[Federal Register Volume 63, Number 214 (Thursday, November 5, 1998)]
[Rules and Regulations]
[Pages 59732-59741]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-29536]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
[Docket No. NHTSA-98-4662]
RIN 2127-AC19
Federal Motor Vehicle Safety Standards; School Bus Body Joint
Strength
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation.
ACTION: Final rule.
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SUMMARY: This rule amends Federal Motor Vehicle Safety Standard No.
221, School Bus Body Joint Strength (49 CFR 571.221), which requires
school bus body panel joints to be capable of holding the body panel to
the member to which it is joined when subjected to a force of 60
percent of the tensile strength of the weakest joined body panel.
Currently, the standard applies only to school buses with a gross
vehicle weight rating (GVWR) greater than 10,000 pounds. This rule
extends the applicability of the standard to school buses with a GVWR
of 10,000 pounds or less, narrows an exclusion of maintenance access
panels from the requirements of the standard, and revises testing
requirements.
This rule ensures that children are provided equivalent levels of
protection against joint separation in small as well as large school
buses. Since a larger proportion of small school buses than of large
school buses are lift-equipped to transport mobility impaired students
compared to large buses, this rule particularly enhances the safety of
mobility impaired children.
DATES: This rule is effective May 5, 2000. Optional early compliance
with the changes made in this final rule is permitted beginning
November 5, 1998. Any petitions for reconsideration of this final rule
must be received by NHTSA not later than December 21, 1998.
ADDRESSES: Petitions for reconsideration should refer to the docket
number for this action and be submitted to: Administrator, National
Highway Traffic Safety Administration, 400 Seventh Street, SW,
Washington, DC 20590. Copies of the Final Regulatory Evaluation for
this rule can be obtained from: Docket Management, Room PL-401, 400
Seventh Street, SW, Washington, DC, 20590, telephone: (202) 366-9324.
Docket hours are 10 a.m. to 5 p.m., Monday through Friday.
FOR FURTHER INFORMATION CONTACT: Mr. Charles R. Hott, Office of
Crashworthiness Standards, National Highway Traffic Safety
Administration, 400 Seventh Street SW, Washington, DC 20590, (202) 366-
0247.
SUPPLEMENTARY INFORMATION:
I. Summary of the Final Rule
II. Background
II. Amendments
A. Applicability to small school buses
B. Maintenance access panels
C. Other issues relating to exclusions
D. Test procedures
E. Other issues
IV. Rulemaking Analyses and Notices
A. EO 12866; DOT Regulatory Planning and Review and DOT Policies
and Procedures
B. Regulatory Flexibility Act
C. Paperwork Reduction Act
D. National Environmental Policy Act
E. Executive Order 12612 Federalism
F. Civil Justice Reform
I. Summary of the Final Rule
This rule is intended to enhance the applicability and objectivity
of Standard No. 221's school bus joint strength requirements. The
standard currently applies only to large school buses (GVWR greater
than 10,000 pounds). The standard specifies strength requirements for
each ``body panel joint,'' which is currently defined as the area of
contact or close proximity between the edges of a body panel and
another body component, excluding spaces designed for ventilation or
another functional purpose, and excluding doors, windows, and
maintenance access panels (MAPs).
This rule extends the applicability of Standard No. 221 to small
school buses (GVWR of 10,000 pounds or less) and narrows the present
exclusion of MAPs from the joint strength requirements. Except as noted
below, the rule requires panels to be attached at least at every 8
inches (203 millimeters (mm)), and requires body panel joints to
withstand a tensile strength of 60 percent of the tensile strength of
the weakest joined body panel. Excluded from these requirements are
MAPs outside of the passenger area, and MAPs, smaller than a specified
size, inside the passenger area. Joints from which a test sample cannot
be obtained because of the joint's size or the curvature of the panels
comprising the joint, are excluded from the tensile strength
requirements.
Some of the definitions adopted by this rule differ from the NPRM.
For example, the rule simplifies the definition of ``maintenance access
panel,'' and adopts a definition of ``passenger compartment'' based on
the definition in Standard No. 217, Bus Emergency Exits and Window
Retention and Release (49 CFR 571.217). The proposal for deleting the
``hourglass'' shape of the test specimen has not been adopted.
II. Background
NHTSA is authorized by 49 U.S.C. 30101, et seq., to issue Federal
motor vehicle safety standards for new motor vehicles, including school
buses.1 In 1974, Congress enacted the Motor Vehicle and
Schoolbus Safety Amendments (Pub. L. 93-492), which directed NHTSA to
issue Federal motor vehicle safety standards for various aspects of
school bus safety, including interior protection for occupants, floor
strength, and crashworthiness of body and frame. In response to that
Congressional mandate, NHTSA issued Standard No. 221, School Bus Body
Joint Strength.
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\1\ 49 U.S.C. 30125(a)(1) defines a schoolbus as a passenger
motor vehicle designed to carry a driver and more than ten
passengers that the Secretary of Transportation determines ``is
likely to be used significantly to transport preprimary, primary,
and secondary school students to or from school or an event related
to school.'' NHTSA further defines a school bus as a bus that is
sold or introduced in interstate commerce for purposes that include
carrying students to and from school and related events, but does
not include a bus that is designed and sold for operation as a
common carrier in urban transportation. 49 CFR 571.3.
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Standard No. 221 requires the strengthening of school bus body
panel joints to prevent these joints from separating during a crash and
becoming cutting edges that could cause serious injuries or allowing
passenger ejection through openings created by such panel separations.
The standard currently provides that each school bus body panel joint
must be capable of holding the body panel to the member to which it is
joined when subjected to a force of 60 percent of the tensile strength
of the weakest joined body panel. Excluded from this requirement are
doors, windows, spaces designed for ventilation or another functional
purpose, and MAPs. MAPs were excluded because they involve areas on the
vehicle requiring frequent maintenance and need to have unrestricted
accessibility. Although MAPs were not defined in the standard, it was
NHTSA's intent that manufacturers would limit MAPs to panels providing
access to areas requiring routine maintenance.
Maintenance access panels (MAPs). The exception of MAPs from
Standard No. 221 has been an issue of concern to NHTSA, the National
Transportation Safety Board (NTSB), and school bus
[[Page 59733]]
manufacturers. Through information provided by manufacturers and
inspection of buses being built in the years following the effective
date of the standard in 1977, NHTSA learned that most manufacturers
created MAPs that ranged from a few inches up to 12 inches wide above
the window area and extending the entire length of the bus. In
addition, nearly the entire rear wall of some buses was designated as a
MAP.
