[Federal Register Volume 64, Number 80 (Tuesday, April 27, 1999)]
[Rules and Regulations]
[Pages 22567-22579]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-10316]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
[Docket No. NHTSA-99-5572; Notice 3]
RIN 2127-AF40
Federal Motor Vehicle Safety Standards; Roof Crush Resistance
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation.
ACTION: Final rule.
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SUMMARY: This document revises the test procedure in Standard No. 216,
Roof Crush Resistance, to make it more suitable to testing vehicles
with rounded roofs or vehicles with raised roofs. The test procedure is
intended to test the strength of the roof over the front seat occupants
by forcing a large flat steel test plate down onto the roof, simulating
contact with the ground in rollover crashes. However, when the
procedure is followed in testing certain vehicles with rounded roofs
(e.g., the Ford Taurus), the test plate is positioned too far back and
does not test the roof over the front occupants. In addition, that
positioning creates the potential for contact between the front edge of
the test plate and the roof. Such contact is undesirable because the
front edge can penetrate the roof structure in a way that the ground
cannot during rollover crashes. Similarly, for vehicles with raised,
irregularly shaped roofs (such as some vans with roof conversions), the
initial contact point on the roof may not be above the front occupants,
but on the raised rear portion of the roof, behind those occupants. In
both of these cases, the positioning of the plate relative to the
initial contact point on the roof, instead of a fixed location on the
roof, results in too much variability in the plate positioning and
reduces test repeatability.
This final rule addresses the problem of rounded roofs by
specifying that, for all vehicles except those with certain modified
roof configurations, the test plate is to be positioned so that the
front edge of the plate is 254 mm (10 inches) in front of the
forwardmost point of the roof. Positioned in this way, the front edge
of the plate will always project slightly forward of the roof instead
of contacting it. Further, the plate will always be positioned over the
front occupants. The rule addresses the problem for vehicles with
raised or modified roofs by specifying that if following the normal
test procedure results in an initial point of contact that is rearward
of the front seats, the rear edge of the plate is positioned just to
the rear of those seats. The rule also makes minor clarifications and
non-substantive changes to the regulatory text.
DATES: The amendments made by this rule are effective on October 25,
1999. The mandatory compliance date is also October 25, 1999, however,
voluntary compliance with this rule is allowed as of April 27, 1999.
Petitions for reconsideration of this rule must be received no later
than June 11, 1999.
ADDRESSES: Petitions for reconsideration should mention the docket
number at the top of this final rule, and be submitted in writing to:
Administrator, National Highway Traffic Safety Administration, Room
5220, 400 Seventh Street, SW, Washington DC, 20590.
FOR FURTHER INFORMATION CONTACT: For non-legal issues, you may call
Maurice Hicks of the Office of Crashworthiness Standards, at telephone
(202) 366-6345, facsimile (202) 366-4329, electronic mail
[email protected].
For legal issues, you may call Paul Atelsek of the Office of the
Chief Counsel, at (202-366-2992), facsimile (202) 366-3820, e-mail:
[email protected]
You may send mail to both of these officials at National Highway
Traffic Safety Administration, 400 Seventh St., S.W., Washington, D.C.
20590.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Background
II. Petitions for rulemaking to amend Standard No. 216
A. Recreation Vehicle Industry Association (RVIA) petition
[[Page 22568]]
B. Ford petition
III. Notice of Proposed Rulemaking (NPRM)
IV. Comments in response to the NPRM
A. Change in the location of the test plate to accommodate
rounded roofs (e.g., Ford Taurus)
B. Altered or raised roofs (e.g., van conversions)
C. Other issues
1. Real world rollover crashes versus Standard No. 216
2. Variability in Standard No. 216 testing
3. Responses to agency questions in the NPRM
V. Agency discussion of issues
A. Summary of changes from the NPRM
B. Plate position for sloped and contoured roofs
C. Use of a small test plate for vehicles with raised or
modified roofs
D. Other issues and concerns
1. Real world rollover crashes versus Standard No. 216
2. Test variability in Standard No. 216 testing
3. Analysis of responses to agency questions in the NPRM
VI. Changes to the regulatory text
VII. Lead time
VIII. Rulemaking analyses and notices
A. Executive Order 12866 and DOT Regulatory Policies and
Procedures
B. Regulatory Flexibility Act
C. Paperwork Reduction Act
D. Executive Order 12612 (Federalism)
E. Civil Justice Reform
I. Background
Federal Motor Vehicle Safety Standard No. 216, Roof Crush
Resistance, is intended to assure that passenger cars, multipurpose
passenger vehicles, and trucks with gross vehicle weight ratings of
less than 10,000 pounds have sufficient structural strength in the roof
over the front seat occupants to resist crushing during rollover
crashes. The test procedure is designed to test the A-pillar and the
roof over the front occupants.
Under the test procedure, the vehicle is secured on a rigid
horizontal surface and placing a 762 mm (30 inches) wide by 1,829 mm
(72 inches) long test plate over the roof. The test plate is oriented
with its 1,829 mm dimension parallel to the longitudinal vertical plane
through the longitudinal centerline of the vehicle, and tilted forward
at a five degree angle. Its 762 mm dimension is tilted outward on its
longitudinal axis at a 25 degree angle so that its outboard side is
lower than its inboard side. So oriented, the test plate is lowered
until it initially contacts the roof. After the initial contact point
on the roof is determined, the test plate is moved, maintaining its
angles and its orientation parallel to the vehicle's longitudinal
centerline, so that the initial contact point touches the underside of
the test plate along the test plate's longitudinal centerline, 254 mm
(10 inches) rearward of the centerline's forwardmost point. The test
plate is then pushed downward in the direction perpendicular to its
lower surface until a load of 1.5 times the unloaded vehicle weight (up
to a maximum of 22,240 N, or 5,000 pounds, for a passenger car) has
been applied. The vehicle complies if its roof prevents the test plate
from moving downward more than 127 mm (5 inches).
Although, as noted above, the intent underlying this test procedure
is to load the area at the top of the A-pillar and the roof over the
front seat area, positioning the test plate according to the procedures
on certain roof configurations may result in testing areas of the roof
to the rear of the front seat area. Ford and the Recreation Vehicle
Industry Association petitioned the agency to modify the test procedure
to solve this problem.
II. Petitions for Rulemaking To Amend Standard No. 216
A. Recreation Vehicle Industry Association (RVIA) Petition
RVIA, a national trade association that reportedly represents more
than 95 percent of the conversion vehicle manufacturers who modify
vans, pickup trucks, and sport utility vehicles, is concerned that
contoured or raised roof structures on certain second stage van
conversions cannot be tested using the current test procedure. The
initial contact point, which for conventional roof structures is
generally near the front edge of the roof at the top of the A-pillar,
is supposed to result in the forward edge of the test plate being
positioned approximately 254 mm (10 inches) in front of the roof.
However, with only a five degree incline of the test plate, the plate
initially contacts some vehicles with raised roofs on the portion of
the raised roof well behind the A-pillar and the front seat area. This
results in testing the raised roof structure instead of the A-pillar
over the front seats.
To address this situation, RVIA petitioned NHTSA to allow vans,
motor homes and other multipurpose passenger vehicles, trucks, and
buses that have raised roofs, to be tested in accordance with the test
procedures in Standard No. 220, School Bus Rollover Protection.
Standard No. 220 specifies the use of a test plate that is larger and
horizontal, and thus distributes the same load evenly over the entire
surface of the roof and all its supporting pillars, rather than
concentrating the load on either side of the roof over the front seats.
In making this request, RVIA reasoned first that, since the raised
roof vehicles would have met Standard No. 216 requirements prior to
modification of their roofs, the A-Pillar strength has already been
demonstrated. Second, RVIA claimed that the modifications usually do
not affect the roof strength near the A-pillar. RVIA believes that the
Standard No. 220 test procedure could be used to test the strength of
the entire modified vehicle roof, without repeating the Standard No.
216 certification test.
B. Ford Petition
Ford is concerned that following the current test procedures in
testing certain vehicles with rounded roof designs (e.g., Ford Taurus,
Dodge Neon) results in initial plate contact so far back on the roof
that the front edge of the test plate is several inches behind the A-
pillar when it is positioned as specified in the Standard. This occurs
because the roofs slope longitudinally at an angle greater than 5
degrees at their front edge. Consequently, the roofs are loaded
somewhere far behind the A-pillar, and roof penetration by the front
edge of the plate can occur.
In addition, Ford states that the current test procedure makes
repeatable testing difficult on these vehicles. The initial contact
point is highly variable and dependent on the specific roof design. The
initial contact point can move several inches forward or rearward if
the plate angle or the level of the floor on which the test vehicle is
placed are off by as little as one degree. This could lead to
substantial differences in test results.
