[Federal Register Volume 63, Number 102 (Thursday, May 28, 1998)]
[Rules and Regulations]
[Pages 29139-29143]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-14110]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
[Docket No. NHTSA-98-3870; Notice 7]
RIN 2127-AG81
Federal Motor Vehicle Safety Standards; School Bus Pedestrian
Safety Devices
AGENCY: National Highway Traffic Safety Administration (NHTSA), DOT.
ACTION: Final Rule.
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SUMMARY: The agency is amending Standard No. 131, School Bus Pedestrian
Safety Devices, to permit the use of additional light sources on the
surface of retroreflective stop signal arms and to permit a certain
amount of the retroreflective surface to be obscured by mounting
hardware. It also makes minor clarifications to the standard. This
responds to a petition from Transpec, Inc., a maker of stop arms.
DATES: This rule will become effective on May 28, 1998. Petitions for
reconsideration of this rule must be received no later than July 13,
1998.
ADDRESSES: Petitions for reconsideration should refer to the docket
number and notice number and be submitted in writing to: Administrator,
National Highway Traffic Safety Administration, Room 5109, 400 Seventh
Street, SW, Washington DC, 20590. Telephone: (202) 366-5267
FOR FURTHER INFORMATION CONTACT:
For technical issues: Mr. Charles Hott, Office of Crashworthiness
Standards, National Highway Traffic Safety Administration, 400 Seventh
Street, SW., Washington, D.C. 20590 (202) 366-0247.
For legal issues: Mr. Paul Atelsek, Office of the Chief Counsel,
NCC-20, telephone (202) 366-2992, FAX (202) 366-3820.
SUPPLEMENTARY INFORMATION:
1. Background
Federal Motor Vehicle Safety Standard No. 131, School bus
pedestrian safety devices requires each new school bus to be equipped
with a stop signal arm. A stop signal arm is a device, patterned after
a conventional ``STOP'' sign, that automatically extends outward from
the bus to alert motorists that a school bus is stopping or has
stopped.
To ensure the conspicuity of a stop signal arm, Standard No. 131
specifies that the device must either be reflectorized or be equipped
with flashing lamps. If reflectorization is used to comply with the
standard, ``the entire surface of both sides of the stop signal arm''
must be reflectorized (S5.3.1, emphasis added). NHTSA has interpreted
this language to mean that Light Emitting Diodes (LEDs) outlining the
word ``Stop'' on the stop arm blade would not be permitted under the
reflectorization option because LEDs do not meet the requirements for
reflectorized material.
Transpec, Inc. (Transpec) submitted a petition for rulemaking
requesting that S5.3.1 of the standard be amended to allow the use of
LEDs on stop signal arms. The petition sought to amend the section to
permit red LEDs on the surface of the stop arm that are ``contained
within a light channel not greater than 10mm (.394 inches) wide
centered within the stroke width of each letter.'' Under the requested
amendment, the minimum stroke width of letters containing LEDs would be
increased from 20 mm (0.79 inches) to 25 mm (0.8984 inches). The LEDs
would be required to flash at the rate specified for stop arm lamps
conforming to S5.3.2. The petition also sought to permit a percentage
of the surface area of the stop arm to be obscured by mounting brackets
and other necessary components, with the aggregate area obscured by the
LEDs and other components not to exceed 7.5 percent of the surface area
of the stop arm.
2. The Notice of Proposed Rulemaking (NPRM)
On August 6, 1997, the agency published a NPRM proposing to amend
the standard in most ways as requested by Transpec. It proposed to
permit light to be emitted ``from the surface of each letter or from
the area immediately surrounding each letter'' in the legend ``STOP.''
Lamps on the surface of the letter would have to be located on the
centerline of each letter, or outline each letter of the legend. The
lamps on the surface of the stop arm would have to flash in the same
manner as specified for the lamps in non-reflectorized stop arms. The
net stroke width (i.e., the stroke width minus the width of the legend
lamps) of each letter containing lamps was proposed to be at least 15
mm, to assure that an acceptable amount of white letter reflectorized
surface would be provided.
Rather than limit the permitted light sources to LEDs, the agency
was more flexible than requested, proposing to permit almost any type
of light source in the legend lamps. It proposed to permit white lamps
as well as red lamps, but not both colors simultaneously, on the
assumption that
[[Page 29140]]
white lamps might better illuminate the white letters. It also proposed
amending S6.2.2.1 to eliminate the word ``filament,'' in order to
permit other non-filament light sources to be used in the legend lamps.