In testing some of those MAPs after the effective date of the
standard, the agency found the panels to be loosely attached and unable
to withstand much force before detaching from the bus body or adjacent
panels. For example, NHTSA's inspections of a variety of school bus
makes and models disclosed that MAPs extending the length of the bus
above the windows were not fastened down, but were held in place only
by the window frames. On the other hand, NHTSA observed that in some
buses which had been involved in crashes, panels that complied with the
standard performed very well and rarely detached from the bus body and
adjacent panels.
To correct the perceived MAP problem, NHTSA issued a notice of
proposed rulemaking on November 27, 1981 (46 FR 57939) proposing to
remove the exemption for all maintenance access panels except for a few
that were considered critical for proper maintenance.
Over 200 comments were received in response to that notice, all but
two of which opposed the proposed amendments. In addition, public
meetings were held on these issues in March 1982, and again in January
1983. Commenters on the notice and representatives of interested
parties at the meetings contended that NHTSA could show no safety
problem or abuse of the standard and no injuries attributed to MAP
failure, and that extra fasteners could delay proper maintenance
because of difficulties in removing them. They also suggested that the
additional cost of compliance might be $500 per bus with no greater
safety benefits, and that the proposals could include other previously
excluded joints unrelated to MAPs.
NHTSA conducted an internal review of the comments received and
available crash data and concluded that the assertions of the
commenters had substantial merit. The agency was not able to locate a
documented case of personal injury resulting from MAP failure, and was
unable to identify any specific instances of abuse of the MAP
exclusion. The agency believed, however, that the potential for abuse
existed and urged manufacturers to limit their use of MAPs to those
areas where such panels were clearly necessary. The agency also agreed
that requiring extra fasteners on MAPs might not enhance safety because
an increase in fasteners or a decrease in MAPs could complicate the
maintenance process, thus discouraging prompt maintenance. Finally, the
agency concluded that increased compliance costs could be detrimental
to safety by inducing owners of older buses to keep them longer than
they normally would, without a safety benefit. In view of these
considerations, NHTSA terminated the rulemaking on July 2, 1984 (49 FR
27181), but nevertheless urged bus manufacturers to minimize the number
of MAPs.
Although NHTSA terminated the rulemaking, NHTSA continued to
consider the matter in light of additional information received after
the termination, such as documentation of MAP separations in actual
crashes that caused injuries, and evidence that some previously-
complying panels had been redesignated as MAPs. The NTSB, in several
recommendations based on a number of serious school bus accidents
occurring after the termination, proposed elimination of the exclusion
for MAPs and recommended other improvements in school bus safety. The
NTSB also indicated that joint separation had occurred in crashes
involving small school buses.
In June 1987, NHTSA issued an advance notice of proposed rulemaking
(ANPRM) (52 FR 23314; June 19, 1987) on school bus body joint strength
issues. The ANPRM requested comments on possible proposals to specify
minimum strength requirements for the floors of school buses with a
GVWR over 10,000 pounds, narrow the MAP exclusion from the joint
strength requirements of Standard No. 221, and revise the test
procedures of the standard.
Thirty-seven comments were received in response to the ANPRM,
including comments from school bus manufacturers, school bus operators,
and Federal, state and local governmental agencies. After considering
all comments and completing a series of dynamic tests of school bus
floor joints, NHTSA published a notice of proposed rulemaking on March
15, 1991 (56 FR 11142) (hereinafter NPRM), proposing to: (1) Extend the
applicability of Standard 221 to small school buses (GVWR 10,000 pounds
or less); (2) narrow the existing exclusion of MAPs; and (3) expand
testing requirements and clarify testing procedures for school bus body
panel joints.
NHTSA received 18 comments to the NPRM. Commenters included seven
school bus manufacturers, one equipment supplier, six state
organizations, three trade and citizens' associations, and one private
citizen. All comments were fully considered and the significant ones
are addressed below.
III. Amendments
A. Applicability to Small School Buses
This rule extends the applicability of Standard No. 221 to small
school buses (GVWR 10,000 pounds or less), as proposed.
Commenters were divided in their support of NHTSA's proposal to
extend the standard to small school buses. The Maryland State
Department of Education (MSDE), Maryland Motor Vehicle Administration
(MMVA), Washington Superintendent of Public Instruction (SPI),
Connecticut Department of Motor Vehicles (CDMV), California Department
of Education (CDE), and the Blue Bird Body Company (Blue Bird) all
expressed support for the proposal. In general, the state agencies
believed that small school buses should offer the same passenger
protection as large school buses. Blue Bird stated that although there
does not appear to be sufficient safety need or cost benefit
justification for extending the requirements of Standard No. 221 to
small school buses, the company supports the proposal in the interest
of providing uniform safety levels in all school buses and because use
of small school buses is growing.
Commenters opposed to the extension of Standard No. 221 to small
school buses were Collins Industries (Collins), National Truck
Equipment Association on behalf of the Manufacturers Council of Small
School Buses (MCSSB), General Motors Corporation (GM), Ford Motor
Company (Ford), and Mid Bus Inc. (Mid Bus). Most of these commenters
believed that the findings of the NTSB were insufficient to establish a
safety need to extend the standard to small school buses.
The agency disagrees, and believes there is a safety need to extend
the standard to small school buses. NTSB was concerned that small
school buses experience higher crash forces in a crash than do large
school buses, since size and mass are important factors in crash
severity. The NTSB studies on the crashworthiness of large and small
school buses found that 6 of 19 small school bus crashes resulted in
body panel joint separation (32 percent of the cases studied). In
contrast, joint separations in large school buses
[[Page 59734]]
occurred in MAPs and floor joints, while body panel joints maintained
structural integrity very well, even in severe crash forces. These
results indicate that the requirements of Standard 221 are very
effective (see NTSB Safety Study: Crashworthiness of Small Poststandard
School Buses, October 11, 1989). Further, these results lead NHTSA to
conclude that the structural integrity of small buses would be enhanced
by the joint strength requirement of Standard 221. NHTSA concludes that
small school buses should at least be subject to the same joint
strength requirements as large school buses. This will better ensure
that all children are provided equivalent levels of protection against
injuries from joint separation, regardless of the GVWR of the vehicle
transporting them.
Small school buses are becoming an increasingly larger part of the
school bus fleet. From 1988 to 1993, the percentage of total school bus
sales for small school buses rose from about 13 percent to about 19
percent (an increase of almost 50 percent in market share). From 1994
to the present, the percentage of small school bus sales has been
holding steady at about 16 percent. This rise of sales is of concern
because it indicates that crashes, and resultant injuries, are likely
to increase.
Moreover, the agency notes that a larger proportion of small school
buses than of large buses are lift-equipped to transport mobility
impaired students. The school bus industry describes Type A and Type B
school buses as being for ``disability/special purpose'' use. Extending
Standard No. 221's requirements to small school buses thus enhances the
safety of mobility impaired children. In addition, these buses may
frequently be used to carry pre-primary, Head Start program children.