Ford believes that the test procedures as applied to some vehicles
are contradictory. S6.2 of the standard says to ``[o]rient the test
device as shown in Figure 1 * * *'', which shows the test plate in
contact with the front corner of the roof, inclined longitudinally at
an angle of 5 degrees. At the same time, S6.2(d) of the rule specifies
that the initial contact point be 254 mm (10 inches) from the front
edge of the test plate. Since the initial contact point will not be
located at the front corner of the roof for certain vehicles with
rounded roofs, there is a conflict between the specifications in
S6.2(d) and Figure 1 in the regulatory text.
Ford petitioned NHTSA to amend Standard No. 216 to specify that the
front edge of the test plate should always be one inch forward of the
front edge of the roof, measured from the rearmost point of the
windshield. To accomplish this, Ford suggested the following language
to replace S6.2(d):
The initial contact point, or center of the initial contact
area, is on the longitudinal
[[Page 22569]]
centerline of the device. A plane perpendicular to the lower surface
of the test device and 25 mm rearward of the front edge of the lower
surface passes through the rearmost point of the opening in the body
structure for the windshield.
Ford also petitioned NHTSA to amend the test procedure to specify
that all vehicles be tested with the body sills, rather than the
chassis, mounted on the rigid surface, and that all roof rack
components that could interfere with initial contact between the test
plate and the roof be removed prior to testing.
NHTSA granted the two petitions and published a Request for
Comments on December 27, 1994. The responses to the requests for
comments are not discussed here, because they were summarized and
addressed in the subsequent Notice of Proposed Rulemaking (NPRM). This
NPRM is discussed below.
III. Notice of Proposed Rulemaking (NPRM)
On February 27, 1997, NHTSA published an NPRM to amend Standard No.
216 in response to the petitions from Ford and RVIA (62 FR 8906). In
the NPRM, NHTSA proposed to modify the test plate size and placement to
ensure that vehicles with raised and sloped roofs could be tested in
accordance with the intent of the standard.
In response to Ford's petition, the agency proposed modifying the
test plate location to resolve test complications for those vehicles
with highly rounded roofs (e.g., Ford Taurus). It proposed to modify
S6.2(d) to position the forwardmost edge of the test plate flush with
the forwardmost point of the roof structure including the windshield
trim. This, it was thought, would provide for the consistent placement
of the plate and in most cases would properly stress the roof over the
A-pillar junction, while providing a technique that could be used to
test all vehicles. This position was thought to be preferable to Ford's
alternative (25 mm in front of the rearmost point of the windshield
opening), because a vehicle whose window openings are more than 25 mm
farther forward in the center than they are near the A-pillars could
have resulted in the front edge of the plate penetrating the sheet
metal of the roof. In addition, a vehicle whose window openings are
more than 25 mm farther rearward in the center than they are near the
A-pillars can result in a plate forward edge penetration of the sheet
metal behind the A-pillar. This condition, known as ``edge loading,''
is undesirable because it concentrates the load in a very small area
and does not simulate contact with the ground in most rollover crashes.
For vehicles with raised or altered roofs, such as van conversions,
NHTSA denied the portion of RVIA's petition that requested using the
requirements of Standard No. 220 instead of the requirements of
Standard No. 216. Agency testing using both procedures on vehicles with
similar modified/raised roofs showed that the Standard No. 220 test
procedure was less stringent in testing the roof over the front
occupants. Also, since Standard No. 216 specifies that the load is
applied over a smaller contact area (one side of the roof), it would
likely result in roof designs that could withstand a higher load on
that portion of the roof structure.
NHTSA also rejected RVIA's contention that, since roofs of the
original vehicles prior to conversion had already been certified to
Standard No. 216 requirements, the front of the converted roof
structure would have met the requirements of that standard. While the
roofs of original pre-conversion vans are certified, it is unknown how
much the roof strength would have changed when a portion of the roof is
cut out for roof conversions. Therefore, the agency proposed to
continue applying requirements of Standard No. 216.
The NPRM proposed to address RVIA's concerns by decreasing the size
of the test plate in certain situations, depending upon the position of
the initial contact point relative to the front seat area. The size of
the plate would have been determined by positioning the current large
test plate with its lower surface on the roof structure. If the initial
contact point were on any portion of the raised/altered roof section
rearward of the front seat area, then NHTSA proposed to substitute a
small test plate (610 mm by 610 mm, or 24 inches by 24 inches) to be
used for testing instead. The rear of the front seat area was defined
as ``the transverse vertical plane passing through a point 162 mm
rearward of the SgRP of the designated left front outboard seating
position.'' (SgRP stands for seating reference point, as defined in 49
CFR 571.3). The transverse vertical plane 162 mm behind the seating
reference point is where the head of a 50th percentile male Hybrid III
dummy is closest to the roof when the dummy is positioned as specified
in the test procedures for Standard No. 201, Occupant Protection in
Interior Impact. The performance requirements when using the small
plate would be the same as when tested with large plate, i.e., a roof
crush deformation of 127 mm (or 5 inches) at a load of 1.5 times the
unloaded weight of the vehicle.
NHTSA also proposed to make certain minor changes to the regulatory
text, renumbering paragraphs and making minor clarifying changes. In
particular, the NPRM proposed to add to the regulatory language of the
standard the substance of an already issued interpretation, explicitly
stating that the agency would test vehicles with their roof racks and
non-structural components removed. In addition, NHTSA posed a number of
questions to commenters regarding the appropriateness of the standard,
as modified by the proposal.
IV. Comments in Response to the NPRM
In response to the NPRM the agency received a total of 10 comments,
6 comments from manufacturers (GM, RVIA, Volkswagen, BMW and 2
submissions from Ford), one from a safety group (Advocates for Highway
and Auto Safety, or Advocates), one from a state organization
(Minnesota Department of Transportation), one from a research group
(Liability Research Group, or LRG), and one from a law firm (Ricci,
Hubbard, Leopold and Franklin, or RHLF).
A. Change in the Location of the Test Plate To Accommodate Rounded
Roofs (e.g., Ford Taurus)
In response to the proposal to align the front edge of the test
plate with the front edge of the roof, the agency received comments
from GM, Volkswagen, BMW, Ford, and Advocates. GM, Volkswagen, and Ford
supported adopting a fixed location for the test plate near the front
edge of the roof, while BMW supported allowing the position of the test
plate to vary by up to 254 mm relative to a fixed location on the roof.
There was no clear agreement on plate positioning, but most of the
commenters shared concerns about edge loading of the roof or the A-
pillar when testing according to the proposed procedure.
The manufacturers each favored a different position for the front
edge of the plate. GM recommended that the test plate be located 50 mm
(2 inches) forward from the forwardmost point on the ``top edge of the
windshield.'' Volkswagen suggested the front edge of the plate be
placed 25 mm (1 inch) forward of the forwardmost point on the ``leading
edge of the roof.'' Volkswagen also recommended setting a tolerance on
the 25 mm forward placement of the plate, to avoid problems of test
procedure implementation and interpretation. Ford recommended that the
NPRM's plate placement be adopted
[[Page 22570]]
as proposed, even though this represented a change from its petition
request. BMW suggested that the agency vary the position of the front
edge of the test plate within a range ``tangent to or up to a maximum
of 254 mm forward of the transverse vertical plane passing through the
forwardmost point on the exterior surface of the roof,'' depending upon
the distance that will ensure that the test plate avoids contacting the
length of the A-pillar during the test. GM, Volkswagen and BMW
supported their approaches by suggesting that the proposed test plate
location could possibly create complications in testing or possibly
produce unrealistic edge loading on the A-pillar.
GM commented that both the current and proposed positions of the
test plate will result in the front edge of the plate penetrating the
roof and the A-pillar for vehicles with a sharp transition between the
slope of the windshield and the roof structure, such as some pickup
trucks, based upon observations made on agency compliance testing for
Standard No. 216. It supported the 50 mm distance recommended by the
American Automobile Manufacturers Association (AAMA) because it
believed that will provide the necessary, consistent orientation of the
test plate over the front part of the roof and avoid plate edge contact
with the A-pillar.
GM suggested that the agency needs further data. It stated that it
knows of no data or analysis which would allow a determination of
whether the agency's proposed longitudinal positioning of the test
plate would be an improved test for all vehicles with uncommon roof
shapes or whether it would reduce the stringency of the current test
procedure. GM also recommended that if the agency's intent is to load
vehicle roof structures in a manner which simulates loading commonly
noted in rollover crashes, the agency should initiate a study to
determine the appropriateness of modifying the current test plate
angles to accommodate the range of vehicle designs and to determine the
appropriateness of changing the test plate application angles as well
as the test plate dimensions. It suggested such a study might involve
an analysis of real world crashes and roof geometry, followed by a
determination of the most representative orientation of vehicle to
impact surface for each vehicle type.
