Interpretation ID: aiam3283
Vice President
Safety and Security Consultants
702 Candy Mountain road
Birmingham
AL 35217;
Dear Mr. Hitt: This is in reply to your letters of April 11, and April 25, 1980 respectively to this agency and to Mr. Vinson of this office, (sic) These letters reference requirements for side marker reflectors and clearance lamps for trailers used to carry agricultural products over the public roads.; You say that your trailers travel 'as much as several hundred miles o the highways at all hours of the day and night'. Therefore, they are 'motor vehicles' subject to all applicable Federal Motor Vehicle Safety Standards.; I enclose a copy of Federal Motor Vehicle Safety Standard No. 10 (Title 49, Code of Federal Regulations, section 571.108). You will see that marker lamps and reflectors are required on all trailers, while rear clearance lamps need be added only if the overall width of a trailer is 80 inches or more. A clearance lamp facing to the rear may be combined with a rear side marker lamp, we assume that is what you mean by a 'side clearance lamp' as the standard speaks only in terms of 'front' and 'rear' clearance lamps.; You have also asked for the 'early history' of why these lamps ar required pursuant to 'Regulation No. 393.15.' As a matter of clarification that section of Title 49 is enforced by a different agency, the Bureau of Motor Carrier Safety Federal Highway Administration, and covers lighting equipment required for commercial vehicles being used in interstate commerce. Our lighting standard, essentially identical, must be met before the vehicle is used, i.e., from time of manufacture until time of sale. To answer your question, clearance lamps must indicate the overall width of the trailer, in order that other drivers may be alerted to the presence on the road of a large vehicle. Side markers help identify the presence of a vehicle whose head lamps or taillamps may not be seen by a driver approaching it from a 90 degree angle, such as at an intersection.; Sincerely, Frank Berndt, Chief Counsel