Trailer Underride Protection - A Canadian Perspective

This paper provides details on the tests performed and the research findings of an underride guard test programme, including 10 full scale crashes using three types of deformable guards. The deformable guards tested included one meeting the minimum requirements of the NHTSA FMVSS 223 with ground clearances of either 560 or 480 mm, a second meeting the same minimum performance criteria with the addition of a device to limit the displacement of the horizontal member (ground clearance of 480 mm only) and a third being stiffer and designed to roughly maintain its 560 mm ground clearance during deformation. Crash tests were performed at speeds of 48, 56 and 65 kph.

The tests showed that an underride guard built to the minimum requirements currently specified in FMVSS 223, could not provide adequate protection to occupants in a compact or sub-compact vehicle; in our tests, such a guard failed to stop a 1998 Honda Civic CX striking the guard at 56 km/h, resulting in the failure of the neck of the ATD sitting in the driver and front passenger positions. The tests also showed that lowering the guard height, increasing the guard stiffness, or limiting the guard's displacement, will improve protection to the occupants of the colliding vehicle and reduce the risk of passenger compartment intrusion.