Volkswagen also stated that the placement proposed in the NPRM may
result in the edge of the plate contacting the roof and windshield
during the test and producing results which the proposal was intended
to avoid. Volkswagen commented that placing the plate one inch forward
of the front edge of the roof more positively assures loading to the A-
pillar and supporting roof structures.
BMW experienced complications during developmental testing, using
the current Standard No. 216, of future production vehicles with A-
pillar designs that slope at less than 31.5 degrees from the
horizontal. It believed that similar problems would also occur when
testing as proposed in the NPRM. BMW indicated that both procedures
resulted in the plate being positioned directly over the A-pillar, so
it expected the proposed placement to result also in contact between
the plate edge and the pillar during the test, producing variable and
unrealistic load-deflections and a lack of test repeatability.
To avoid edge loading of the A-pillar, BMW recommended that the
agency allow manufacturers to variably align the test device to achieve
the desired location. BMW suggested that the front edge be placed
``tangent to or up to a maximum of 10 inches in front of the transverse
vertical plane passing through the forwardmost point on the exterior
surface of the roof * * *.''
Ford stated ``the procedure proposed in the NPRM provides for a
repeatable method of test platen positioning for current vehicles being
manufactured with aerodynamic roof lines.'' Ford, however, stated that
it does not believe that the tests which were conducted by the agency,
using the current and NPRM's proposed roof crush test procedures, on
the Ford Taurus and the Dodge Neon provide a valid comparison between
the roof crush results obtained with both procedures because the agency
tested the vehicles twice, one side with the current procedure and the
other side with the proposed procedure.
Ford also stated that NHTSA should not assume that the forwardmost
point on the roof will always be at the vehicle's longitudinal
centerline. This assumption is implied because the agency's objective
of avoiding front plate edge penetration is only served using the
proposed language if the forwardmost point on the roof is in the
center. If the forwardmost point is along the sides near the A-pillars
then plate edge penetration could occur. Although Ford believed this is
a valid assumption for current production vehicles, to account for
possible future aerodynamic styling themes on which the forwardmost
point might be located outboard of the vehicle's longitudinal
centerline, Ford recommended that NHTSA revise the platen positioning
procedure to state ``[t]he midpoint of the forward edge of the lower
surface of the test device is tangent to the transverse vertical plane
passing through the forwardmost point on the exterior surface of the
roof, including trim, that lies in the longitudinal vertical plane
taken at any lateral position between a point 25 mm inboard of the left
and right A-pillar surface.''
Advocates took no position on the NPRM's proposed test plate
positioning, stating that the agency should first address the
differences in the real world load conditions for vehicles with
increasingly common highly sloped A-pillar or aerodynamic roof
structures, typified by ``cab forward'' occupant compartment designs.
Advocates stated that the roof structure of these vehicles make it
probable that B-pillars and the adjacent portions of the roof would
experience proportionally greater crash forces than in designs with A-
pillar/roof interfaces more closely approaching 90 degrees. Advocates
believes that the agency should explore this potential difference in
real world force loading for these vehicles so that it can make
substantial changes in rollover safety.
B. Altered or Raised Roofs (e.g., Van Conversions)
GM, Ford, RVIA, and the Minnesota DOT provided comments on the
agency's proposal to use a small test plate when the large plate would
result in initial contact rearward of the front seat area. Most opposed
the use of the small test plate, due to the belief that it would result
in rear edge loading.
GM and Ford were the only vehicle manufacturers that commented on
the agency's proposal to modify the size of the test plate for vehicles
with raised roofs. Both manufacturers disagreed with the proposed
change in certain circumstances of the test plate size from 30'' x 72''
to 24'' x 24''. However, each manufacturer had slightly different
reasons for opposing the small plate.
GM was concerned that the smaller test plate may not properly load
the B-pillar, which is also a significant roof structural member. GM
was also concerned that the smaller plate may still possibly make rear
edge contact with the modified roof section even when testing with the
proposed procedure and that if the agency were to accept the smaller
plate, additional cost would be incurred by manufacturers in either
revising or making new test fixtures to accommodate the different plate
sizes.
Ford concluded that the small plate is too small to be used and can
result in rear plate edge contact in some instances. Ford based this
contention on NHTSA's 1985 Buick Riviera roof crush data showing the
area crushed exceeded the surface area of the small plate by 12
percent. In addition, Ford calculated
[[Page 22571]]
that on a vehicle with a flat roof, the rear edge of the test plate
would contact the original roof surface after only 54 mm of
displacement, or 43 percent of the allowable travel. Ford stated that
testing with a smaller plate will increase the burden of demonstrating
compliance by final stage manufacturers of raised roof vehicles.
GM and Ford both recommended that the large plate be retained as
the only test device. GM suggested solving the testing problem posed by
raised roof vehicles by allowing the larger test plate to be located
``as far forward as necessary to achieve the desired loading
condition.''
RVIA stated that the smaller test plate will not resolve the
testing difficulties with raised roofs, but rather it will result in
edge contact between the modified roof and the edge of the test plate.
RVIA enclosed four photographs which it believed show a ``simulated
smaller test device roughly positioned at the test angle and position''
in minivan and sport utility vehicles with raised roofs. It suggested
the photos demonstrate that the rear edge of the proposed smaller test
plate contacts the raised section of the vehicle either before loading,
or would contact it following a small amount of displacement after
loading. It also commented that, even when using the larger test plate
(i.e., when the initial contact point of the test device is located at
the front portion of the roof over the front seat area) the rear edge
of the plate can contact the raised roof during the test if the roof
contour is raised behind the B-pillar. RVIA supported, however, NHTSA's
proposed definition of the rearward plane of the front seat area.
Minnesota DOT supported RVIA's recommendation to replace Standard
No. 216 with Standard No. 220 for modified roofs. To support its
recommendations, Minnesota DOT referenced two agency tests. The first
test was performed on a 1994 GM Safari according to the Standard No.
220 test procedure and the second test was on a 1992 Chevy Astro Van
according to the Standard No. 216 test procedure, modified as proposed
in the NPRM. Minnesota DOT concluded that the two procedures were
comparable due to equal amounts of roof deformation (or travel of the
test plates), and due to the fact that the Astro's modified roof
structure passed Standard No. 216 without loading the A-pillar
directly. Minnesota DOT further concluded that common alterations made
for modified roofs will not diminish the strength of the original front
roof structure. Therefore, Minnesota DOT disagreed with the agency's
determination that the Standard No. 220 test procedure is a less
stringent test, concluding instead that the two tests are comparable.
In addition, Minnesota DOT stated that it believes NHTSA is too
focused on A-pillar strength. It contends that the initial point of
contact with the roof in rollover crashes may not always be at the A-
pillar for vehicles with modified roofs forward of the driver's seat
back. It speculated that it is more likely that initial contact would
be with the raised roof area behind the driver that first contacts the
ground. The Standard No. 220 procedure is more likely to test the
raised roof portion. In any case, Minnesota DOT suggests that the real
issue should not be which components contribute to roof crush
resistance, but whether occupants are being protected. Crush resistance
provided by the A-pillar alone or by the A-pillar in combination with
other support structures should be irrelevant as long as the crush
requirements of the standard are met. Based upon these assumptions,
Minnesota DOT concluded that ensuring the integrity of the front roof
structure should not be of importance for vehicles with raised roofs,
especially for raised or modified roofs located behind the front seat
backs.
Advocates commented that the agency's proposed modification to
Standard No. 216 would not improve the extent to which the standard
addresses real world rollover crashes. Advocates stated that the agency
has no correlating data which shows relationships between the real
world roof crush, roof crush deformation for Standard No. 216 testing,
and the severity of injuries in rollover crashes. As a result,
Advocates offered no comments on the matter of revising the size of the
test plate.
C. Other Issues
1. Real World Rollover Crashes Versus Standard No. 216
Three commenters did not address their comments directly to the
NPRM proposal to clarify the test procedure of Standard No. 216 and to
remove complications in testing vehicles with modified or
aerodynamically sloped roofs. Instead, these commenters questioned the
appropriateness of the test procedure, in either its current or
modified form, as a proxy for real world rollover performance. In each
of the responses, commenters raised objections to the NPRM proposals,
as well as the current standard, as having no real relationship to the
causation of injuries and fatalities in rollover crashes.
Advocates and Liability Research Group (LRG), an independent
engineering research company, stated that the Standard No. 216
procedure was not sufficiently closely related to the real world
rollover environment. Advocates stated it could not support the NPRM
proposals due to the lack of a demonstrated relationship between
compliance with the current Standard No. 216 and the dynamic loads and
risk exposure of vehicle occupants during full rollover crashes. LRG
included a report titled, ``Rollover Crash Study--Vehicle Design and
Occupant Injuries,'' and concluded that the changes proposed in the
NPRM would not bring the standard any closer to its intent of reducing
deaths and injuries due to roof crush over the front seat area in
rollover crashes, but only refine the standard's test procedures.
