J. Adam Krugh IV
3912 West 73rd Terrace
Shawnee Mission, KS 66208
Dear Mr. Krugh:
This responds to your request for an interpretation of how the National Highway Traffic Safety Administrations (NHTSAs) regulations apply to a device you have invented, a red lamp to be placed on school bus roofs, that you believe would enhance safety for children getting on and off school buses. Our answer is provided below.
You write that your device, the ALLSTOP, is "designed to overcome the line of sight problems created by todays taller vehicles and wider roadways." You believe that with the ALLSTOP, other drivers in all directions of the bus will have adequate visible warning that the bus is loading or unloading children. A brochure accompanying your letter depicts the ALLSTOP as a red lamp attached to a metal rod in the middle of the school bus roof that stands upright perpendicular to the roof.
In a telephone conversation with Dorothy Nakama of my staff, you stated that the ALLSTOP would only stand upright when the school bus door is open. When upright, the device would flash, similar to a "police light" with a rotating halogen lamp, or would flash by a red LED strobe light. At all other times (i.e., when the door is closed and the school bus is in motion), the ALLSTOP is not illuminated and lies flat, parallel to the school bus roof. You state that a motorized base moves the ALLSTOP up and down. You further state that the device can be manually overridden by the school bus driver to not deploy. You state that details about the ALLSTOP, such as the length of the metal rod, the type of lamp used in the device, and its flash rate, are yet to be finalized. You also stated that it is your hope that the ALLSTOP, a patented product, will be used on both new school buses and as aftermarket equipment on school buses that are already owned by schools and school districts.
By way of background information, NHTSA is authorized to issue Federal Motor Vehicle Safety Standards (FMVSSs) applicable to new motor vehicles and new items of motor vehicle equipment. NHTSA has used this authority to issue Standard No. 108, Lamps, reflective devices, and associated equipment. This agency does not provide approvals of motor vehicles or motor vehicle equipment, nor do we endorse any commercial products. Instead, manufacturers are required to certify that their vehicles and equipment meet applicable standards. Also, it is unlawful for dealers to sell motor vehicles or motor vehicle equipment that do not meet applicable standards.
Under Standard No. 108, non-standard lighting devices are prohibited on new vehicles if they impair the effectiveness of lighting devices required by Standard No. 108. See S5.1.3. It is our opinion that a device such as the ALLSTOP would impair the effectiveness of the required equipment.
S5.1.4 of Standard No. 108 requires school buses to be equipped with a system of four red signal lamps, or four red and four amber signal lamps, designed to meet SAE Standard J887 School Bus Red Signal Lamps, July 1964, and installed at the top and evenly spaced from the vertical centerline of the bus. These lamps must flash alternately at a rate of 60-120 cycles per minute.
As we have said before, traffic safety is enhanced by the familiarity of drivers with established lighting schemes, which facilitates their ability to instantly and unhesitatingly recognize the meaning lamps convey and respond to them. The required school bus signal lamp system provides an important and standardized message. It is our opinion that the addition of a novel signal lamp such as the ALLSTOP that rises from the middle of the school bus roof at the same time as the school bus signal lamp system activates would divert a driver's attention from the required signal lamps and cause confusion with respect to their meaning, and thereby impair the effectiveness of the required lamps.  , 
With respect to the aftermarket, 49 U.S.C. 30122 has the effect of requiring that the installation of any aftermarket vehicle lamp, by a manufacturer, distributor, dealer, or motor vehicle repair business, must not "make inoperative" any element of design or device installed on a vehicle in accordance with Standard No. 108. As with original equipment, we regard the addition of a novel signal lamp such as the ALLSTOP to make inoperative a vehicle's original required lighting equipment by diverting a driver's attention from the required signal lamps, and causing confusion with respect to their meaning.
Modifications made by a school bus owner itself are not prohibited by our statute. However, we urge owners not to degrade the safety of their vehicles.
I hope this information is helpful. If you have any further questions about lighting issues, please contact Mr. Taylor Vinson. Questions about school bus issues may be addressed to Ms. Dorothy Nakama. Both attorneys may be reached at this address or at (202) 366-2992.
 We note that Standard No. 131 requires school buses to be equipped with a stop signal arm on the left side of the bus. This required device also provides a standardized message to drivers.
 Our opinion is not affected by whether a device such as the ALLSTOP would flash or not. I note, however, that Standard No. 108 only permits certain types of lamps to flash.