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10-007285 S5-1-4 William H Thompson III 108 School Bus Lighting Interp Letter








William H. Thompson III

146 N. 58 Street

Philadelphia, PA 19139


Dear Mr. Thompson:


This letter responds to your request dated October 23, 2010 requesting an interpretation of Federal motor vehicle safety standard (FMVSS) No. 108, Lamps, Reflective Devices, and Associated Equipment as it relates to your invention. We believe that your invention, which alters the sequence in which school bus signal lamps will flash, does not meet the requirements of FMVSS No. 108 for the reasons that follow.


In your request, you described the operation of your invention as containing four modes. The first mode is an idle mode where no lamps are flashing. The second mode operates to flash the amber school bus lamps. The third mode flashes one side red and the other side amber then flashes the complement. This mode repeats for approximately three seconds. Finally, the fourth mode flashes only the red lamps when the school bus door is opened and the entire system returns to idle when the bus door is closed. In your telephone conversation with Jesse Chang of my staff on April 11, 2011, you further clarified that the fourth mode would automatically open the school bus door if the school bus is equipped with an automatic door and that the fourth mode would signal the driver to open the door if the school bus is equipped with a manual door. It seems that your inventions alteration of the standard lighting scheme described in FMVSS No. 108 subpart S5.1.4 would likely detract from the standard message intended to be conveyed by school signal bus lamps. Thus, we believe your invention would be prohibited under both S5.1.3 disallowing additional lighting equipment which impairs the operation of required equipment, and the make-inoperative provisions of the Motor Vehicle Safety Act.


By way of background, the National Highway Traffic Safety Administration (NHTSA) is authorized to issue Federal Motor Vehicle Safety Standards that apply to both new motor vehicles and new items of motor vehicle equipment. NHTSA used this authority to promulgate FMVSS No. 108, which is the subject of your inquiry. While NHTSA is responsible for establishing safety standards, this agency does not provide approvals of motor vehicles or new items of motor vehicle equipment. Instead, manufacturers are required to certify that their vehicles and equipment meet the applicable standards and it is unlawful for dealers to sell motor vehicles or equipment not in compliance with these standards.


You are correct to refer to FMVSS No. 108 subpart S5.1.4 as the applicable regulation on school bus signal lamps. That standard requires each school bus to be equipped with either the four-lamp, all red lighting system described in subpart S5.1.4(a), or the eight-lamp, four red/four amber lighting system described in subpart S5.1.4(b). Subpart S5.1.4(b)(ii) further requires (in the eight-lamp setup) that the four amber lamps only be activated manually, that the four amber lamps automatically deactivate when the bus door is opened, and that the four red lamps automatically activate when the bus door is opened.


Additional lighting equipment is not generally prohibited under the FMVSS No. 108. However, there are two restrictions of interest that limit the permissible additions to the required lighting system under FMVSS No. 108 subpart S5.1.4. The first is S5.1.3 which limits the permissible additions that manufacturers and dealers may make before the first sale by stating that no additional lamp, reflective device or other motor vehicle equipment shall be installed that impairs the effectiveness of lighting equipment required by this standard. Through our prior interpretation letter to Steele Enterprises (December 6, 1999), we interpreted S5.1.3 to include under the definition of additional lamp the alteration of required lamps to perform in a manner different from the original design.[1] Further, our agency issued an interpretation letter dated December 11, 1995 and addressed to Ms. Carrie Stabile covering the subject of what constitutes impairment under S5.1.3. In that letter, we clarified the definition of impairment by stating that under S5.1.3, additional equipment cannot detract from the message that the required lamp is intended to impart.[2]


While your invention does not seek to include additional lamps, it is clear from our previous interpretations that altering standard lamps to perform non-standard functions is covered under the prohibition in subpart S5.1.3. Thus, the installation of your invention before the first sale of the vehicle would be governed by subpart S5.1.3. The amber and red lamps are intended to convey distinct messages to the other drivers on the road. The amber lamps indicate to drivers that the school bus is slowing down in preparation of making a stop. Then the red lamps indicate to drivers that the school bus has stopped and is loading or offloading students. As driver familiarity with established lighting standards is essential to preserving the intended message of the required lamps, we believe that your inventions addition of the third-mode lighting stage would impair the effectiveness of the required school bus signal lamps. Drivers familiar with the distinct bus slowing down and bus stopped messages conveyed by the amber and red lamps may not understand an intermediate lighting stage which combines both of these signal lamps. Thus, we believe your invention would be prohibited by FMVSS No. 108 if installed before the first sale.


The second restriction that limits the permissible additions to the required lighting system governs modifications to the vehicle after the first sale. After the first sale, the Motor Vehicle Safety Act of 1966 prohibits any manufacturer, distributor, dealer, or motor vehicle repair business from knowingly mak[ing] inoperative any part of a device or element of design installed on or in a motor vehicle or motor vehicle equipment in compliance with an applicable motor vehicle safety standard.[3] In this situation, we have expressed the interpretation that if new equipment or modifications interfere with the standard message that a lighting system is intended to convey, it constitutes rendering the required lighting inoperative. In our interpretation letter to Consumer Imports, LLC (December 6, 2002), we clarified this position by stating that the addition of a flashing stop lamp to the motorcyclists helmet would cause confusion and render the required stop lamp partially inoperative within the meaning of [the Motor Vehicle Safety Act].[4]


Under this second restriction, manufacturers, distributors, dealers, or motor vehicle repair businesses would also be prohibited by FMVSS No. 108 from modifying any buses currently in compliance with FMVSS to utilize your invention. For the same reason that the different flashing sequence would impair the effectiveness of the required school bus signal lamps, it would also render the lamps partially inoperative within the meaning of the Motor Vehicle Safety Act.


We thank you for your interest in improving safety for school children riding in school buses and the surrounding road users. If you have any further questions, please contact Jesse Chang (202-366-2992) of this office.







O. Kevin Vincent,

Chief Counsel


Ref: FMVSS No. 108