Ricci, Hubbard, Leopold and Frankel (RHLF) responded to the NPRM by
stating that the agency should address more important crashworthiness
issues relevant to raised roofs instead of focusing solely on roof
crush resistance. It stated that it believes that raised fiberglass
roof conversions have a lack of ductility and are inadequately attached
to the frame of the vehicle by sheet metal screws. As a result, RHLF
contended that the raised roof section almost always fractures and/or
becomes detached during rollover crashes, creating a means for the
occurrence of ejection injuries and fatalities. Therefore, RHLF
believed that NHTSA's attention should be re-focused on this problem
and on the development of an adequate performance criteria for raised
roofs in the dynamic setting of the crash characteristics they
experience.
2. Variability in Standard No. 216 Testing
Ford initially petitioned the agency to clarify ambiguous test
procedures for vehicles with modified and sloped roofs. In its
petition, Ford also stated that it knew of other problems with the test
procedure that it would address with the agency at a later date.
Following the petition, Ford initiated a study to observe common test
practices by different test facilities and to assess the repeatability
of the load plate positioning during Standard No. 216 testing. Partial
results were submitted to the agency in response to the Request for
Comments. Ford submitted the rest of the information in a supplemental
report in response to the NPRM (Docket 94-097-N02-010). Ford's analysis
identified several issues related to test variability in roof crush
testing, test plate positioning, vehicle tie-down procedures, and
component definitions.
[[Page 22572]]
The supplemental report contained the test results of a
reproducibility study of three NHTSA contracted test facilities and the
Ford (Dearborn) test facility to observe the various laboratories' test
procedures and to assess the repeatability of load plate positioning
during Roof Crush Resistance testing. The non-Ford test facilities
included: MGA Research Corp. (MGA), General Testing Laboratories Inc.
(GTL), and Mobility Systems and Equipment Co. (MSE). Testing was
performed on 16 identical Ford Taurus vehicles, generally in accordance
with the Laboratory Test Procedure used for Standard No. 216 (TP-216-
04). The only notable differences from the test procedure were that the
vehicle windows were in the open/down position during the test, and the
test device continued to load the roof until 140 mm (5.5 in) of travel
was achieved rather than stopping if the minimum roof crush resistance
was met before the test device had traveled 127 mm (5 inches).
Summaries of the findings noted in each part of the testing are
provided below:
Roof Crush. In comparisons to Ford's testing, the average peak roof
crush loads from each of the non-Ford test labs were considerably
higher, except for MSE which had similar results. Based upon its
engineering judgment, Ford attributed the difference in the average
peak loads to differences in the design and operation of lab equipment,
differences in the accuracy and verification methods of each of the
labs, and variations in test vehicle-set up and procedural differences
including vehicle tie-down methods.
Plate Positioning. Based upon the results of the Ford analysis,
positioning the plate in accordance to Standard No. 216 produced a
range of 456 mm for the longitudinal plate placement measurements for
all the test labs surveyed. Independently, each lab also had large test
variations in longitudinal plate placement. A maximum range of 98 mm
was measured for one of the test sites. However, Ford expressed
confidence that the NPRM proposal regarding the test plate position
will serve to improve the longitudinal plate positioning repeatability
among all test facilities.
Vehicle Tie-Down Procedure. Ford stated that inconsistent use of
jackstands and the accompanying vehicle distortion may be a partial
source of the total roof crush variability found between the test
sites. Ford suggested that elimination of vehicle distortion as a
source of contact point movement and potential roof crush load
variability could be achieved by requiring consistent use of jackstands
to support the test vehicle's front and rear overhangs. Ford
recommended that the Laboratory Test Procedure be revised to state:
Jackstands must be located under the front and rear overhangs to
prevent distortion of the structure'' in order to support the
vehicle overhangs and minimize contact point movement as a potential
source of test variability.
Windshield Trim Definition. Ford recommended that the section
S7.2(e) proposed in the NPRM, which defines the proposed test plate
positioning procedure, be revised to clarify that the term ``trim''
pertains to the ``windshield trim.'' Ford also recommended that the
definition for windshield trim be included in Section S4. Ford
recommended that the definition for windshield trim should be
consistent with the definition recently established in the final rule
amending Standard No. 201, Occupant Protection in Interior Impact,
final rule (See, 62 FR 16718, at 16725):
Windshield Trim means molding of any material between the
windshield glazing and the exterior roof surface, including material
that covers a part of either the windshield glazing or exterior roof
surface.
3. Responses to Agency Questions in the NPRM
In response to questions asked or statements made by the agency in
the preamble of the NPRM, the following comments were provided.
Is the integrity of a roof structure on one side of a vehicle
altered by a test on the other side? GM and Ford both offered comments
on this issue. GM stated that, depending upon the level of damage
incurred in the first test, there may be an overlapping of structural
damage which could affect the test results of the test on the opposite
side, reducing the load bearing capacity considerably. Ford also stated
that it believes the roof structure integrity on the opposite side can
be compromised during the first test. Ford cited the agency testing on
the Dodge Neon and the Ford Taurus as an example of an invalid
comparison due to testing both sides of the roof structure.
The proposed positioning of the test load plate resulted in 17%
additional ``crush'' to a Dodge Neon during the test. NHTSA deems this
to be insignificant because it represents a displacement of only 8 mm.
GM agreed that the proposed modification to the procedure for
positioning the load plate could be adopted without an appreciable, if
any, reduction in test stringency. However, it did not agree with the
agency's dismissal of the differences in test results between the
current and modified procedures as insignificant. GM considers a l7
percent increase in crush to be a significant increase.
Is NHTSA's definition of ``roof over the front occupant
compartment'' appropriate? Ford agreed with the intent of defining the
rear boundary of the roof over the front seat area, but questioned how
NHTSA derived a distance of 162 mm rearward of the SgRP. Ford did not
agree with the definition because of the lack of supporting
information, and suggested that NHTSA perform further analysis of the
appropriate boundary.
GM and RVIA both stated that NHTSA's definition is satisfactory in
defining a rearward limit of the location of the front seat area.
However, GM stated that the location of the SgRP should not be based
upon the left front outboard seating position. GM recommended that the
SgRP be referenced from either the driver's seating position or the
rearmost of the front outboard seating positions, to ensure the proper
location for certain classes of vehicles where the driver's side can be
on the right side of the vehicle (e.g., postal and international
vehicles) or which have asymmetric design configurations where one
outboard SgRP may be different from the other.
If NHTSA increased the amount of allowable ``crush'' for vehicles
with raised roofs, what method should be used to take into account the
increased headroom resulting from such roofs? GM did not know of a
single method which could be applied to all raised roof vehicles. Some
raised roof conversions offer no increase in headroom (and in some
designs headroom is reduced) because they retain the original overhead
roof structure and then add interior roof consoles, trim, moldings,
etc. in the raised section. In some instances, the raised portion of
the roof over the front occupants is used for storage rather than
providing additional headroom.
RVIA also stated that it does not know of a method for determining
the differences between the raised roof surfaces and the original roof
surfaces of raised roof vehicles. However, it noted that in some raised
roof applications, the differences are such that roof crush of 127
millimeters or more would not approach the contour of the original roof
surface.
Advocates objected to the NHTSA's amenability to increasing the
amount of allowable roof crush for vehicle with raised roofs to
compensate for the increased headroom, if a suitable
[[Page 22573]]
method for measuring the additional headroom could be determined.
Although NHTSA agreed in principle with this manufacturer request, the
agency did not propose to adopt the requested action. Advocates also
asserted that not every vehicle modified with a raised roof actually
increases the amount of headroom in the front seat area due to the
installation of leisure equipment in these areas.
Should the proposed test procedure address glass panels or sunroofs
located over the front occupant compartment, and if so, how? The test
procedure currently requires that, prior to testing, windows and doors
are closed and removable or movable roof panels are in their closed and
latched positions. GM stated that it knows of no reason to change this
practice. RVIA commented that this glazing should be considered to be
part of the roof structure but that NHTSA's procedures should allow
testing ``with the glazing installed and any moveable glazing tested in
either the open or closed position as determined by the vehicle
manufacturer or converter.''
While this proposal does not involve changes to test load plate
angles, the NHTSA requests any available data on the subject. GM stated
that it has no applicable data but, as noted above, it suggested NHTSA
needs to further study the matter. Although they did not address
themselves specifically to the question, the comments of RHLF,
Advocates, and LRG indicate these organizations also believed that more
testing is needed.
