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Interpretation ID: 24516.ztv

Mr. James A. Haigh
Vice President of Manufacturing
Transpec Worldwide
7205 Sterling Ponds Court
Sterling Heights, MI 48312

Dear Mr. Haigh:

This is in reply to your letter of May 28, 2002, addressed to John Womack of this Office. You related that Transpec has developed an LED sign that mounts on the rear of a school bus. The device is wired into the eight-lamp school bus warning lamp system. When the amber lamps of the system are activated, the LED sign alternately flashes "Caution-Stopping." When the red lamps of the system are activated, the sign flashes "Stop" or "Do not Pass" (the photograph you enclosed depicts this mode of the device as it operates). You also related that you have searched both Federal Motor Vehicle Safety Standards (FMVSS) Nos. 108 and 131, and have found nothing in either that would prohibit use of your device. You asked for confirmation of your findings.

Your letter did not relate whether your device will be installed by a school bus manufacturer as part of the vehicles original lighting package, or purchased by school districts to be installed on buses already procured. Generally, we allow local school bus jurisdictions to exercise considerable discretion in prescribing lighting specifications that they deem desirable for their vehicles under local conditions. Further, even if the installation of a supplementary lighting device on vehicles in use might be prohibited by Federal law, the prohibition is nullified if the installation is performed by the owner of the vehicle (e.g., if the modification of the school bus is performed in the school districts own repair shops). Thus, our general answer to your question is that your device is not prohibited under Federal law.

However, we think it important to explain to you our views on electronic message boards and school bus lighting. The eight-lamp school bus warning system you reference is a required lighting system under S5.1.4 of FMVSS No. 108 (as an alternative to a four-lamp system). Paragraph S5.1.3 prohibits the addition of lighting equipment not required by FMVSS 108 (or any other motor vehicle equipment), prior to a vehicles initial sale, if it impairs the effectiveness of lighting equipment required by FMVSS 108. The issue of whether lighted messages have an impairing effect has been the subject of frequent interpretations from this Office. For a comprehensive understanding of the issue, you may access these interpretations on the National Highway Traffic Safety Administrations website,, using the search word "message." I am enclosing two representative letters, one of mid-1995 to K. Howard Sharp and the other, dated August 4, 1997, to Alan Robinson. The letter to Mr. Sharp indicates that message-board interpretations as late as 1995 had been "cautionary in tone, rather than prohibitive." The later letter to Mr. Robinson flatly states that "electronic message boards are not permitted on motor vehicles that have been manufactured to conform to Standard No. 108." However, we are willing to make an exception in those instances where school districts have concluded that, under local conditions, an electronic message board with the messages that you described would enhance the safety of school bus passengers.

We informed Mr. Sharp that "there is less possibility of impairment existing if the message visible to a following driver is related to the lamp function that occurs simultaneously." In the case of your device, "Caution-Stopping" appears simultaneously with the flashing of the amber lamps which are generally used with the stop lamps to indicate the school bus is stopping. The messages of "Stop" and "Do not Pass," appear only when the red lamps are flashing and the school bus is stopped. Thus, we do not see that the device you describe would create an impairment within the meaning of S5.1.3.

Although FMVSS No. 131 "establishes requirements for devices that can be installed on school buses to improve the safety of pedestrians in the vicinity of stopped school buses," (paragraph S1), in fact only one such device has been specified, the stop arm. You are correct that nothing in FMVSS No. 131 would prohibit the installation of your LED sign.

Jacqueline Glassman
Chief Counsel