GM stated that small school buses are already subject to standards
not applicable to large school buses, such as Standard Nos. 204, 208,
209, 210, 212, 219, and 301. Therefore, GM argued, a vehicle built in
compliance with those standards has inherent structural integrity and
occupant protection. Collins and MCSSB stated that small school buses
actually have a double approach to passenger protection and restraint
in crashes since they are subject to the compartmentalization
requirements of large school buses as well as the seat belt
requirements of Standard No. 208, Occupant Crash Protection.
NHTSA is not persuaded by these comments. The standards cited by GM
help ensure the crashworthiness of a small school bus, but those
standards address safety systems that are not directly relevant to
school bus body panel joint integrity. For example, Standard No. 204
limits the rearward displacement of the steering control into the
passenger compartment; 208, 209 and 210 address the occupant belt
systems; 212 and 219 pertain to retention and intrusion of the
windshield; and 301 addresses the vehicle's fuel system integrity.
Similarly, in response to Collins and MCSSB, the fact that small school
buses must comply with seat belt requirements and most (but not all) of
the compartmentalization requirements of Standard No. 222 is irrelevant
to the issue of upgrading the integrity of the bus body. The seat belt
and compartmentalization requirements for small school buses help
ensure that the passenger is restrained safely. Standard No. 221
regulates the lap joint construction method used to manufacture school
bus bodies. The joint strength requirements will help ensure that the
environment in which the passenger is restrained does not lose
structural integrity in a crash. NHTSA views the occupant restraint and
compartmentalization requirements of Standards No. 208 and 222 as
complementing the joint strength requirements of Standard No. 221, and
not as requirements that obviate the need for them.
MCSSB argued that the cost to manufacturers of bringing small
school buses into compliance with Standard No. 221 would be
prohibitive, considering the need for complete joint analysis, testing
and certification programs, and possible material and design changes.
Mid Bus estimated that having to comply with Standard No. 221
requirements would increase the cost of a small school bus by $1,982
(1996 dollars).2
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\2\ All costs shown are in terms of 1996 dollars unless
otherwise noted.
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The agency disagrees that the cost impact of the rule on small
school buses is unreasonable. Currently, 21 states and the District of
Columbia already require small school buses to comply with the joint
strength requirements of Standard No. 221 at an additional cost ranging
from $91 to $1,087 per vehicle. NHTSA estimates that the sales-weighted
average increase in the consumer cost of a small school bus to comply
with both the joint strength and the MAP requirements would be $343
(for a more detailed discussion of costs, including the cost impacts of
the rule on large school buses, see the discussion of NHTSA's Final
Regulatory Evaluation in the section on Rulemaking Analyses and
Notices, below). All small school bus manufacturers already produce, at
the purchaser's option, small school buses with body panel joints that
comply with Standard No. 221. NHTSA believes, therefore, that extending
the requirements of the standard to all school buses would not create
an undue burden or expense for small school bus manufacturers since
they are already tooled up for producing complying small school buses.
MCSSB expressed concern that chassis manufacturers would refuse to
certify their chassis, forcing small school bus manufacturers to
certify the chassis themselves or go out of business. Ford and Mid Bus
also alluded to the potential problem of chassis manufacturers refusing
to certify their chassis.
NHTSA does not believe the impacts of this rule on final-stage
manufacturers will be unduly burdensome. As noted above, many states
currently require small school buses to meet the joint strength
requirements of Standard No. 221. Any final-stage school bus
manufacturer producing a vehicle for sale in one of these states is
already taking the necessary steps toward fulfilling its contractual
obligations to meet Standard No. 221. In addition, any final-stage
manufacturer of school buses is also required to meet the
compartmentalization requirements of Standard No. 222, the
crashworthiness requirements of Standard Nos. 204, 208, 209, 210, 212,
219, and 301 (as mentioned by GM, above), as well as the comprehensive
series of FMVSSs that apply to school buses (e.g., Standard No. 217 for
emergency exits and No. 108 for school bus lights). The commenters did
not provide any information to demonstrate that a final-stage
manufacturer, who is capable of fulfilling its present obligation to
certify its vehicles to the extensive school bus safety standards,
would be unable to certify to Standard No. 221. Moreover, Standard No.
221 specifies a relatively simple static-pull test procedure that
manufacturers who choose to perform the test would not find burdensome
to conduct. In contrast, Standards No. 212, 219 and 301 specify dynamic
crash tests, and Standard No. 222 call for force applications and the
calculation of head injury criterion values. NHTSA believes that, given
the present certification responsibilities of final-stage manufacturers
of small school buses and the level of testing necessary to test to
FMVSS No. 221, these manufacturers have the means necessary to certify
their vehicles to Standard No. 221, even in the absence of assurances
from the chassis manufacturer. This assumes that
[[Page 59735]]
the chassis manufacturer would not provide such assurances. The agency
believes that the provision in the rule that excludes joints that can
not be physically accommodated in the tensile testing apparatus from
the 60 percent joint strength requirement will make it easier for more
chassis manufacturers to provide assurances to final-stage
manufacturers that the joints on the incomplete vehicle meets Standard
No. 221.
B. Maintenance Access Panels
NHTSA is defining ``maintenance access panel'' to limit a
manufacturer's latitude to designate panels as MAPs and thus be
excluded from the strength requirements of the standard. Under this
rule, to be excluded from the requirements of Standard No. 221 as a
``maintenance access panel,'' a panel must meet the definition of a
MAP, and must also meet certain criteria.
Definition. The definitions pertaining to maintenance access panels
are the same as those proposed in the NPRM. This rule defines
``maintenance access panel'' as ``a body panel which must be moved or
removed to provide access to one or more serviceable component(s).''
This rule also defines ``serviceable component'' as a part of the bus
which is identified by the body or chassis manufacturer in the owners'
or service manuals as requiring routine maintenance at least once each
year. The definition specifies that ``serviceable component'' includes
pneumatic and hydraulic devices, wiring harnesses, and tubing only at
their attachments.
Criteria to be Excluded. However, the rule differs from the NPRM in
setting criteria that a MAP must meet to be excluded from the
requirements of Standard No. 221. To be excluded, the MAP must either:
(1) Be located forward of the passenger seating area (the MAP must not
lie between a vertical transverse plane located 762 mm (30 inches) in
front of the forwardmost passenger seating reference point and a
vertical transverse plane tangent to the rear interior wall of the bus
at the vehicle's centerline); or (2) be located within the passenger
seating area but have an opening that does not exceed 305 mm (12
inches) when measured across any two points diametrically on opposite
sides of the opening.