Should the load plate be reduced in size from the current 30'' x
72'' to 24'' x 24'' for testing of vehicles with a raised or altered
roof structure located rearward of the front occupant compartment? GM
stated that if the agency's stated purpose for Standard No. 216 is ``to
reduce the likelihood of roof collapse over the front occupant
compartment in a rollover crash,'' it should abandon the small test
plate. GM stated that the smaller (24'' x 24'') test plate is
inappropriate because it is too small to produce crush loading
representative of the actual loading experienced by a vehicle during a
crash event.
V. Agency Discussion of Issues
A. Summary of Changes From the NPRM
In response to the comments, the agency is modifying the approach
it proposed in the NPRM. In particular, the agency was persuaded, for
the reasons explained below, that there were technical difficulties
associated with the use of a smaller test plate. Instead, it is
addressing the problems raised in the petitions by changing only the
test plate position. The major changes to the standard (or deviations
from the proposal) are summarized below.
(1) The size of the test plate for all testing will not change. It
will remain 762 mm (30 inches) x 1829 (72 inches) because the proposed
small test plate did not have enough surface area to crush a minimally
compliant vehicle without edge contact.
(2) The front edge of the test plate will be positioned tangent to
a vertical plane 254 mm (10 inches) horizontally in front of the
forwardmost point of the roof for all vehicles, except vehicles with
raised or modified roofs for which the initial point of contact with
the plate is rearward of the front seat area. This will consistently
position the plate over the front seat area. The amendments specify
that the roof includes the windshield trim. Further, the amendments
define windshield trim. In addition, the longitudinal placement of the
plate includes a tolerance of 10 mm. This increases the
enforceability of the standard.
(3) If a vehicle has a raised or modified roof structure and if the
initial point of contact is rearward of the front seat area, the
rearward edge of the plate will be positioned tangent to a vertical
plane passing through the rearmost point of the front seat area. This
will avoid testing the modified roof to the rear of the front seat
area. The longitudinal placement of the plate includes a tolerance of
10 mm.
(4) The definition for the roof over the front seat area has been
revised to account for vehicles with asymmetrical roofs and non-aligned
driver and passenger seating positions.
(5) To address the problem raised by Ford of mounting a vehicle's
sills or chassis frame, the agency notes that the problem of
interference between a vehicle's underbody and a single horizontal
surface can be solved by using two separate surfaces (e.g., I-beams)
located at the same height. Those two surfaces are the equivalent of a
single surface. The use of two separate surfaces allows the underbody
components to hang down without interference. As to Ford's concerns
about pre-stressing and rocking, the agency will address those matters
outside this rulemaking.
B. Plate Position for Sloped and Contoured Roofs
All commenters who addressed the issue, except Ford, opposed
positioning the front edge of the test plate tangent to the forwardmost
point on the roof, based mostly on concerns about the possibility that
the plate's front edge might penetrate the roof.
The agency based its proposal on the results of its compliance
testing and on the Vehicle Research and Testing Center's testing of
current production vehicles for research purposes. In the testing,
current production vehicles typically experienced between 1-3 inches of
maximum roof crush, occurring several inches rearward of the A-pillar.
Testing using the current and modified roof crush tests produced
comparable amounts of crush at exactly the same location on the roof.
Consequently, use of the modified procedure on conventional roof
structures should very rarely result in the front edge of the plate
contacting the A-pillar during testing.
Nevertheless, the arguments of these commenters have merit.
Especially for vehicles with a sharp transition between the slope of
the windshield and a relatively flat roof structure, such as light
trucks and vans, the agency agrees that front edge loading could occur
if the initial point of contact were close to the A-pillar or exactly
at the A-pillar joint. Front edge loading could also occur on future
production vehicles such as those mentioned by BMW with A-pillar angles
less than 31.5 degrees.
More important, front edge loading could also occur if the proposed
procedure were used in testing those vehicles which allow more than the
1-3 inches of crush experienced by most vehicles during compliance
testing. As noted above, the standard allows up to 5 inches of roof
crush. The test procedures must not be based on an assumption that
there will not be any vehicles who performance approaches that limit.
If five inches of roof crush were to occur when the plate had been
positioned according to the proposal, the front edge of the plate would
likely penetrate the roof or the A-pillar, even in the case of vehicles
with conventionally sloped roof structures.
Some of the recommendations by the manufacturers for pre-test
positioning of the front edge of the plate would also be unacceptable
for the same reason. A test plate positioned according to GM and VW's
recommendations (i.e., with the plate's front edge positioned 2 inches
and 1 inch, respectively, forward of the forward most point on the
roof) would also result in front edge contact with the A-pillar for a
minimally compliant vehicle with a current roof design.
NHTSA disagrees with part of BMW's comment that the test procedure
should allow the position of the front edge of the test plate to vary
at the discretion of
[[Page 22574]]
the manufacturer or final stage manufacturer. Although, theoretically,
varying the plate's front edge position by up to a range of 254 mm (10
inches) forward of the forwardmost point of the roof should make little
difference in the force application, the agency remains concerned that
variable test placement may increase the variability of the test
results. By not ensuring a fixed location point for the test plate,
variations in the test results as a result of test setup variability,
such as those noted by Ford in its variability study, might occur. It
is also rare for NHTSA to allow manufacturers to specify test
conditions during the agency's compliance testing. Such an allowance
would give the manufacturers some influence over the stringency of the
requirements and could result in differences in the stringency of the
requirements for different manufacturers. Further, the allowance seems
unwarranted when the problem (potential front edge loading) could be
addressed without introducing such a variable. In addition, NHTSA notes
that manufacturers already have this flexibility with respect to their
own testing. The test procedures in the Federal Motor Vehicle Safety
Standards specify how the agency will conduct compliance testing.
Manufacturers and converters may, at their risk, deviate from these
procedures so long as they are confident that the modified test still
provides an adequate basis for certification that their vehicles will
comply when tested by the agency in accordance with the standard.
The agency thinks there is merit in the portion of BMW's
recommendation to specify that the front edge of the test plate is to
be placed 254 mm (10 inches) forward of the forwardmost point on the
roof. NHTSA believes that if the plate were so positioned, its front
edge would not contact the roof or A-pillar of any current or future
vehicles. The agency is not aware of any vehicles, even minimally
compliant ones, with A-pillars so inclined that the plate's front edge
could contact the roof or the A-pillar. The agency does not foresee any
complications in the test procedure or change in the stringency of the
requirements as a result of shifting the plate 254 mm (10 inches)
forward, since the plate is so long that rear edge contact is highly
unlikely.
By moving the test plate sufficiently forward of the forwardmost
point of the roof, edge loading associated with the current procedure
will be eliminated for present and future production vehicles. Locating
the plate edge relative to a fixed point on the roof instead of the
initial contact point also addresses BMW's concern that future vehicles
with very inclined A-pillars might have roofs on which the initial
contact point is hard to determine. It is also suitable for vehicles
whose forwardmost point of the roof does not lie on the vehicle's
longitudinal centerline, because the roof at the top of the A-pillar
will not be more than 254 mm (10 inches) longitudinally forward of the
roof on the vehicle's centerline. Therefore, the agency is modifying
the rule to specify placement of the plate's front edge 254 mm
10 mm (10 inches .39 inches) forward of the
forwardmost point on the roof. This will limit the test variability,
while ensuring enforceability of the crush resistance requirement.
NHTSA agrees with Advocates that the low angle of inclination of
the A-pillar for vehicles with aerodynamic roof structures will likely
cause the B-pillar and the adjacent portions of the roof to bear
proportionally greater crash forces in rollover crashes, compared with
vehicles with more upright A-pillars. However, ensuring the structural
integrity of the A-pillar is of even greater importance in vehicles
with aerodynamic roof structures because the low slope of the A-pillar
may result in a shorter minimum distance from the A-pillar to the front
seat occupant's head. Therefore, this rule's emphasis on the A-pillar
is appropriate.
NHTSA agrees with those commenters that the agency should not limit
its efforts to refining the current test procedure, but should also
explore other, arguably more realistic, methods of testing for roof
crush strength that might lead to the possibility of greater
improvements in rollover safety. The purpose of this rulemaking is to
address only the issues of difficulty of testing raised in the
petitions. Other issues, such as the possibility of using a dynamic
test procedure or research into exploring differences between the
rollover crash forces in the roof structures of various roof/pillar
designs will be considered separately. The successful resolution of
those issues may enable the agency to consider rulemaking for upgrading
Standard No. 216.