It also clarified that a requirement on the ``off'' cycle time of
gaseous discharge lamps applied only to xenon short-arc discharge
lamps.
The agency proposed to permit ``mounting brackets, bolts, or other
components necessary to the mechanical or electrical operation of the
stop signal arm'' to obscure up to 7.5 percent of the total surface
area of either side of the stop arm, and up to 10 percent of the white
border.
Finally, the NPRM clarified that when two stop arms are installed
on the same side of a bus, the forward side of the rearmost stop signal
shall not be reflectorized. This was done to avoid confusing drivers in
the lanes of opposing traffic as to where they should stop relative to
the school bus.
The agency also requested comment on a wide range of issues,
including: (1) comments and test data about the effectiveness of LED-
equipped stop signal arms as a means of enhancing stop arm conspicuity,
(2) the use of other light sources, such as miniature incandescent and
neon light sources, and their effectiveness, and the possibility of
confusion from mixed light sources, (3) whether to allow use of either
red or white LEDs or other light sources, or to allow only one color of
emitted light, (4) whether 7.5 percent, the percentage of permitted
obscuration requested by Transpec, is an appropriate amount, (5) what,
if any, intensities and test procedures should be required for lamps
used on stop arms. In addition, the agency noted that the Society of
Automotive Engineers' standards referenced in FMVSS 131 are not current
and asked if it would be useful to update some or all of these to the
latest versions and if there would be any burden associated with making
such changes, (6) whether light sources should be allowed to outline
each letter rather than be centered on each letter, and (7) whether an
immediate effective date is appropriate.
3. Summary of Comments
Comments were submitted by sixteen State departments of education
or school districts, Mr. Harry Gough, P.E., and two stop arm
manufacturers, Transpec and Specialty Manufacturing. Six of the school
district comments were forwarded by Transpec. Two national student
transportation organizations commented, the National School
Transportation Association (NSTA) and the National Association of State
Directors of Pupil Transportation Services (NASDPTS).
The Florida Department of Education conducted a comparative test
program involving school buses and three stop arm designs: standard
reflective stop arms with incandescent lights; stop-arms using strobe
lights; and Transpec LED-equipped stop arms. Fifteen different Florida
school districts tested the three stop arm designs for 20 school days
each. Although the results were not statistically significant, the
Florida study concluded that the LED and the strobe lighted stops were
``no less effective'' at stopping traffic than the incandescent lighted
stop arms Florida currently uses. The study also concluded that the raw
data tend to indicate ``some improvement'' at stopping traffic by both
the strobe and the LED type stop arms over the incandescent lighted
stop arm. The strobe lighted stop arm had a ``small advantage'' over
the LED stop arm at stopping traffic.
All other commenting States and school districts that had conducted
pilot tests liked the Transpec LED stop arm. Most stated that it
reduced the number of illegally passing motorists and was more visible
than the ``standard'' stop arm, although it was not always clear what
they were comparing it to.
Most commenters that addressed the issue supported the idea of
allowing other light sources. Transpec stated that NHTSA should
establish performance requirements for other light sources, but that
NHTSA's consideration of other light sources should not delay the
implementation of LEDs.
No commenters objected to the use of other light sources. Transpec
submitted the only comment to address the potential for confusion
caused by the LEDs and other light sources. It stated that the
potential confusion would not be so great as the confusion caused
between the flashing lights and reflectorized versions already allowed
by the standard.
A number of commenters expressed the opinion that only red lights
should be permitted in or around the legend. NSTA, Transpec and
Specialty all commented that these lights should be red because red is
the color that is currently used in all traffic lights that denote that
the motorist must stop. Transpec stated that white lights do not create
in a driver the same sense of urgency as red lights. In addition,
Transpec stated that white lights introduce a third lighting color
(i.e., red, amber, and white) to the school bus that could detract from
the ``STOP'' message.
Two commenters were concerned about the intensity of LEDs.