In the NPRM, NHTSA proposed that any MAP that exposes the bus
interior to areas below the floor, to the engine compartment or to
compartments adjoining the engine compartment, would not be excluded,
regardless of where in the bus interior the MAP was located. NHTSA also
proposed that MAPs, other than those exposing the interior to areas
below the floor or to the engine compartment or to compartments
adjoining the engine compartment, which were in the passenger seating
area had to meet size limits to be excluded from the joint strength
requirements, ensuring that the MAP is no larger than required to
provide access to the serviceable components the MAP covered. The
proposed size limits provided a two-inch access margin around the
periphery of serviceable components or clusters of components for
handling and tool clearance during installation, replacement,
inspection and adjustment procedures. The average spacing between
components within a cluster of components covered by a single MAP could
not exceed four inches.
Five manufacturers, two associations, and two state organizations
commented on the proposal to narrow the exclusion of MAPs. The SPI and
the California Highway Patrol (CHP) concurred with the proposal to
restrict the size and locations of MAPs. SPI asserted that the present
exclusion compromises the safety and structural integrity of school
buses and that the proposed changes reflect a realistic limitation on
the use of access panels.
Commenting in opposition to the NPRM, Thomas and Mid Bus asserted
that there was not sufficient need shown to restrict MAPs. NHTSA
disagrees. After reviewing both NTSB studies as well as reviewing
recent NTSB school bus crash investigation reports, the agency found 7
out of 80 crashes studied involved MAP separations, causing head
laceration injuries in two of the cases. In 4 of the 20 crashes
involving small school buses, body joint separations occurred,
resulting in one occupant with multiple leg fractures. Further, NHTSA's
own tests have shown that MAP joints are not strong and can and do
separate easily.
Navistar International Transportation Corporation (Navistar),
National School Transportation Association (NSTA), MCSSB, and Blue Bird
expressed concern that restricting MAPs as proposed would make required
maintenance too difficult and time-consuming. They argued that
mechanics would not take the time to replace all the fasteners to
restore body panel joints to the 60 percent joint strength, and that
mechanics would experience more cuts and abrasions because of tighter
working areas. Those conditions could result in improperly accomplished
maintenance, delays in required maintenance, increased failure of
improperly-maintained parts, increased maintenance costs, and increased
injuries because of the smaller sizes of the panels. Thomas, Mid Bus,
and NSTA argued that the size restriction is too stringent. Mid Bus
suggested an alternative restriction, i.e., that the MAP should be no
smaller than 92,903 square millimeters (mm2) or 144 square
inches (in2).
NHTSA can not agree with commenters that the proposed MAP
restrictions will necessarily result in maintenance personnel not
replacing all the fasteners after opening or removal. NHTSA believes
that manufacturers are capable of designing their MAPs in such a manner
as to minimize potential problems. For example, school bus designers
and engineers may be able to redesign their current MAPs to provide
fewer fasteners for mechanics to replace. Nevertheless, NHTSA has
decided that the proposed limitations on MAP size are too restrictive.
Clearance of two inches on a side in servicing components does not
appear to be sufficient. After considering other alternatives for MAP
exclusions, NHTSA has decided to exclude from the joint strength
requirements of Standard No. 221 those maintenance access openings that
do not exceed 305 mm (12 inches) when measured across any two points
diametrically on opposite sides of the opening. That measurement is
independent of the serviceable component's perimeter and location. The
adopted restriction will ensure that MAPs are no larger than needed to
provide access to the serviceable components the MAP covered. The
proposed 102 mm (4 inches) average maximum distance limitation between
components has not been adopted since no such component clusters have
been identified either by NHTSA or by the commenters.
Engine access panels. Thomas and Navistar asserted that because
engines need sometimes daily maintenance, engine covers should be
excluded wherever located. NHTSA believes that most front engine buses
have engine covers that are located outside the defined passenger
compartment area and that maintenance on rear engine buses is routinely
accomplished from the outside. Nevertheless, the agency agrees that
direct and often-recurring engine maintenance should be quickly and
easily accomplished. This includes easy accessibility to the engine
compartment by the driver who may not have an extensive array of tools
available. Accordingly, NHTSA has decided that engine access panels
will be excluded from the requirements of the standard.
MAP floor panels. MAPs that expose the bus interior to areas
located below
[[Page 59736]]
the bus floor or within the engine compartment are excluded from
Standard No. 221's requirements if the MAP meets the restrictions on
either MAP location or size described above. The NPRM did not provide
for conditions whereupon interior MAP floor panels or interior MAPs
leading into the engine compartment could be excluded from Standard No.
221. This was because NHTSA believed these panels should be universally
required to comply with the joint strength requirement since the panels
serve to isolate the bus interior from areas where fire is most likely
to occur, and are an integral part of the vehicle's barrier against
passenger compartment fires. In commenting on the proposal, Blue Bird
asserted that subjecting floor panels to the body panel strength
requirements is an unjustified extension of the standard that would do
little to provide fire protection for the passenger compartment. NSTA
stated that the strength of a joint has little or no relation to its
effectiveness as a firestop.
It was NHTSA's intent in making the proposal to protect passengers
as much as possible from fire entering the passenger compartment
through a separated floor panel, as well as to prevent passengers from
being ejected through a separated floor panel. Even though compliance
with the joint strength requirement may not render a floor panel
fireproof, proper joint strength may prevent the panel from separating.
This would, in turn, help confine a fire to the area outside the
passenger compartment, thereby allowing passengers more time to
evacuate the vehicle. However, NHTSA agrees that there is an
insufficient fire-related reason at this time to require any MAP,
regardless of its location outside the bus occupant space or
insignificant size, to meet the joint strength requirement if it is on
the floor. Thus, the rule excludes MAPs on the floor of the vehicle if
the MAP is forward of the passenger compartment or is of a size small
enough to qualify the MAP for the exclusion.
C. Other Issues Relating to Exclusions
Ventilation. Currently, spaces designed for ventilation are
excluded from the body joint strength requirements, and this rule
continues that exclusion. The NPRM proposed to end the exclusion
because the agency believed that the exclusion is not being utilized
and therefore serves no useful purpose. However, Blue Bird and Thomas
informed NHTSA that that belief is not correct. Blue Bird stated that,
contrary to NHTSA's impression, ventilation panels are used for heater
housings, heater air diffusers, heater ducts, heater hose covers, and
air conditioning ducts and diffusers. Blue Bird argued that all those
components serve important functional purposes, that they enclose no
occupant air space, and are typically supported by panels that are
required to comply with the standard. Blue Bird further asserted that
eliminating this exclusion is not justified from a safety need and
would be overly burdensome in terms of cost and restricted access to
those components by maintenance personnel. Thomas stated that this
revision would result in increased costs from redesign and extra
fastening as well as decreased serviceability for the end user of the
vehicle.