C. Use of a Small Test Plate for Vehicles With Raised or Modified Roofs
All commenters that addressed the issue opposed the small test
plate and recommended continued use of only a large plate, mostly due
to concerns over the likelihood of rear edge loading. Other reasons
cited for opposing the small plate included failure to load the B-
pillar, additional cost of making new test fixtures and higher test
costs, and the possibility that the area crushed by the large test
plate would exceed the surface area of the small plate, resulting in
edge loading.
NHTSA agrees that the smaller test plate could result in rear edge
contacts with certain raised roof vehicles, especially if the roof were
minimally compliant. This would be particularly undesirable since the
rear edge loading would likely occur on the roof over the front seat
area. GM is correct in its statement that the small test plate would
ineffectively stress the B-pillar, but, as explained above, loading the
A-pillar and the roof section over the front seat area is the primary
concern of the agency. In addition, the Standard No. 216 test procedure
with the large plate in compliance testing results in little or no roof
crush at the B-pillar.
Primarily because of the likelihood of rear edge contact over the
front seat area of some vehicles, NHTSA agrees with these commenters
that a small test plate should not be adopted. This addresses
manufacturer concerns about additional costs of making new test
fixtures and higher test costs, and about the current plate crushing an
area greater than the surface area of the smaller plate. However,
retaining the large plate means that the problem with testing raised or
modified roofs needs to be addressed in another way.
The question becomes how to conduct testing with the large test
plate in a manner that addresses the concerns raised by RVIA in its
petition. The agency believes GM's recommendation to move the large
test plate forward far enough to ``achieve the desired loading
condition'' is not feasible. Allowing the position of the test plate to
vary by an amount thought to be necessary to avoid contacting the
raised section introduces a variable that would add to the test
variability cited by Ford in its study. It would make the standard less
objective, thus making compliance testing more difficult and reducing
the standard's enforceability. In addition, with certain modified roof
structures, the shape of the raised section might dictate moving the
plate so far forward that the rear edge is near the front of the front
seat area, resulting in very little of the plate contacting the roof.
Rear edge loading is especially likely in this situation.
Defining ``the desired loading condition'' may involve trade-offs.
For certain roof shapes, the agency sees no way to avoid both loading
the rear edge of the plate in the area over the front seat area and
loading the raised roof to the rear of the front seat area. If the
plate is far forward enough so that it misses the modified roof to the
rear of the front seat area, rear edge loading even with the larger
test plate can occur. This is because raised or modified roofs may
[[Page 22575]]
step up or slope up toward the rear of the front seat area, and the
shorter length of plate over the roof (i.e., the distance between the
front of the roof and the rear of the front seat area instead of the
full length of the plate) provides less distance for even the large
plate inclined toward the rear at a shallow angle to ramp up above the
roof surface. If the large plate is allowed to extend past the rear of
the front seat area, then portions of such a roof that are not over the
front seat area may support load, and may experience rear edge loading
anyway.
The agency concludes that the best way to test vehicles with raised
and modified roofs in accordance with the intent of the standard is to
align the rear edge of the test plate so that it is tangent to the
vertical plane passing through the rearmost point of the front seat
area. This essentially constitutes the agency's adoption of GM's
recommendation, specifying a fixed longitudinal position instead of a
variable position. Allowing the large test plate to be moved forward
will avoid rear edge contact with the majority of raised roofs with the
rear edge positioned as specified. It should not matter how far the
front of the plate projects in front of the roof.
This solution minimizes problems. Rear edge loading might occur in
testing a small number of vehicles with modified or raised roof
structures that slope or step upward at more than a five degree angle
between the front of the roof and the rear of the front seat area.
However, this is unavoidable without varying the plate angles and
position according to the roof geometry. The plate might never contact
the A-pillar if the raised or modified roof is more than five inches
above that structure, but this may be unavoidable regardless of the
plate size and angle. The agency's primary concern is that the test
plate loads the roof of the front seat area using a procedure that is
more objective and repeatable. This solution accomplishes that goal.
Retention of the larger plate also largely addresses GM's concern
regarding the potential increase in cost for designing test fixtures.
However, the requirement that the rearward edge of the long plate be
aligned with the rear of the front seat area when testing certain
raised roof vehicles, could necessitate some retooling for the
fixtures. There should not be any additional cost for those test
facilities which use two hydraulic cylinders to apply the loads to the
test plate. Test facilities that use a single hydraulic cylinder may or
may not be able to produce uniform loading upon the roof structure,
because of the torsion that would be applied to the connection between
the plate and the cylinder if only the rear half of the plate is in
contact with the vehicle. If upgrading single cylinder equipment is
necessary to compensate for this effect, the agency anticipates only a
minor, one time only, fixture cost.
The initial point of plate contact determines whether the rear edge
of the plate needs to be aligned with the rear of the front seat area.
If the initial contact point is above the front seat area, then the
normal plate positioning procedure is used. If the initial contact
point is to the rear of the front seat area, then the plate is
realigned.
NHTSA realizes that, after the plate has been realigned, if the
initial point of contact is only slightly forward of the rear of the
front seat area, then a small amount of the roof to the rear of the
front seat area might be crushed by the rear edge of the plate as it
moves downward and slightly rearward, perpendicular to its 5 degree
rearward inclination. This is only likely to happen if the roof is
minimally compliant. NHTSA's past compliance testing indicates this
would be a very rare occurrence. In any case, crushing a small amount
of roof to the rear of the front seat area is preferable to the rear
edge loading that would occur otherwise. If the initial point of
contact is to the rear of the front seat area, then rear edge loading
at the rear of the front seat area is preferable to the possibility
that the roof over the front seat area would never be tested by the
plate at all.
NHTSA disagrees with Minnesota DOT's analysis that ensuring the
integrity of the front roof structure should not be of primary
importance for vehicles with raised or modified roofs. Standard No. 216
stresses the area of the roof most likely to have occupants under it.
Standard No. 220 was adopted for vehicles which typically carry more
occupants in the rearward seating positions (i.e., school buses), which
is why the integrity over the entire roof structure is the primary
concern. Conversely, Standard No. 216 was adopted for vehicles which
typically carry front seat occupants (i.e., most light duty vehicles).
Thus, it is more important to ensure the integrity of the roof
structure over the front seat area. In addition, failure of the A-
pillar in these vehicles is more likely to cause harm than other parts
of the roof. Light duty vehicles, particularly mini-vans, are commonly
the type of vehicle whose roof structures are modified. Since 1990,
these vehicles have commonly been designed with more aerodynamic roof
structures. The design of aerodynamic roof structures effectively
places the A-pillar/roof joints in closer proximity to the heads of the
front seat occupants. Therefore, regardless of the initial point of
contact, it is more important to ensure roof integrity at the A-pillar
and adjoining roof structure.
The agency also disagrees with the portion of RVIA's analysis that
concludes Standard No. 220 is comparable to Standard No. 216 and is
preferable for testing vehicles with raised or modified roofs. NHTSA
stands by its tentative conclusion stated in the NPRM that the Standard
No. 220 test is less stringent than Standard No. 216 for testing the
appropriate roof area. Agency tests on a raised roof van using the
Standard No. 220 procedure resulted in the initial point of contact and
the maximum amount of deformation near the rear of the roof structure.
The proposed Standard No. 216 procedure, as well as the procedure
adopted in this final rule, has an initial point of contact and maximum
roof crush over the front seat area and near the A-pillar for
conventionally flat roof structures. Even though the maximum amounts of
roof crush in the two tests were comparable, the deformation at the A-
pillar junction was far less in the Standard No. 220 test. There are no
hard data on the issue of where initial contact with the ground
typically occurs in real world rollover crashes, so RVIA's conclusion
that the initial point of contact would be farther to the rear is
speculative. However, NHTSA's engineering judgement, based on an
analysis of NASS data conducted in the 1980s, is that real world
rollovers typically involve a component of forward velocity along with
the roll, which should generally result in the front occupant area
(e.g., the A-pillar and front edge of the roof) contacting the ground
first. Therefore, Standard No. 216 is a more appropriate test.
D. Other Issues and Concerns
1. Real World Rollover Crashes Versus Standard No. 216
Advocates and other commenters stated that agency's proposed
modification to Standard No. 216 would not improve the extent to which
the standard addresses real world rollover crashes. As stated earlier,
the purpose of this rulemaking is to address conflicts and ambiguities
in the existing test procedure. Major changes, such as changing from a
quasi-static to a dynamic roof crush test, are outside the scope of
this rulemaking and therefore must be considered separately.
The agency is taking steps to address the issue of substantive
changes to Standard No. 216. As part of NHTSA's Strategic Plan, which
details goals for
[[Page 22576]]
improving occupant protection in rollover crashes, the agency is
conducting research to explore the potential for reducing injuries and
fatalities resulting from harmful contact due to roof crush. The agency
is focusing on developing alternative test procedures for improving
roof crush resistance. A cumulative report that details the results of
NHTSA's research and compares quasi-static testing to dynamic testing
is currently available on NHTSA's Research and Development web page at
www.-nrd.nhtsa.dot.gov/vrtc/cw/roofcrsh.pdf. The report is also
available through the DOT docket, under docket number NHTSA-1996-1742.