Specialty believed that LEDs were less visible when viewed from an
angle (as when viewed across multiple lanes) and that side angle
viewing should be studied. It also believed that LEDs are less visible
when viewed in direct sunlight. In contrast, a school district that had
pilot tested the LED stop arm believed that LEDs were more effective
than the incandescent lights in bright sunshine. Specialty provided
test results showing that LEDs do not pass the light specifications for
incandescent lamps in Society of Automotive Engineers Recommended
Practice J1133, School Bus Stop Arms. Mr. Gough also stated that, based
on testing, LEDs produce only one third the intensity of light as
incandescent lamps. He stated that NHTSA should establish minimum
intensity levels for LEDs.
Transpec indicated that it had developed a prototype LED-equipped
stop arm with the LEDs outlining the word stop, but that the design was
flawed because it had a ``Christmas tree'' effect (i.e., appearing as a
random field of lights distracting the observer and resulting in
diminished readability). Transpec urged NHTSA not to allow such a
configuration of lights unless further testing was conducted.
The only commenter to address the appropriateness of allowing
obscuration of up to 7.5 percent of the retroreflective surface of the
stop arm was Specialty. Specialty stated that the proposed 7.5 percent
figure was too great, and that obscuring more than 2 or 3 percent of
the retroreflective material would significantly reduce the
effectiveness of the stop arm because the retroreflective material does
the work of alerting the motorist.
Comment was mixed on the appropriateness of obscuring up to 10
percent of the white border of the stop arm. Specialty believed that
limiting the border obscurement to 10 percent may cause some difficulty
in mounting because some stop arms would have to be positioned farther
outward, which it believes would cause them to protrude so far out from
the side of the school bus that the bus would exceed the maximum width
under some State laws. Some states have laws that limit the distance a
stop arm can extend from the side of a school bus. Requiring that no
more than 10 percent of the border be obscured would lead to additional
tooling cost for manufacturers. However, the NSTA stated that 10
percent was an appropriate maximum.
[[Page 29141]]
4. Discussion
A. Stop Arm Effectiveness
NHTSA agrees with the commenters who stated that effectiveness
should be the prime consideration in whether or not to amend the
standard. NSTA expressed doubt that adding lights would solve the
problem of illegally passing motorists, but both it and the NASDPTS
stated that NHTSA should base its decision on ultimate effectiveness.
All field testing indicates that the Transpec stop arm is at least as
effective as other stop arms that the agency permits in preventing
motorists from illegally passing. The agency found the Florida study to
be the most helpful because it was the largest study to provide
comparative data.
Although statistically significant data would be preferable, the
agency is not constrained from acting without it. The reactions to the
field tests of the LED-equipped stop arm were positive, and NHTSA
considers this a sufficient basis on which to act. The Clark County
(Nev.) School District, for example, has employed over 230 school buses
equipped with the LED stop arm over the past five months and feels they
are superior. Considering the positive test results, the agency has
decided to permit LED-equipped stop arms.
B. Alternative Light Sources
The agency agrees with Transpec that the standard should not
prevent other light sources from being used in the legend of the stop
arm. No commenter opposed other light sources. The agency notes that
Standard No. 131 is a design standard only to the extent that it
promotes uniformity. The agency did not propose to allow only LEDs as
additional light sources, as Transpec's comment implies. Any light
source that meets the performance requirements of this rule is
permitted.
C. Intensity of Lights in the Legend
Specialty and Mr. Gough expressed concern over the lower intensity
of LEDs and the inability to see them at angles or in bright sunlight,
and encouraged the agency to set intensity requirements. Transpec also
suggested that NHTSA set performance standards for light sources other
than LEDs. However, at this time there are no industry standards for
the intensity of lights used in the legend of school bus stop arms.
As stated above, the primary consideration is effectiveness. In the
field testing, the LEDs that are currently used in the legend of stop
arms did not appear to have a negative effect on a driver's ability to
see the extended stop arm. Therefore, the agency does not believe there
is currently a need to set intensity requirements. NHTSA will monitor
the situation closely. Should manufacturers offer excessively dim
lights that do not adequately substitute for the light ``lost'' by
obscuring the retroreflective material, or excessively bright lights
that interfere with the drivers' of other vehicles ability to see, the
agency will consider developing intensity requirements.
D. Color of Light Sources
The agency finds persuasive the arguments of NSTA, Transpec and
Specialty that lights in the legend should be red and not white. Red is
the color that is currently used in all traffic lights that denote that
the motorist must stop (e.g., brake lights, traffic lights, railroad
crossing lights). Therefore, the rule has been modified from the
proposal to state that red is the only light color that is acceptable
in the legend of school bus stop arms.