After careful consideration of the comments of Thomas and Blue
Bird, NHTSA is persuaded that the ventilated panel exclusion is being
utilized and that ventilation panels do serve important functional
purposes. Further, due to their size and location, ventilation panels
are not as likely as first thought to cause occupant injuries in an
accident. NHTSA believes that extending the joint strength requirements
to these panels would result in increased costs for redesign and
additional fasteners, as well as decreased serviceability for the end
user, without a commensurate safety benefit. Therefore, ventilation
panels will continue to be excluded from the joint strength
requirements of Standard 221.
Perforated panels. Thomas stated that perforated metal sheets are
widely used in the interior linings of school buses to reduce interior
noise. Thomas stated that the perforations do not extend into the joint
area, making the joints stronger than the perforated portions of the
panels. Thomas asserted, therefore, that the perforated portions could
tear before the joints fail. Thomas suggested that NHTSA evaluate the
safety advantages and disadvantages of the use of perforated headlining
material to determine whether ``special considerations'' should be
given for such material.
NHTSA is aware that perforated material is often used in school bus
ceilings for noise reduction. The agency is unaware of any problems
with perforated panels, such as instances where perforations
contributed to the failure of a joint or where panels separated due to
torn perforations. Nevertheless, the agency will monitor the use of
perforated panels and their performance in school buses to determine
whether there is a safety need to limit or otherwise regulate their
use.
Curved and small joints. This rule excludes from the joint tensile
strength requirement joints from which a test sample cannot be obtained
because of the size of the joint or the curvature of the panels
comprising the joint.
The NPRM proposed a procedure for testing curved joints, such as
those found in roof or ceiling joints. The procedure would have
specified that the test specimen is prepared by selecting a joint
segment where the radius of curvature is at least 508 mm (20 inches).
Thomas suggested a method of testing a curved joint, but stated that in
order to prevent distortion of the test results, the gripping devices
must be able to grip the sample in the same radius as the sample
curvature. To avoid such complex test procedures, Thomas strongly
recommended that NHTSA approve the use of surrogate joints.
NHTSA recognizes that the curved shape of such joints poses
difficulty in obtaining accurate test results. The application of force
on a curved surface would cause the surface to flatten, thus
misrepresenting the actual force loading on the panel. Although NHTSA
believes that it is possible to design and fabricate test fixtures and
procedures capable of testing curved joints, such fixtures would
involve additional certification costs for manufacturers and additional
cost for NHTSA in the agency's compliance testing. Since the agency is
not aware of any data indicating that injuries have been caused
disproportionately by curved joint separation, NHTSA believes that the
potential costs and technical difficulty of testing curved joints more
than outweigh any potential safety benefits. However, the agency will
continue to monitor this issue and initiate rulemaking should curved
joint separation become a safety problem.
Thomas and GM commented on NHTSA's proposals to test small and
complex joints such as those taken from door, window, and other small
or inaccessible body panel joints. GM stated that NHTSA's proposals
regarding the testing of these joints did not fully clarify specimen
preparation procedures for such joints found in passenger vans or van
cutaways. The commenters contended that many of the joints in those
vehicles cannot be tested under either current or proposed testing
procedures. GM suggested that NHTSA further study such types of joints
and either further clarify pertinent test procedures or exclude such
joints from the requirements of Standard 221 as being nontestable.
Thomas asserted that the testing of very short pieces of frame that
would require fittings would violate ASTM test principles. Thomas
further
[[Page 59737]]
argued that tests need not be performed in this manner if NHTSA would
approve the use of surrogate sampling.
NHTSA agrees that complex joints such as those found in body panels
configured to join two or more panels in a single plane in any manner
other than linear, as well as other small joints, cannot feasibly be
tested under either current or proposed testing procedures.
Accordingly, NHTSA has decided that test specimens from joints with
discrete fasteners will be taken from 305 mm (12 inch) segments (203 mm
(8 inches) at the neck) of only flat body panels. Small and complex
joints, as well as trim, decorative parts, floor coverings, and molding
strips will not be tested. The agency has no data indicating that any
injuries have been caused by failure of those small and complex joints
or components, and NHTSA believes that the potential cost of trying to
test them would far outweigh any potential safety benefits.
While curved, small and complex joints are excluded from the
tensile test requirement because they cannot be accommodated on the
test apparatus, they are nevertheless subject to the requirement in
S5.1.1 that no body panel, when joined to another body panel, shall
have an unattached segment at the joint longer than 203 mm (8 inches).
Presumably rivets or other fasteners will be used. This requirement
helps ensure that the joints will maintain their integrity in a crash.
D. Test Procedures
This rule makes a number of revisions to Standard No. 221's test
procedures, including adopting a provision that support members must
remain attached to the specimen during testing; and that the term
``approximately perpendicular'' be deleted from S6.3.2 and replaced by
a provision that the joint be in stress at 90 degrees plus or minus 3
degrees from the joint centerline. The parts of the NPRM proposing
these changes did not engender opposition.
In contrast, the proposal that the existing ``hourglass'' shape of
test specimens be eliminated in favor of straight sides was strongly
opposed by Thomas and Blue Bird. The idea behind the proposal was that
with a simple rectangular shape, more joints could potentially be
tested. However, Thomas stated that a straight-sided test specimen was
contrary to the shape principles set forth in the ASTM sample testing
procedures. Those principles were designed to ``even-out'' the force
distortions induced by the testing device. Blue Bird stated that the
proposal to eliminate the hour glass shape was unacceptable, arguing
that the test specimens need to be wider at the grips than at the joint
section being tested. It said that this width is needed to allow for
proper attachment of the specimen to the test grips and to ensure that
adequate loading can be properly applied to the joint portion of the
specimen.
NHTSA is persuaded by the comments of Thomas and Blue Bird and has
decided to retain the hourglass shape of test specimens. The ASTM
Standards call for the shape of the test specimen to be narrower at the
sample's longitudinal centerline than at the ends of the specimen where
the grips are attached. That shape concentrates the load exerted by the
grips in the center of the specimen rather than at the edges as in the
case of a straight-sided specimen.
Another proposal that generated opposition was the proposed
discontinuance of the deduction of the total area of material removed
for installation of fasteners (i.e., holes drilled for installation of
rivets or screws) in calculating the tensile strength of each joined
component. Thomas asserted that the proposal was not logical because
the removal of material to make the fastener holes does in fact reduce
the cross-sectional area being tested. Further, the commenter said that
the change proposed by NHTSA would have the effect of increasing the
joint strength required to meet the test. Blue Bird alluded to the
NHTSA interpretation letter to that company dated November 28, 1978,
which was the basis for the proposal. In that letter, NHTSA stated that
subtracting the fastener holes was the proper procedure for calculating
the correct area of the sample, but did not explain the basis for that
conclusion. Blue Bird urged that subtracting the fastener holes is the
correct method of calculating the area of the sample.