NHTSA is also exploring a possible correlation between real world
rollover roof crush/injury data and the headroom reduction resulting
from the roof crush in these crashes. Following the completion of this
research, NHTSA will determine the next steps in upgrading rollover
occupant protection crashworthiness. Depending on the results of its
research, NHTSA may initiate a rulemaking to address whether Standard
No. 216 should be upgraded as a modified quasi-static test or whether
the adoption of a dynamic test should be considered.
RHLF commented that the raised roof section of some van conversions
detaches in rollover crashes due to the fiberglass material's reduction
in the ductility or energy absorption and inadequate attachment with
sheet metal screws by final stage manufacturers. NHTSA is not aware of
any industry-wide problem. Any problem found that is not common to a
substantial portion of the second/final stage manufacturers would be
addressed by NHTSA's defects program. NHTSA's Office of Defects
Investigation will continue to monitor this situation through its
complaint files and, if an apparent safety problem arises, the
appropriate action will be taken.
2. Test Variability in Standard No. 216 Testing
Ford expressed concerns regarding the variability in roof crush
testing and attributed that variability to differences in the design of
each test facility's lab equipment, the operation of the equipment, the
accuracy and verification methods of each test lab, and the test
vehicle setup including the tie-down procedures. The agency plans to
address these issues separately.
NHTSA agrees with Ford that the term ``trim'' in S7.2(e) describing
the proposed orientation of the test device, should be revised to say
``windshield trim'' because it is more specific. NHTSA also agrees that
the term ``windshield trim'' should be defined consistently with the
definition in Standard No. 201. Therefore, the same definition used in
Standard No. 201 has been incorporated in this final rule.
3. Analysis of Responses to Agency Questions in the NPRM
Is the integrity of a roof structure on one side of a vehicle
altered by a test on the other side? The agency agrees with GM and Ford
that if deformation as a result of a test on one side of a vehicle were
sufficiently extensive, it could cause overlapping damage that would
affect a second test. NHTSA asked the question in the NPRM mainly to
evaluate the effect of dual testing in previous research. The agency
conducts only one Standard No. 216 compliance test per vehicle.
The proposed positioning of the test load plate resulted in 17%
additional ``crush'' to a Dodge Neon during the test. NHTSA deems this
to be insignificant because it represents a displacement of only 8 mm.
NHTSA disagrees that the 17 percent increase in crush when using the
proposed procedure in the comparison test was a significant increase.
The test of the 1995 Dodge Neon was conducted first using the proposed
test plate position on one side of the vehicle, and then using Standard
No. 216's requirement on the other. The testing resulted in the
proposed test procedure producing 53.5 mm of crush and 45.8 mm for the
current procedure. The absolute difference in roof crush between the
two procedures was only 7.7 mm (0.3 inches). This amount of variation
in the test results between similar Standard No. 216 compliance tests
should be expected when using the current Standard No. 216 procedure.
Compliance testing (conducted at MGA Research Corporation) on two
similar 1985 Buick Rivieras and two 1984 Ford Crown Victorias (agency
compliance tests 624784, 624786, 627293, and 627488, respectively)
resulted in a difference of 0.2 inches in roof crush for the Ford
models and 1.09 inches for the GM models. Therefore, it is not
reasonable to assume that the revised procedure will always result in
significantly more crush.
In Ford's supplemental response to the NPRM, it stated that the
setup procedure for Standard No. 216 can cause considerable variations
in repeatability. Ford stated that, based upon its engineering
judgement, potential differences in the loading could result from the
unique design or operational characteristics of the lab equipment, the
equipment accuracy, the verification methods, and the test vehicle set-
up (i.e., vehicle tie-down methods). Theoretically, the revised
procedure would make no difference at all in the amount of crush, since
the plate orientation and size, and its initial point of contact with
the roof structure have not changed. The agency will consider setup
procedure issues.
Is NHTSA's definition of ``roof over the front occupant
compartment'' appropriate? In response to Ford's questioning how NHTSA
derived a distance of 162 mm rearward of the SgRP, the agency derived
that number from S8.11(a)(1) of Standard No. 201, Occupant Protection
in Interior Impact. It represents the distance from the SgRP to the
center of gravity of the 50th percentile male Hybrid III dummy.
NHTSA agrees with GM's recommendation that the definition of the
rear of the front seat area be revised to account for certain classes
of vehicles where the driver's side can be on the right side of the
vehicle (e.g., postal and international vehicles) or which have
asymmetric design configurations in which one outboard SgRP may be
different from the other. Therefore, the agency has revised the
definition of ``roof over the occupant compartment'' to reference ``a
transverse vertical plane passing through a point 162 mm rearward of
the SgRP of the rearmost front outboard seating position * * *''
If NHTSA increased the amount of allowable ``crush'' for vehicles
with raised roofs, what method should be used to take into account the
increased headroom resulting from such roofs? NHTSA shares Advocates'
concerns about the idea of allowing increased amounts of roof crush for
vehicles with modified/raised roofs. The agency agrees that there are
no existing data that will justify relaxing roof crush limits. The
agency is also aware that not all vehicles with a modified or raised
roof will have increased head room. Storage space added above the
occupants' heads may eliminate the headroom added by raising the roof.
In addition, the agency's concern expressed in the NPRM with
practicability of testing was not addressed by any commenter. Due to
these valid concerns, NHTSA is not increasing the allowable amount of
crush for these vehicles, but will maintain uniform requirements with
all types of roof structures.
Should the proposed test procedure address glass panels or sunroofs
located over the front occupant compartment, and if so, how? The test
procedure currently requires that, prior to testing, windows and doors
are closed and removable or movable roof panels are in their closed and
latched positions. GM
[[Page 22577]]
stated that it knows of no reason to change this practice. Neither does
the agency. NHTSA rejects RVIA's suggestion that the roof should be
tested in either the open or closed position, at the discretion of the
manufacturer, because that would make the standard less objective.
While this proposal does not involve changes to test load plate
angles, the NHTSA requests any available data on the subject. No data
were known to the commenters. However, NHTSA's Vehicle Research and
Testing Center has generated a limited amount of data on this subject.
These results are incorporated in the agency's report on static versus
dynamic testing which is available in the docket and on the agency's
web site (www.nhtsa.dot.gov).
Should the load plate be reduced in size from the current 30'' x
72'' to 24'' x 24'' for testing of vehicles with a raised or altered
roof structure located rearward of the front occupant compartment? As
discussed above, due to concerns about rear edge plate loading over the
front seat area, the agency will retain the larger test plate for all
Standard No. 216 testing.
VI. Changes to the Regulatory Text
Substantial changes to the regulatory text are being adopted,
although the substance of the regulation remains largely the same. To
accommodate the insertion of a definitions paragraph (customarily
located at the beginning of NHTSA's standards), all subsequent
paragraphs, i.e., those beginning with S4, are being renumbered.
Essentially the same requirements were repeated three times in the NPRM
and twice in the existing standard, with the only difference being an
absolute limit on the amount of force for passenger cars and, in the
NPRM, the location of the initial contact point of the test plate on
raised roof vehicles. To eliminate that redundancy, these paragraphs of
the requirements section have been consolidated, with the differences
in the requirements clearly described.
Paragraph S7.2 has been rewritten to clarify, but not change, the
process of orienting the test plate and lowering so that it makes
initial contact with the vehicle being tested. In addition, the agency
is making a number of clarifying minor changes to the regulatory text.
In particular, a sentence was added to the test procedures to
explicitly specify that non-structural components such as roof racks
are removed prior to testing. This was already the agency's
interpretation of the current test procedure. The word ``accidents'' in
S2 is replaced with the word ``crashes.'' Figure 1 is revised to
reflect the new plate positioning procedure.
VII. Lead Time
The agency proposed a lead time of 180 days and requested comments
on that issue. In its two comments in response to the NPRM, Ford did
not renew its earlier request for a five year lead time, but instead
stated that 180 days was reasonable. VW commented that 180 days was
reasonable, and no other commenter addressed the issue. This action is
being taken at the manufacturers' request. To the extent that test
plate placement differs from the current procedures, it should make
compliance with the standard easier for all vehicles, since engagement
of the A-pillars is assured. No changes in vehicle design will be
necessary. Likewise, no changes in equipment will be necessary, except
for the possibility that some test facilities might have to add an
additional hydraulic cylinder to the existing large plate. In NHTSA's
judgement, this can be accomplished within 180 days. Consequently, the
changes to Standard No. 216 will become effective, and compliance will
be required, 180 days following the publication of the final rule.