E. Amount of Retroreflective Surface That May Be Obscured
Only Specialty commented on the amount of surface area and white
border that could be obstructed on a school bus stop arm. The NPRM
proposed that no more that 7.5 percent of the total surface area be
obstructed. Specialty questioned whether 7.5 percent was needed,
stating that no more than 2-3 percent of the total surface area of
current stop arm designs will be obstructed by the wires and support
clips running to surface mount lamps. Specialty also suggested that
permitting the obscuration of 7.5 percent of the reflective surface
could have a safety impact. It stated that the more retroreflective
material that is obscured, the less noticeable the stop arm becomes. It
concluded that obscuring more than 2-3 percent of the retroreflective
material would significantly reduce the effectiveness of the stop arm.
During a May 7, 1998 telephone conversation with Specialty's
Engineering Manager, Specialty revised its position on this issue. It
referred to an industry-wide market survey of current stop arms showing
that mounting brackets currently obscure up to 6.3 percent of the
retroreflective material. Since a small amount of additional
retroreflective material might be obscured by bolts and other necessary
components, Specialty now takes the position that permitting up to 7.5
percent obscuration is appropriate, since it is needed by the industry
for current designs, and would not significantly reduce the
effectiveness of the stop arm.
Ultimately, there was no opposition to permitting 7.5 percent
obscuration. The market survey referred to by Specialty adds support
for the proposed amount by indicating that current stop arm designs
require this provision. Therefore, the proposed 7.5 percent obscuration
permitted for brackets, bolts, or other components is retained in the
final rule.
F. Amount of White Border That May Be Obscured
The amount of white border that may be obstructed proved to be more
controversial. The NPRM proposed allowing up to 10 percent of this
border be obstructed. Specialty argued that more of the border should
be allowed to be obstructed for two reasons.
First, Specialty attempted to define the role of the white border.
It argued that the purpose of the white border is to provide a clear
border definition and an enhanced contrast between the retroreflective
material and the background (i.e., the area behind the stop arm).
Specialty concluded that ``the border does not alert [the] motorist to
the stop arm, the retroreflective material does that.''
This argument is not persuasive because, as stated in NHTSA's
November 1, 1995 interpretation to Specialty, the ``entire surface'' of
the stop arm is required to be reflectorized, including the white
border. Since the white border is retroreflective, it contributes to
the light returning to the drivers of other vehicles, while the area
that NHTSA is allowing to be obstructed does not. As Specialty noted,
the white border also provides contrast. Therefore, NHTSA also
considers the border to be important in attracting the motorist's
attention.
Second, Specialty argued that stop arms require mounting brackets
to mount the stop arm to the school bus and the mounting brackets may
obscure part of the border, and that requiring no more than 10 percent
of the border to be obscured would lead to additional tooling costs for
manufacturers to devise methods for putting the stop arm blades further
outboard without violating State laws.
This argument is persuasive. It was not the intent of the NPRM to
change the way existing stop arms are mounted on school buses. The
intent was to provide a basis for the amount of white border that could
be obstructed by mounting and operational hardware. Some obscuration is
a practical necessity for mounting the stop arm blade in a cost-
effective manner. Specialty did not offer the percentage of white
border that is obstructed on
[[Page 29142]]
current stop arms. Agency staff looked at various models of stop arms
and concluded that, at most, 15 percent of the white border is
obstructed by mounting hardware. Therefore, S5.1.2 has been changed to
permit 15 percent obscuration of the white border.
G. Outlining Versus Centering the Lamps in the Legend
Transpec was the only commenter to address the issue of placement
of the lights in or around the legend. Its recommendation against
placement on the border of the legend was based on its desire to avoid
a ``Christmas tree effect'' it found in one of its prototypes. As
stated in NHTSA's November 1, 1995 interpretation letter to Specialty,
widely spaced lights ``could appear as a random field of lights (like a
Christmas tree), distracting the observer and resulting in diminished
readability.'' Transpec therefore recommends restricting light
placement to a location ``centered'' within the letters.
