.) If energy absorption of 452W joules cannot be obtained by
the seat back, the test procedure is terminated and the seat back is
determined to have failed to meet S5.1.6.4.
S5.1.7 Minimum seat width. For school buses manufactured on or
after [compliance date to be inserted], each passenger seating position
with a Type 2 restraint system shall have a minimum seating width and
seat belt anchor width of 380 mm (15 inches).
* * * * *
S5.2.2 Barrier height, position, and rear surface area. The
position and rear surface area of the restraining barrier shall be such
that, in a front projected view of the bus, each point of the barrier's
perimeter coincides with or lies outside of the perimeter of the
minimum seat back area required by S5.1.2 for the seat immediately
rearward of the restraining barrier.
* * * * *
[[Page 65532]]
[GRAPHIC] [TIFF OMITTED] TP21NO07.004
Issued on: November 15, 2007.
Ronald L. Medford,
Senior Associate Administrator for Vehicle Safety.
[FR Doc. 07-5758 Filed 11-19-07; 10:00 am]
BILLING CODE 4910-59-P