NHTSA has carefully considered this issue in light of the comments
of Thomas and Blue Bird. It is easier for a sample joint to meet the
standard's tensile strength requirement when the deduction is made for
fastener holes. As previously discussed in this notice, the required
strength of a given joint is based on the tensile strength of the
weakest body panel attached at that joint. If the area for fastener
holes were deducted from the total area of the test specimen when
calculating the strength of the test specimen, the tensile strength of
a sample joint could appear higher than the actual tensile strength of
that joint. As a result, a given joint could meet the 60 percent
tensile requirement of Standard 221 using fewer fasteners than those
that would be necessary if the deduction were not made. In setting the
60 percent tensile requirement, the agency determined that minimum
value met the need for motor vehicle safety. Since deducting for
fastener holes can result in a joint being actually weaker than 60
percent of its weakest member, safety is better served if the deduction
were not made. Accordingly, the letter of interpretation issued by this
agency on November 28, 1978 that provided for the deduction is hereby
rescinded.
E. Other Issues
Relative vs. Minimum Strength
Several comments on NHTSA's ANPRM of June 19, 1987 suggested that
NHTSA replace the present relative body joint strength requirement (60
percent of the tensile strength of the weakest joined body panel) with
an absolute minimum strength requirement. Specifically, Thomas
suggested that the minimum required joint strength for interior body
panels be established at 60 percent of the strength of 22 gauge steel,
with a minimum tensile strength of 3,103 mPa (45,000 psi). For exterior
body panels, Thomas suggested that the requirement be based on 20 gauge
steel. The State of Connecticut suggested that a minimum strength
requirement be based on materials currently used in school buses that
performed favorably relative to those that performed poorly in similar
crashes studied by the NTSB. The National Association of State
Directors of Pupil Transportation suggested that minimum strength
requirements be based on 60 percent of the tensile strength of 18 gauge
steel for exterior panels and 20 gauge steel for interior panels,
regardless of the materials used. Ford suggested that NHTSA include a
minimum strength requirement as an optional alternative to the present
relative strength requirement. NHTSA tentatively determined that the
standard should be amended to establish a minimum strength standard,
but requested comments in the NPRM on the issue.
NHTSA received comments on both sides of this issue. Those favoring
establishment of a minimum strength requirement generally agreed that
all school buses, regardless of size, should be subject to the same
body panel joint strength requirements. Thomas disagreed with the
proposal to base a minimum strength requirement on 18 and 20 gauge
steel, contending that 20 and 22 gauge steel would suffice. Connecticut
agreed with Thomas, but disagreed with Ford's suggestion to make an
absolute strength standard optional. The West Virginia Department
[[Page 59738]]
of Education urged adoption of the recommendation of the National
Standards Committee of the 11th National Conference on School
Transportation which met in May 1990. That committee recommended that
school bus body panels be constructed of prime commercial quality steel
or other metal or material with strength at least equivalent to all-
steel, as certified by the manufacturer. The Maryland Departments of
Education and Motor Vehicles believed it appropriate to establish a
minimum absolute joint strength standard which allows for equivalent
strength materials. SPI and the CDE favored basing an absolute strength
standard on 18 and 20 gauge steel for external and internal body panels
respectively, while the CHP favored a standard governing the minimum
strength for the weaker component of each joint, thus preventing the
manufacturer from deliberately selecting body panel materials of low
tensile strength.
Collins, Blue Bird and MCSSB opposed the proposal to set an
absolute minimum strength standard. Collins asserted that the relative
strength standard makes the most sense, insofar as the joint strength
requirements must be consistent with the parent materials being joined,
the expected loads, the probability of occurrence, and the location of
the joint. Blue Bird argued that the proposal was neither practical nor
objective and stated that some state specifications contain design and
performance standards that require manufacturers to provide specific
gauges and thicknesses of material for most body components. MCSSB
asserted that the relative strength standard is preferable to the
absolute standard in that the relative standard provides greater
flexibility in material usage and methods which will increase strength.
To set an absolute minimum requirement would restrict future
developments.
NHTSA carefully considered the comments on this issue and was
persuaded by the comments of Collins, Blue Bird, and MCSSB that body
panel joint strength should be consistent with the bus manufacturers'
choice of body panel materials. School bus manufacturers currently
utilize many different thicknesses, or gauges, of steel in constructing
their bus bodies, depending on the type and location of the joints.
Thicknesses of panels and structural components range from 0.9
millimeters (0.034 inches) to 16 millimeters (.625 inches). Lastly, a
minimum standard based on steel gauge would force manufacturers to
overdesign their lightly loaded joints, requiring costly new tooling.
Many school bus manufacturers are small business entities. Having to
build to the heaviest loaded joint or the thickest gauge, somewhere
between 18 and 22 gauge steel as suggested by commenters, would result
in increases in vehicle weight, manufacturing costs, and operating
costs with little or no corresponding increases in school bus safety
benefits. Therefore, specifying a minimum absolute strength requirement
by specifying a minimum steel gauge would be design restrictive and
require significant changes in current industry design practices and
procedures.
Some commenters expressed concern that under the relative strength
approach, a manufacturer could deliberately select weak materials, thus
lowering overall joint strength and reduce the number of fasteners
needed for assembly. This has not happened under standard industry
practices, however, and this agency has noted no degradation of safety
attributable to the relative strength requirement. In its Safety Study:
Crashworthiness of Large Poststandard School Buses, March 18, 1987, the
NTSB found that large school buses with body panel joints that complied
with the standard maintained structural integrity very well, even in
severe crashes, thus providing effective protection to school bus
occupants. Accordingly, NHTSA perceives no safety basis for changing
the current relative strength standard in favor of an absolute minimum
standard.
Effective Date
49 U.S.C. 30111(d) provides that a standard may not become
effective before the 180th day or later than one year after the
standard is prescribed, except upon a finding that a longer or shorter
lead time is in the public interest. The NPRM proposed an effective
date of 18 months after date of publication in the Federal Register for
this final rule. None of the commenters addressed that issue.
As pointed out above, many if not all small school bus
manufacturers currently offer, as an option, small school buses with
body panel joints that comply with Standard No. 221 to accommodate
those 21 states and the District of Columbia that require such
compliance. The agency believes, therefore, that at least some of the
tooling needed to comply with the changes mandated by this final rule
is already in place. Nevertheless, some additional tooling may be
required for all small school buses to be produced in compliance with
Standard No. 221. In addition, MAPs in both large and small school
buses may require redesign and testing in order to meet the new
requirements. Accordingly, NHTSA believes that 18 months is sufficient
lead time for manufacturers to accomplish any necessary redesign,
retooling, testing, and marketing strategy to meet the requirements
promulgated by this final rule, and that the 18 month lead time is
therefore in the public interest.
