Interpretation ID: nht81-3.34

DATE: 11/10/81

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Truck Trailer Manufacturers Association

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of October 6, 1981, asking for our 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 the 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 typical front bulkhead is 8 to 9 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 the 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 frame 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,

Truck Trailer Manufacturers Association

October 6, 1981

Frank Berndt Chief Counsel National Highway Traffic Safety Administration

Subject: Interpretation of the Location of Front Clearance Lamps on Platform Trailers with Permanent Bulkheads

Dear Mr. Berndt: TTMA requests your concurrence that the location of 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.

Platform trailers are sold in three configurations: (1) without front bulkheads, (2) with removable front bulkheads, and (3) with permanent front bulkheads. Often platform trailers without front bulkheads will be built for stock and placed on a dealers lot. A customer may then purchase the new trailer and request that a bulkhead be added to the trailer. A customer may also bring to the dealer a used platform trailer and request that a permanent bulkhead be welded to the trailer.

The structural framing of the front bulkhead would require that the front clearance lamps, if mounted on the front bulkhead, be located about 8 inches inboard of the front corner of main frame location used for clearance lamps on platform trailers without front bulkheads.

Table II of FMVSS 108 states that the purpose of the front clearance light is to indicate the overall width of the vehicle. NHTSA by interpretation (letter of 2/5/74 to Evan Hammond, Trailmobile) has stated that the primary purpose of these lamps is to indicate the overall width of the vehicle and the secondary purpose is to indicate the overall height. Front bulkheads typically range in height from 48 to 60 inches (4 to 5 ft.), placing the top of the bulkhead about 100 to 112 inches (8 to 9 ft.) above the ground. The identification lamps on the truck tractor are typically 118 inches (10 ft.) above the ground.

The side view mirror of a truck tractor is typically mounted about 85 inches (7 ft.) above the ground. Due to the frame around the front bulkhead of the platform trailer, the front clearance lamp would be located about 12 inches (1 ft.) below the top of the bulkhead or 88 inches (7 ft.) above the ground. This location results in the lamp shining into the driver's eyes by way of the side view mirror.

An examination of platforms with permanent bulkheads reveals that drivers remove the bulbs from the clearance lamps or place tape over the lamps. TTMA contends that a location which results in the lamp shining into the driver's eyes is not a practical location and may indeed result in a safety hazard.

Some bulkheads are made with the provision for fastening a tarpaulin. NHTSA, in an interpretation regarding tarps on bulk commodity trailers (letter of 5/2/69 to K. L. Mathews, Reliance Trailer & Truck Company), stated that the clearance lamps should be mounted as high as practical to clear the bottom edge of the tarp. It is assumed that this interpretation would also apply to the location of clearance lamps on platform trailer front bulkheads. The need for attaching tarpaulins results in the clearance lamps being located as much as 30 inches below the top of the bulkhead or about 70 inches (6 ft.) above the ground.

NHTSA has issued an interpretation of S4.3.1 of FMVSS 108 (letter of 3/22/74 to TTMA) stating that front clearance lamps may be mounted on the lower front rail of platform trailers with removable front bulkheads. Since a removable front bulkhead looks similar to a permanent bulkhead and serves the same function, it is TTMA's contention that they be treated similarly with regard to location of front clearance lamps. This interpretation follows the reasoning used by NHTSA (letter of 3/10/81 to TTMA) that the function of a permanent dolly and its towbar are identical in function with that of a converter dolly and its towbar and there is no reason to distinguish one from the other for purpose of computation of overall length and the requirement for an intermediate side marker lamp.

TTMA concludes that the front clearance lamps on platform trailers with and without front bulkheads should be located at the corner of the frame rail to satisfy the requirement that the lamp indicate the trailer's overall width, that this is as high as is practical since a higher location would create a safety hazard for the driver, and that a permanent bulkhead serves the same function as a demountable bulkhead which is exempted from a clearance lamp height requirement.

Donald W. Vierimaa Director of Engineering

(Graphics omitted)

(Graphics omitted)