Interpretation ID: aiam3481
Director of Engineering
Truck Trailer Manufacturers Association
2430 Pennsylvania Avenue
N.W.
Washington
DC 20037;
Dear Mr. Vierimaa: This is in reply to your letter of October 6, 1981, asking for ou concurrence that front clearance lamps 'located at the frame level (about 50 inches above the ground) on platform trailers with permanent front bulkheads conforms with FMVSS 108.'; Clearance lamps are required by Standard No. 108 'to indicate th overall width' of a vehicle, and to be 'as near the top thereof as practicable.' As you noted, NHTSA has commented before that the indication of overall width is the primary function of clearance lamps, with a secondary purpose of indicating overall height. However, because trailers are not required to have identification lamps on their front, the secondary purpose of clearance lamps on trailers is important, especially if the top of the trailer is substantially higher than that of the truck tractor towing it.; You have stated that the top of the trailer is substantially highe than that of the truck tractor towing it.; You have stated that the top of the typical front bulkhead is 8 to feet above the ground, and the identification lamps of truck tractors are typically 10 feet above the ground. We will assume also that the tractor's clearance lamps are also typically 10 feet above the ground. You have also stated that the mounting height of truck tractor rear view mirrors and bulkhead-mounted clearance lamps are essentially the same, and that as a result 'drivers remove the bulb from the clearance lamps or place tape over the lamps.'; The determination of practicability is one that is made by th manufacturer of the trailer. NHTSA will accept a determination that mounting of clearance lamps at the top of the bulkhead is not practicable if such lamps are reflected into the driver's eyes by way of the side view mirror. But if the configuration of a trailer with a permanent front bulkhead is such that the clearance lamps may be located at the top of the bulkhead from without interfering with the vision of the truck tractor's operator, that location would appear to be 'practicable' within the meaning of Standard No. 108 and the situation your letter addresses.; Sincerely, Frank Berndt, Chief Counsel