The agency notes that this ``Christmas tree effect'' is caused more
by excessive spacing between adjacent lights than by their placement
relative to the legend. The effect can also be caused by lights
centered in the legend's letters, if the spacing between the lights is
too great. Conversely, the effect can be avoided with lights placed
around the perimeter of the legend's letters if the lights are located
close enough together.
The option for placing the lamps around the border is being
retained in the final rule. The agency does not believe it is currently
necessary to regulate the spacing of the lights in or around the
legend. The optimum spacing might vary according to the lamp intensity,
lamp size, and legend letter size. NHTSA will monitor the products
being offered and will consider specifying light spacing if it finds
stop arms being produced with LEDs that impair the effectiveness the
stop arm, regardless of whether they are centered in, or arranged
around the border of, the letters.
H. Effective Date
Some commenters urged delaying the effective date. Specialty
recommended that the effective date of these amendments be delayed
until extensive testing is conducted, out of a concern that pushing
untested, potentially nonbeneficial technologies quickly to market
would not be in the interest of the general public. The NSTA, the
NASDPTS, Mr. Gough, and a few other commenters also encouraged NHTSA to
conduct extensive testing before promulgating the rule.
Other commenters, notably Transpec and some States and school
districts that liked Transpec's stop arm, urged an immediate effective
date. The primary reason given was that to delay implementation would
perpetuate confusion and ambiguity over Transpec's LED-equipped stop
arm and delay arrival of a beneficial technology in the market.
The agency concludes that an immediate effective date is warranted.
Field testing indicates that the Transpec stop arm is at least as
effective as existing stop arms in stopping motorists from illegally
passing stopped school buses. The commenters who encouraged more
extensive testing did not have the benefit of the results of the
Florida study and may not have realized the large number of smaller
pilot test programs being conducted by the other States and school
districts when they composed their comments. The agency considers this
field testing to be sufficient.
This amendment is permissive only, so there is no burden associated
with an immediate effective date. Since the LED-equipped stop arms seem
effective, there is no reason to delay their entry into the
marketplace.
I. Miscellaneous issues
There was no comment on several aspects of the proposal, and these
elements are maintained in the final rule. These include: (1) the
proposal to use a diminished ``net stroke width'' of the letters in the
legend to account for the width of the lights centered within them; (2)
the removal of the word ``filament'' in S6.2.2.1 to remove the
restriction against non-filament light sources; (3) the addition of the
words ``xenon short arc'' clarification that the requirements of
S6.2.2.2 apply only to that type of gaseous discharge lamp; and (4) the
addition of a requirement in S5.3.1.3 that the forward side of the
rearmost stop signal not be reflectorized if there are forward and
rearward stop arms.
Regulatory Analyses and Notices
A. Executive Order 12866 (Federal Regulation) and DOT Regulatory
Policies and Procedures
This notice was not reviewed under Executive Order 12866, because
the Office of Management and Budget determined that it is not
significant within the definitions of the Executive Order. NHTSA has
analyzed this rulemaking and determined that it is not significant
within the meaning of the Department of Transportation regulatory
policies and procedures. The agency has determined that the economic
effects of the amendment would be so minimal that a full regulatory
evaluation is not required. Since the amendment would impose no new
requirement but simply would allow for an alternative design, there are
no cost impacts. Because stop arms with legend lamps are optional, the
agency assumes those companies availing themselves of the option would
be maximizing benefits with respect to any added costs associated with
legend lamps.
B. Regulatory Flexibility Act
In accordance with the Regulatory Flexibility Act, NHTSA has
evaluated the effects of this rulemaking on small entities. Based on
this evaluation, I certify that the amendment will not have significant
economic impact on a substantial number of small entities. Accordingly,
a regulatory flexibility analysis has not been performed.
The following is NHTSA's statement providing the factual basis for
certification (5 U.S.C. 605(b)). Because Standard No. 131 applies to
vehicles rather than stop arms as items of motor vehicle equipment, the
rule applies primarily to school bus manufacturers. The school bus
industry is dominated by two companies that are not small entities, but
there are a few school bus manufacturers that are small entities. All
school buses are required to be equipped with stop arms. However, this
rule imposes no requirements, but merely allows school bus
manufacturers to have more choice in the stop arm designs they order.
The rule is thus beneficial to vehicle manufacturers, and has no
negative economic impact.
All stop arm manufacturers known to the agency are small entities.