IV. Rulemaking Analyses and Notices
A. Executive Order 12866, Regulatory Planning and Review, and DOT
Regulatory Policies and Procedures
NHTSA has evaluated the impacts of this final rule and has
determined that it is significant within the meaning of the Department
of Transportation's regulatory policies and procedures. This rule was
reviewed under E.O. 12866.
The agency has prepared a Final Regulatory Evaluation (FRE) for
this rulemaking action and has placed a copy of that FRE in the public
docket. A copy of the FRE may be obtained by contacting the
Department's Docket at the address given at the beginning of this
document.
As explained in the FRE, NHTSA estimates that the average consumer
cost per vehicle affected by this final rule will be approximately $221
per large school bus and $343 per small school bus. Those retail price
increases include variable costs, fixed factory overhead, tooling, and
manufacturers' and dealers' profit margins. The difference in cost
between large and small buses arises from the fact that large school
buses, which already comply with the body panel joint strength
standards of Standard 221, have only to bring their MAPs into
compliance. Small school buses, on the other hand, which have
heretofore been excluded from the joint strength requirements of
Standard 221, must bring their body panel joints and their MAPs into
compliance.
Information available to NHTSA indicates that the average combined
total of annual sales of large and small school buses is approximately
35,000 units. Approximately 84 percent of those are large and 16
percent are small.
The estimated costs for small school buses were derived as follows.
As discussed above, 21 states and the District of Columbia currently
require small school buses to comply with the joint strength
requirements of Standard No. 221. Sales within those jurisdictions
represent 35 percent of small school bus sales. NHTSA estimates that
the average cost of bringing body panel joints on 65 percent (@($414)
joint strength upgrade) of the small school buses and MAPs on 100
percent (@($74) MAP redesign) of
[[Page 59739]]
the small school buses into compliance with Standard No. 221 will be
$343 per vehicle. (.65($414)+1.00($74)=$343.) The total annual consumer
cost for implementing the terms of this final rule for small school
buses, therefore, is estimated to be $1,920,800. ($343 x 16% of 35,000
school buses.) These costs are based on optional equipment costs and
may be overstated when required on all vehicles.
As noted above, the agency estimates that the average cost per
large school bus will be $222. Thus, the total annual consumer cost of
limiting the MAP exclusion in large school buses would average
approximately $6,526,800 ($222 x 84% of 35,000 school buses).
The total annual consumer cost to implement the amendments
promulgated by this final rule for both large and small school buses is
estimated to be $8,447,600.
NHTSA believes that this rule will reduce 6 to 46 minor to serious
injuries (AIS 1-3) annually. It is estimated that 5 to 33 AIS 1-3
laceration-type injuries will be reduced on large school buses due to
the narrowing of the MAPs requirements. It is also estimated that the
injury reduction for small school buses will be 0 to 3 AIS 1-3
laceration-type injuries and 1 to 10 AIS-3 fracture-type injuries. The
methodology used to obtain these benefits can be found in the Final
Regulatory Evaluation available in the docket.
B. Regulatory Flexibility Act
NHTSA has also considered the impacts of this final rule under the
Regulatory Flexibility Act. NHTSA's analysis appears in the FRE. Based
on such evaluation, I certify that the amendments will not have a
significant economic impact on a substantial number of small entities.
The Regulatory Flexibility Act of 1980 (Pub. L. 96-354) requires
each agency to evaluate the potential effects of its rules on small
businesses, small organizations, and small governmental jurisdictions.
The small businesses and organizations most likely to be affected by
this final rule are: (1) School bus manufacturers; (2) school bus
dealers and distributors; and (3) public and private school bus
transportation owners and operators.
The Small Business Administration (SBA) defines a bus manufacturer
with less than 500 employees as a small business (13 CFR part 121).
Using that definition, the agency believes that many of the school bus
manufacturers qualify as small businesses. As discussed above, most bus
manufacturers known by NHTSA to build small school buses currently
offer small school buses with complying body panel joints as an option.
The manufacturers produce these vehicles to accommodate the 21 states
and the District of Columbia which require that all school buses comply
with Standard No. 221. NHTSA believes, therefore, that no new
manufacturing techniques or tooling will be required by school bus
manufacturers in order to build school buses that comply with the
requirements of Standard No. 221. Further, costs, as a percentage of
the total school bus manufacturing cost, will not increase
significantly. Thus, any impact on total school bus sales will be
negligible. On balance, the agency anticipates little measurable impact
on school bus manufacturers' revenue levels, profitability, or
employment.
The SBA defines a motor vehicle retailer with less than $11,500,000
in annual receipts as a small business. There are approximately 465
school bus dealers and distributors in the United States. Over the past
6 years (1991-1996), an annual average of approximately 35,000 school
buses were sold, representing an average of 75 buses per dealer. In
order to reach the threshold of $11,500,000 in annual sales receipts,
the average dealer would have to sell a much larger number (270) of
large school buses annually, assuming a cost of $45,280 per unit. Thus,
most school bus dealers are probably small businesses. Because of the
negligible cost impact on manufacturers, the agency also anticipates
little measurable impact on retailers' revenue levels, profitability,
or employment.
School bus operators will probably be the group most affected by
the amendments to Standard No. 221 set forth in this final rule because
of increased school bus purchase prices as discussed above, and
possibly increased maintenance costs. The modest increase in purchase
prices is not expected to influence significantly the demand for new
school bus products. The sales weighted average consumer cost increase
of $222 for large school buses is 0.49 percent of the price of a new 66
passenger school bus with an approximate $45,280 retail purchase price.
For small school buses, the estimated incremental consumer cost of $343
per affected vehicle represents 1.21 percent of the retail price of a
new $28,300 small school bus.
It is difficult to predict what impact the projected retail price
increases discussed above will have on school bus purchases by states
and/or school districts. There is a strong and continuing demand for
school buses to transport school children and no alternative to the
purchase of those vehicles. On the one hand, for many states and school
districts operating on tight budgets, a 1.21 percent rise in the prices
of small school buses and a 0.49 percent increase in the prices of
large school buses may result in a proportionate reduction in new
school bus sales. On the other hand, school districts may offset price
increases by purchasing school buses with less optional equipment, such
as luggage racks, extra batteries, or upgraded interiors. Even assuming
the ``tight budget'' scenario, the agency believes that new school bus
sales revenues will remain relatively constant. Thus, the net impact on
school bus production and sales should be negligible.
C. Paperwork Reduction Act
In accordance with the Paperwork Reduction Act (44 U.S.C. 3501 et
seq.), the agency notes that there are no collection of information
requirements associated with this final rule.
D. National Environmental Policy Act
NHTSA has analyzed this final rule for the purposes of the National
Environmental Policy Act. The agency has determined that implementation
of this action will not have any significant impact on the quality of
the human environment.
