Interpretation ID: 9217
Engineering Department
Travis Body and Trailer, Inc.
13995 F.M. 529
Houston, TX 77041
Dear Mr. Backs:
We have received your FAX of October 19, 1993, to Taylor Vinson of this Office, asking for an interpretation of the trailer conspicuity requirements of Federal Motor Vehicle Safety Standard No. 108 as it applies to a dump trailer manufactured by your company.
With respect to the location of the horizontal side conspicuity treatment, you prefer not to place it on the rubrail because "our present extrusions have raised ridges on the outer surface." You propose to apply the conspicuity treatment between each side stake, resulting in 58% coverage of the trailer side. The tape is "in full view" from a point perpendicular to the side of the trailer, but at approximately 30 degrees from perpendicular, the edge of the tape begins to be obstructed by the side stake. You ask for our concurrence that your proposed treatment is in accordance with Standard No. 108.
We are pleased to provide our concurrence. The mounting height requirements of Paragraph S5.7.1.4.2 are specified in terms of practicability. The rule was amended on October 6, 1993, to specify a mounting height of "as close as practicable to not less than 375 mm and not more than 1525 mm above the road surface." The determination of practicability, in the first instance, is that of the manufacturer certifying compliance with Standard No. 108. NHTSA will not question that determination unless it appears clearly erroneous. Because of raised ridges, you deem the rubrail not as practicable a location as the slightly higher area. Paragraph S5.7.1.4.2 allows discontinuities in the side treatment as long as not less than half the side is covered and the spaces are distributed as evenly as practicable.
Although the sheeting itself must meet the performance indicated at the observation angles specified in Figure 29, there are no visibility requirements that apply to it once it is installed on a trailer. This mean that the obscuring of the conspicuity treatment that begins at about 30 degrees from perpendicular under your proposed treatment is not prohibited by Standard No. 108.
Sincerely,
John Womack Acting Chief Counsel
ref:108 d:11/18/93