Interpretation ID: nht79-2.49

DATE: 01/09/79

FROM: AUTHOR UNAVAILABLE; J. J. Levin, Jr.; NHTSA

TO: SAE Lighting Committee

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of December 18, 1978, asking for an interpretation of Federal Motor Vehicle Safety Standard No. 108.

The standard was recently amended to establish a ceiling of 60 inches from the roadway surface for the mounting height of rear side marker lamps. You have asked whether it is permissible to mount an additional side marker lamp at the upper rear corner of a trailer whose overall height exceeds 60 inches.

The answer is yes. Such a supplemental lamp would not appear to impair the effectiveness of lighting equipment required by Standard No. 108, within the meaning of the prohibition of S4.1.3 that you mentioned.

SINCERELY,

COMMITTEE CORRESPONDENCE

December 18, 1978

National Highway Traffic Safety Agency

Attn: Office of Chief Council

SUBJECT: Docket No. MC-66-1; Amendment No. 77-8

Gentlemen:

The DOT/FHWA/BMCS recently announced a new rulemaking notice which required that large semi-trailers and full trailers have their rear side marker lamps located at a height between 15 inches and 60 inches above the road surface. This is the so-called tracking light to enable drivers to have better visibility of the rear section of the trailer in bad weather.

The specific question raised here is whether or not trailer manufacturers and users can continue to mount a side marker lamp at the upper rear corners of the trailers on the sides of the vehicles in addition to the newly required device at the lower mounting dimensions just described above.

Past precedent would indicate that having an additional, optional side marker lamp at the top rear corners would certainly not, in any way, interfere with the required lighting. However, we are getting inquiries as to whether or not this is permissable and I would like your confirmation that this presents no problem in using this added, optional light.

Apparently, some manufacturers and vehicle users prefer to use a rear side marker lamp at both the top and bottom which would undoubtedly increase the safety. We would appreciate your prompt response so that we can in turn reply to these inquiries.

Paul G. Scully Chairman, SAE Lighting Committee

P.S. The NHTSA final rule was published 31 August 1978 as Docket No. 77-1;