However, manufacturers may voluntarily comply with this rule earlier.
VIII. Rulemaking Analyses and Notices
A. Executive Order 12866 and DOT Regulatory Policies and Procedures
This rulemaking document was not reviewed under E.O. 12866,
``Regulatory Planning and Review.'' This action has been determined to
be ``non-significant'' under the Department of Transportation's
regulatory policies and procedures. The changes made by this rule will
not impose any new requirements, but simply clarify existing test
procedures and allow them to be applied consistently to the intended
area of the roof on all vehicles. Thus, this rule will not require any
design changes and will not cause any increase in compliance costs,
except as noted below in the discussion of test equipment under the
Regulatory Flexibility Act. The impacts of the rule are so minor that a
full regulatory evaluation is not required.
B. Regulatory Flexibility Act
NHTSA has also considered the impacts of this rule under the
Regulatory Flexibility Act (beginning at 5 U.S.C. 601). I certify that
this rule will not have a significant economic impact on a substantial
number of small entities.
The following is NHTSA's statement providing the factual basis for
the certification (5 U.S.C. 605(b)). The final rule primarily affects
passenger car, light truck, and multipurpose passenger vehicle
manufacturers. It also affects a substantial number of van conversion
shops and a small number of independent test facilities that perform
Standard No. 216 testing. The Small Business Administration's size
standards (13 CFR part 121) are organized according to the Standard
Industrial Classification Codes (SIC). SIC Code 3711 ``Motor Vehicles
and Passenger Car Bodies'' has a small business size standard of 1,000
employees or fewer. Virtually none of the vehicle manufacturers are
small entities under that standard. NHTSA does not know the number of
employees at a typical test facility, but there are not a substantial
number of these businesses. NHTSA also does not know the number of
employees typically employed by the van conversion shops (i.e., the
final stage manufacturers and alterers), but it assumes that they are
few in number, and that a substantial number of these businesses would
qualify as small entities.
However, there will be no significant economic impact on any
entity. As explained above, the rule does not impose any new
requirements but instead clarifies the test procedures and allows them
to be applied to the areas of the roof to which they were originally
intended. There is a possibility that some vehicles with raised roofs
to the rear of the front seat area will now have to be tested with much
of the test plate projecting forward from the roof, such that a single
hydraulic cylinder centered on the plate may not be sufficient to
stabilize the plate during testing. In this case, a few test facilities
might have to modify their test equipment by adding a second hydraulic
cylinder, but NHTSA does not consider the changes to be a significant
economic impact. The conversion shops are already responsible under the
current test procedures for recertifying compliance with Standard No.
216 if they affect the roof structure. This rule will not have any
effect on the price of new vehicles purchased by small entities.
C. Paperwork Reduction Act
NHTSA has analyzed this rule in accordance with the Paperwork
Reduction Act of 1980 (Public Law 96-511). There are no requirements
for information collection associated with this rule.
[[Page 22578]]
D. Executive Order 12612 (Federalism)
NHTSA has analyzed this rule in accordance with the principles and
criteria contained in E.O. 12612, and has determined that this rule
will not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
E. Civil Justice Reform
This rule will not have any retroactive effect. Under 49 U.S.C.
30103, whenever a Federal motor vehicle safety standard is in effect, a
State may not adopt or maintain a safety standard applicable to the
same aspect of performance which is not identical to the Federal
standard, except to the extent that the state requirement imposes a
higher level of performance and applies only to vehicles procured for
the State's use. 49 U.S.C. 30161 sets forth a procedure for judicial
review of final rules establishing, amending or revoking Federal motor
vehicle safety standards. That section does not require submission of a
petition for reconsideration or other administrative proceedings before
parties may file suit in court.
List of Subjects in 49 CFR Part 571
Imports, Motor vehicle safety, Motor vehicles, Reporting and
recordkeeping requirements.
In consideration of the foregoing, 49 CFR part 571 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;
delegation of authority at 49 CFR 1.50.
2. Section 571.216 is amended as follows:
a. S2 is revised.
b. S4 is revised.
c. S5 is revised.
d. S6 is revised, and S6.1, S6.2, 6.3 and S6.4 are removed.
e. S7, S7.1, S7.2, S7.3, S7.4, S7.5, and S7.6 are added.
f. A heading is added preceding Figure 1 at the end of the section
and Figure 1 is revised.
The additions and revisions read as follows:
Sec. 571.216 Standard No. 216; Roof crush resistance.
* * * * *
S2. Purpose. The purpose of this standard is to reduce deaths and
injuries due to the crushing of the roof into the occupant compartment
in rollover crashes.
* * * * *
S4. Definitions.
Altered roof means the replacement roof on a motor vehicle whose
original roof has been removed, in part or in total, and replaced by a
roof that is higher than the original roof. The replacement roof on a
motor vehicle whose original roof has been replaced, in whole or in
part, by a roof that consists of glazing materials, such as those in T-
tops and sunroofs, and is located at the level of the original roof, is
not considered to be an altered roof.
Raised roof means, with respect to a roof which includes an area
that protrudes above the surrounding exterior roof structure, that
protruding area of the roof.
Roof over the front seat area means the portion of the roof,
including windshield trim, forward of a transverse vertical plane
passing through a point 162 mm rearward of the SgRP of the rearmost
front outboard seating position.
Windshield trim means any molding, other than rubber molding and
bonding adhesive, that is located over either the windshield glazing,
the exterior roof surface or both.
S5. Requirements. When the test device described in S6 is used to
apply a force to either side of the forward edge of a vehicle's roof in
accordance with the procedures of S7, the lower surface of the test
device must not move more than 127 millimeters. The applied force in
Newtons is equal to 1.5 times the unloaded vehicle weight of the
vehicle, measured in kilograms and multiplied by 9.8, but does not
exceed 22,240 Newtons for passenger cars. Both the left and right front
portions of the vehicle's roof structure must be capable of meeting the
requirements. A particular vehicle need not meet further requirements
after being tested at one location.
S6. Test device. The test device is a rigid unyielding block whose
lower surface is a flat rectangle measuring 762 millimeters by 1,829
millimeters.
S7. Test procedure. Each vehicle must be capable of meeting the
requirements of S5 when tested in accordance with the procedure in S7.1
through 7.6.
S7.1 Place the sills or the chassis frame of the vehicle on a rigid
horizontal surface, fix the vehicle rigidly in position, close all
windows, close and lock all doors, and secure any convertible top or
removable roof structure in place over the occupant compartment. Remove
roof racks or other non-structural components.
S7.2 Orient the test device as shown in Figure 1 of this section,
so that--
(a) Its longitudinal axis is at a forward angle (in side view) of 5
degrees below the horizontal, and is parallel to the vertical plane
through the vehicle's longitudinal centerline;
(b) Its transverse axis is at an outboard angle, in the front view
projection, of 25 degrees below the horizontal.
S7.3 Maintaining the orientation specified in S7.2--
(a) Lower the test device until it initially makes contact with the
roof of the vehicle.
(b) Position the test device so that--
(1) The longitudinal centerline on its lower surface is on the
initial point of contact, or on the center of the initial contact area,
with the roof; and
(2) Except as specified in S7.4, the midpoint of the forward edge
of the lower surface of the test device is within 10 mm of the
transverse vertical plane 254 mm forward of the forwardmost point on
the exterior surface of the roof, including windshield trim, that lies
in the longitudinal vertical plane passing through the vehicle's
longitudinal centerline.
S7.4 If the vehicle being tested is a multipurpose passenger
vehicle, truck, or bus that has a raised roof or altered roof, and the
initial contact point of the test device is on the raised roof or
altered roof to the rear of the roof over the front seat area, the
plate is positioned so that the midpoint of the rearward edge of the
lower surface of the test device is within 10 mm of the transverse
vertical plane located at the rear of the roof over the front seat
area.
S7.5 Apply force so that the test device moves in a downward
direction perpendicular to the lower surface of the test device at a
rate of not more than 13 millimeters per second until reaching the
force level specified in S5. Guide the test device so that throughout
the test it moves, without rotation, in a straight line with its lower
surface oriented as specified in S7.2(a) and S7.2(b). Complete the test
within 120 seconds.
S7.6 Measure the distance that the test device moved, i.e., the
distance between the original location of the lower surface of the test
device and its location as the force level specified in S5 is reached.
BILLING CODE 4910-59-P
[[Page 22579]]
Figure 1 to Sec. 571.216
[GRAPHIC] [TIFF OMITTED] TR27AP99.032
Issued on: April 14, 1999.
Ricardo Martinez,
Administrator.
[FR Doc. 99-10316 Filed 4-26-99; 8:45 am]
BILLING CODE 4910-59-C