Interpretation ID: nht94-4.51

TYPE: INTERPRETATION-NHTSA

DATE: October 14, 1994

FROM: Recht, R. Philip -- Chief Counsel, NHTSA

TO: Larson, Victor P. E. -- Cryenco, Inc. (COLORADO)

TITLE: NONE

ATTACHMT: Attached To A Letter Dated 5/17/94 From Victor Larson To John Womack (OCC 9984)

TEXT: This responds to your FAX of May 17, 1994, with reference to the application of conspicuity material to the sides of cryogenic tank trailers.

You point out that the only side mounting surface for striping that is perpendicular to the road is at the center of the tank, approximately 90 inches above the road surface. You ask for confirmation of your interpretation that conspicuity material can be placed at this location "if that is the only available mounting area" and that it is not necessary to add additional structure for the sole purpose of providing a lower vertical mounting surface.

We confirm your understanding. Standard No. 108 specified an original mounting height for conspicuity material as close as practicable to 1.25 m. However, in a notice published on October 6, 1993, NHTSA amended the requirement to "as close as practicab le to not less than 375 mm and not more than 1525 mm above the road surface." The practicability qualification allows manufacturers to choose a location for conspicuity treatment that is outside the specified range to avoid body modifications that might otherwise be required to mount the material within the specified range.

The manufacturers of conspicuity material certify its performance in a vertical plane. Trailer manufacturers should mount the material in a vertical plane or as close to a vertical plane as the trailer shape offers, in order to achieve the full conspicu ity benefits of the material. In the case of your tank trailer without a suitable vertical surface below the belt line of the tank, reflective material at a belt line that is 90 inches above the road surface would be considered to have been mounted as c lose as practicable to the upper specification of the height range (1.525 m). As NHTSA observed when it adopted the original mounting height specification with its practicability provision, flexibility in the vertical location of conspicuity material is necessary for compliance of some tank trailers. However, it should not be overlooked that other types of tank trailers may have vertical surfaces on the frame, fenders, or other equipment well suited for conspicuity material.

You inform us that some trailers have rear and midship cabinets that could be used, in conjunction with the belt line location, to provide a location for striping, although this would result in a non-aligned striping pattern. With respect to trailers eq uipped with cabinets, you asked whether compliance would be satisfied if only the belt-line location is used. The answer is yes, provided that the requirement of paragraph S5.7.1.4.2(a) is met, i.e., which provides that "the strip need not be continuous as long as not less than half of the length of the trailer is covered and the spaces are distributed as evenly as practicable." Since the strip need not be continuous, this would allow discontinuities in a strip mounted at 90 inches in which the cabinet s were not used.

Your final question is the required orientation of striping for conspicuity; some of your customers have requested placement of material at a downward angle of approximately 30 degrees to accommodate their graphics better. The standard does not explicit ly address the issue of orientation. However, as noted in response to your first question, trailer manufacturers should mount conspicuity material in a vertical plane, or as nearly thereto as the trailer shape allows, so that the full conspicuity benefi ts of the material may be realized. If there is no available vertical surface on which the material can be mounted, we urge that a wider stripe of conspicuity material be used to provide the minimum required performance at the installed downward angle. The manufacturer of the conspicuity material which you use should be able to determine whether an increase in the width of the striping would allow the material mounted at or near the downward angle that your customer prefers to provide performance comp arable to a narrower strip mounted in a vertical plane.