They might be affected in the sense that market share might shift among
them if school bus manufacturers choose to purchase stop arms with
legend lights. Transpec is the only company known by the agency to
produce stop arms with legend lamps. However, NHTSA does not know if
Transpec's design will be widely accepted in the marketplace, either by
school bus manufacturers for installation on new buses, or in the
aftermarket. In addition, this rule provides flexibility for other
manufacturers to produce their own legend lamp-equipped stop arm
designs. Therefore, the agency does not view this rule as either
conferring a competitive advantage or imposing a negative impact on any
stop arm manufacturer.
C. Federalism Assessment
This action has been analyzed in accordance with the principles and
criteria contained in Executive Order
[[Page 29143]]
12612. NHTSA has determined that the rulemaking does not have
sufficient federalism implications to warrant the preparation of a
Federalism Assessment. This rule does not impose any unfunded mandates
on State, local, or tribal governments as defined by the Unfunded
Mandates Reform Act of 1995 (2 U.S.C. 1532-38).
D. Civil Justice Reform
This rule has no 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, Rubber and rubber
products, Tires.
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 571.131 is amended by revising S5.2.1, S5.2.2, S5.3.1,
S6.2.2.1, and S6.2.2.2, and by adding S5.3.1.1, S5.3.1.2, and S5.3.1.3
to read as follows:
Sec. 571.131 Standard No. 131, School Bus Pedestrian Safety Devices.
* * * * *
S5.2.1 The stop signal arm shall have a white border at least 12
mm (0.47 inches) wide on both sides, except as provided in S5.2.3.
Mounting brackets, clips, bolts, or other components necessary to the
mechanical or electrical operation of the stop signal arm may not
obscure more than 15 percent of the border on each side of the stop
arm. The portion of the border that may be obscured is in addition to
that portion which may be obscured by the two red lamps specified in
S5.3.2.
S.5.2.2 The stop signal arm shall have the word ``STOP'' displayed
in white upper-case letters on both sides, except as provided in
S5.2.3. The letters shall be at least 150 mm (5.9 inches) in height.
The letters shall have a stroke width of at least 20 mm (0.79 inches),
except as provided in S.5.3.1.1.
* * * * *
S5.3.1 Except as provided in S5.3.1.1, S5.3.1.2, or S5.3.1.3, the
entire surface of both sides of each stop signal arm shall be
reflectorized with Type III retroreflectorized material that meets the
minimum specific intensity requirements of S6.1 and Table I.
* * * * *
S.5.3.1.1 The legend of the retroreflective stop arm may be
illuminated in a manner such that light is emitted from the surface of
each letter or from the area immediately surrounding each letter. Only
red lamps may be used. They shall form the complete shape of each
letter of the legend, and shall be affixed to all letters (or to the
areas immediately surrounding all letters) in the legend. The shape of
each letter shall remain constant and, if the lamps are contained
within each letter, the net stroke width (stroke width minus the width
of the lamp(s)) of each letter of the legend, specified in S5.2.2,
shall not be less than 15 mm (0.59 inch). When the stop arm is
extended, the lamps shall flash at the rate specified in S6.2.2, with a
current ``on'' time specified in S6.2.2.1. All lamps shall be
positioned in one of the two following ways:
(1) centered within the stroke of each letter of the legend, or
(2) outlining each letter of the legend.
S5.3.1.2 Nonreflectorized mounting brackets, clips, bolts, or
other components necessary to the mechanical or electrical operation of
the stop signal arm shall not obscure more than 7.5 percent of the
total surface area of either side of the stop signal arm.
S5.3.1.3 When two stop signal arms are installed on a school bus,
the forward side of the rearmost stop signal arm shall not be
reflectorized.
* * * * *
S6.2.2.1 Lamps, except those subject to S6.2.2.2, shall have a
current ``on'' time of 30 to 75 percent of the total flash cycle. The
total current ``on'' time for the two terminals shall be between 90 and
110 percent of the total flash cycle.
S6.2.2.2 Xenon short-arc gaseous discharge lamps shall have an
``off'' time before each flash of at least 50 percent of the total
flash cycle.
* * * * *
Issued: May 22, 1998.
Ricardo Martinez,
Administrator.
[FR Doc. 98-14110 Filed 5-22-98; 3:07 pm]
BILLING CODE 4910-59-P
