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Interpretation ID: GF000843.2

    Mr. Robert S. Livingston
    Stewart & Stevenson Tactical Vehicle Systems
    PO Box 330
    Sealy, TX 77474


    Dear Mr. Livingston:

    This responds to your January 27, 2005, e-mail regarding lamp, reflex reflector, and conspicuity system requirements for trailers. First, you ask whether the rear side marker lamp, the rear clearance lamp, and the reflex reflector can be combined into a single lighting device so long as it is "visible from both vehicle axes. " Second, you ask whether the retroreflective sheeting located at the rear of the trailer can be combined with the retroreflective sheeting located on the underride guard. You provided a photograph of the prototype vehicle and indicated that its gross vehicle weight rating (GVWR) is over 10,000 pounds. Our answers follow.

    By way of background, the National Highway Traffic Safety Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under 49 U.S.C. Chapter 301, manufacturers are required to certify that their vehicles and equipment meet applicable requirements.

    The Federal standard applicable to lighting equipment on trailers and other motor vehicles is Federal motor vehicle safety standard (FMVSS) No. 108, Lamps, reflective devices, and associated equipment. S5.4 of FMVSS No. 108 permits combining certain items of lighting equipment if the requirements for each item are met. Based on the language of this section, you ask two questions regarding combining lamps, reflex reflectors, and retroreflective sheeting on trailers.

    Combining Lighting Devices

    Tables I & II specify that each trailer must be equipped with, among other things:

    1. 2 red clearance lamps located at the rear outboard edges of the trailer as near the top as practicable.

    2. 2 red side marker lamps, located on the sides of the trailer, as far to the rear as practicable.

    3. 4 red reflex reflectors. 2 located at the rear outboard edges of the trailer as far apart as practicable. 2 located on the sides of the trailer, as far to the rear as practicable.

    You ask if these requirements can be met by single lighting devices at each rear corner of the trailer. The photograph accompanying your e-mail shows a lamp and a reflex reflector tilted at a (approximately) 45-degree angle on each rear corner of the trailer.

    With respect to reflex reflectors, S5.7 of FMVSS No. 108 requires that your trailer be equipped with a conspicuity system. Further, S5.1.1.29 specifies that a trailer equipped with a conspicuity system in conformance with S5.7 need not be equipped with the reflex reflectors required by Table I, if the conspicuity material is placed at the locations required for the Table I reflectors. Thus, if your trailer is equipped with conspicuity material at the appropriate locations specified above, you may omit installing reflex reflectors on this trailer.

    With respect to side marker and clearance lamps, S5.4 discussed above allows these lamps to be combined, if the photometric requirements for each lamp are met, as installed on the vehicle. SAE Standard J592e "Clearance, Side Marker, and Identification Lamps," July 1972, specifies that both side marker and clearance lamps meet the minimum photometric requirements (expressed in candela) at test points located 45 degrees to the left and right of each lamp. We are familiar with combination lamps that emit a photometric output over 180-degrees wide in order to simultaneously satisfy the photometric requirements for side marker and rear clearance lamps. This is because the angle between the furthest forward test point of the side marker lamp and the furthest inboard test point of the rear clearance lamp is 180-degrees.

    We examined the photograph of the prototype trailer and question whether your lamp could simultaneously meet the applicable photometric requirements of J592e for both a clearance and side marker lamp because it does not appear to be a combination lamp capable of emitting light over a 180-degree angle. We suggest you contact the lamp manufacturer to determine whether the proposed combination lamp would be capable of complying with all the applicable requirements as installed on your trailer.

    Combining Retroreflective Sheeting

    Table I specifies that each trailer must be equipped with, among other things, a conspicuity system meeting the requirements of S5.7 of FMVSS No. 108. In particular, S5.7.1.4.1 requires 3 elements of retroreflective sheeting at the rear of each trailer. Element 1 must be located at the bottom, horizontally across the full width of the trailer. Element 2, consisting of two pairs of white strips of sheeting, must be located horizontally and vertically at the upper contours of the body. Element 3 must be located horizontally across the full width of the rear underride guard. You ask if Element 1 and Element 3 retroreflective sheeting could be combined into one retroreflective sheet located on the underride guard.

    Our answer is no. S5.4 does not apply to your second question because trailers equipped with underride guards must have separate retroreflective sheeting on the underride guard, and on the rear at the bottom of the trailer. Thus, the retroreflective sheet

    located on the underride guard cannot satisfy the location requirements for Element 1 retroreflective sheeting, which must be located on the trailer, above the underride guard. Accordingly, your trailer must have Elements 1 and 3 retroreflective sheeting to comply with the requirements of S5.7.1.4.1. We are enclosing Figures 30-1, and 30-2 to clarify this issue.

We note that the picture of your prototype trailer appears to be missing Element 2 retroreflective sheeting. Your trailer must also, be equipped with Element 2 retroreflective sheeting.

I hope you find this information helpful. If you need further assistance, please contact George Feygin of my staff at this address or at (202) 366-2992.

Sincerely,

Jacqueline Glassman
Chief Counsel

Enclosure
ref:108
d.5/3/05