Interpretation ID: nht94-3.17

TYPE: INTERPRETATION-NHTSA

DATE: June 1, 1994

FROM: Donald W. Vierimaa -- Vice President-Engineering Truck Trailer Manufacturers Association

TO: John Womack -- Acting Chief Counsel, NHTSA

TITLE: NONE

ATTACHMT: Attached to a letter dated 7/14/94 from John Womack to Donald W. Vierimaa (A42; STD 108)

TEXT: We request an interpretation of S5.7.1.4.1(c) of FMVSS 108 which requires "A strip of sheeting in alternating colors across the full width of the horizontal member of the rear underride protection device. Grade DOT C2 material not less than 38 mm wide m ay be used." and S5.7.1.4.1 which states in part, "Element 3 is not required for trailers without underride protection devices."

NHTSA has not issued a final rule on rear impact guards and protection (rear underride guards) and even when it is issued, it is not likely to become effective until two years later. However, in the meantime, we published on April 1, 1994 TTMA Recomm ended Practice No. 92, "Rear Impact Guard and Protection," which closely resembles the NHTSA proposed rule. Does the term "underride protection device" as you have used it in FMVSS 108 only include the device yet to be required by NHTSA or would it incl ude the device described in TTMA RP No. 92?

2

TTMA RP No. 92 recommends in section 5.1.4 that "The vertical dimension of the guard's horizontal member shall not be less than 4 inches (101.5 mm)." Some trailer manufacturers are installing on refuse and chip trailers guards with round cross section s and square at 45 degrees (diamond) cross sections (see sketch) to shed any debris which may fall on the guard. In addition, some trailers are restrained by a curved hook which grabs and holds the round cross section guard while trash is loaded into th e trailer. If a 38 mm retroreflective strip of sheeting is applied to these guards, will such installations comply with FMVSS 108?