Federal Motor Vehicle Safety Standard (FMVSS) No. 223 specifies a test procedure for demonstrating that rear impact guards comply with the strength and energy absorption requirements of the standard. This procedure involves a quasi-static test in which the
horizontal member of the rear impact guard is slowly pushed for 125 mm, while the amount of resistance it offers is measured. Next, the guard is released and the amount of energy the guard absorbed is calculated.
The Truck Trailer Manufacturers Association (TTMA) submitted a petition for rulemaking requesting three changes to the test procedure. First, TTMA requested that we eliminate the lower bound of the range of acceptable rates of force application, so that the force can be applied in discrete start-stop steps. Second, TTMA requested that the requirement to displace the guard by a full 125 mm be eliminated if it appeared that the guard had met all requirements before that point. Third, TTMA suggested that the elastic rebound from guards that rebound very slowly following removal of the force not be subtracted from the calculated energy absorption. Each of the proposed revisions purports to ease the burden of testing on rear impact guard manufacturers, especially small businesses.
We are denying the petition. TTMA has not demonstrated a need for slower rates of force application. We have already lowered the permissible rate of force application to a level that is not burdensome, and even allow a manufacturer to specify, within a broad range, the force application rate on which it based its certification. Stopping the test before a displacement of 125 mm is not practical for compliance testing. Since we would have no way of knowing how far a guard would rebound, we could not know, in advance, how much energy the guard would absorb. We have answered TTMA's third request by providing an interpretation of the existing regulatory language.
Document Subtype:
Federal Register Publication
Received Date:
September 10 1999, at 12:00 AM Eastern Daylight Time
Page Count:
5
Comment Due Date:
September 10 1999, at 11:59 PM Eastern Standard Time
U.S. DOT/NHTSA - Denial of Petition for Rulemaking
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