E. Executive Order 12612, Federalism
NHTSA has analyzed this final rule in accordance with the
principles and criteria contained in Executive Order 12612, Federalism,
and has determined that this final rule has borderline federalism
implications. The agency's initial determination, however, is that such
implications are not sufficient to warrant preparation of a Federalism
Assessment.
F. Civil Justice Reform
This final rule does not have any retroactive effect. Under 49
U.S.C. 30103(b), whenever a Federal motor vehicle safety standard is in
effect, a state or political subdivision may prescribe or continue in
effect a standard applicable to the same aspect of performance of a
motor vehicle only if the standard is identical to the Federal
standard. However, the United States Government, a state or political
subdivision of a state may prescribe a standard for a motor vehicle or
motor vehicle equipment obtained for its own use that imposes a higher
performance requirement than that required by the Federal standard. 49
U.S.C. 30161 sets forth a procedure for judicial review of final rules
establishing, amending or revoking Federal motor vehicle safety
standards. A petition for reconsideration
[[Page 59740]]
or other administrative proceedings is not required before parties may
file suit in court.
List of Subjects in 49 CFR Part 571
Motor vehicle safety, Reporting and recordkeeping requirements,
Tires.
In consideration of the foregoing, 49 CFR 571.221 is amended as
follows:
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;
delegations of authority at 49 CFR 1.50.
2. Standard No. 221 is amended by revising S3; revising the
definitions of ``body panel joint'' and ``bus body'' in S4; adding, in
alphabetical order, the definitions of ``maintenance access panel,''
``passenger compartment'' and ``serviceable component'' to S4; and
revising S5 and S6, to read as follows:
Sec. 571.221 Standard No. 221, School Bus Body Joint Strength.
* * * * *
S3. Application. This standard applies to school buses.
S4. Definitions.
* * * * *
Body panel joint means the area of contact or close proximity
between the edges of a body panel and another body component, including
but not limited to floor panels, and body panels made of composite
materials such as plastic or plywood.
Bus body means that portion of a bus that encloses the bus occupant
space, including the floor and firewall (the body panel separating the
engine compartment from the occupant space), but excluding the bumpers
and chassis frame and any structure forward of the forwardmost point of
the windshield mounting.
* * * * *
Maintenance access panel means a body panel which must be moved or
removed to provide access to one or more serviceable component(s).
Passenger compartment means space within the school bus interior
that is between a vertical transverse plane located 762 mm in front of
the forwardmost passenger seating reference point and including a
vertical transverse plane tangent to the rear interior wall of the bus
at the vehicle centerline.
Serviceable component means any part of the bus, of either a
mechanical or electrical nature, which is explicitly identified by the
bus chassis and/or body manufacturer in the owner's manual or factory
service manual as requiring routine maintenance actions at intervals of
one year or less. Tubing, wires and harnesses are considered to be
serviceable components only at their attachments.
S5. Requirements.
S5.1 Except as provided in S5.2, each body panel joint shall meet
S5.1.1 and S5.1.2.
S5.1.1 Body panels attached to each other shall have no unattached
segment at the joint longer than 203 mm.
S5.1.2 When tested in accordance with the procedure of S6, each
body panel joint shall hold each body panel to the component to which
it is joined when subjected to a force that equates to 60 percent of
the tensile strength of the weakest joined body panel, determined
pursuant to S6.2.
S5.2 Exclusions.
S5.2.1 The requirements of S5.1.1 and S5.1.2 do not apply to--
(a) Any interior maintenance access panel which lies forward of the
passenger compartment, or, which exceeds 305 mm when measured across
any two points diametrically on opposite sides of the opening.
(b) Trim and decorative parts which do not contribute to the
strength of the joint, support members such as rub rails which are
entirely outside of body panels, doors and windows, ventilation panels,
and engine access covers.
S5.2.2 The requirements of S5.1.2 do not apply to joints from
which a test specimen of the dimensions specified in Figure 1 can not
be obtained.
S6 Procedure.
S6.1 Preparation of the test specimen.
S6.1.1 If a body panel joint is 203 mm long or longer, cut a test
specimen that consists of any 203 mm segment of the joint, together
with a portion of the bus body whose dimensions are those specified in
Figure 1, so that the specimen's centerline is perpendicular to the
joint at the midpoint of the joint segment. Where the body panel joint
is not fastened continuously, select the segment so that it does not
bisect a spot weld or a discrete fastener. Support members which
contribute to the strength of a body panel joint, such as rub rails on
the outside of body panels or underlying structure attached to joint
members, shall remain attached to the test specimen, except that
material may be removed from the support members as necessary to clear
the gripping areas of the joint members being tested.
S6.1.2 [Reserved]
S6.1.3 Prepare the test specimen in accordance with the
preparation procedures specified in the 1989 edition of the Annual Book
of American Society for Testing and Materials (ASTM) Standards.
S6.2 Determination of minimum allowable strength. For purposes of
determining the minimum allowable joint strength, determine the tensile
strengths of the joined body components as follows:
(a) If the mechanical properties of a joint component material are
specified by the ASTM in the 1989 Annual Book of ASTM Standards, the
lowest value of that material's tensile strength per unit of area shown
in that source shall be used.
(b) If the mechanical properties of a material are not specified by
the ASTM in the 1989 Annual Book of ASTM Standards, determine its
tensile strength by cutting a sheet specimen from outside the joint
region of the bus body in accordance with Figure 1 of E 8-89 Standard
Test Methods of Tension Testing of Metallic Materials, in Volume 03.01
of the 1989 Annual Book of ASTM Standards, and by testing it in
accordance with S6.3.
(c) The cross sectional area of material removed to facilitate the
installation of fasteners shall be used in the determination of the
tensile strength of the weakest joined body panel.
S6.3 Strength test.
S6.3.1 The joint specimen is gripped on opposite sides of the
joint in a tension testing machine in accordance with the 1989 Annual
Book of ASTM Standards.
S6.3.2 Adjust the testing machine grips so that the applied force
on the joint is at 90 degrees plus or minus 3 degrees from the joint
centerline, as shown in Figure 1.
S6.3.3 A tensile force is applied to the specimen by separating
the heads of the testing machine at any uniform rate not less than 3 mm
and not more than 10 mm per minute until the specimen separates.
3. Figure 1 is revised to read as follows:
BILLING CODE 4910-59-P
[[Page 59741]]
[GRAPHIC] [TIFF OMITTED] TR05NO98.000
BILLING CODE 4910-59-C
Issued: October 29, 1998.
Ricardo Martinez,
Administrator.
[FR Doc. 98-29536 Filed 11-4-98; 8:45 am]
BILLING CODE 4910-59-P
