The Insurance Institute for Highway Safety (IIHS) recently conducted tests on the underride guards of most big rig trailers, finding that in crashes involving only a small portion of the truck’s rear, most trailers failed to prevent potentially deadly underride.
The underride guards, the steel bars hanging from the backs of trailers, are made to prevent the front of a passenger vehicle from moving underneath the rig in the event of a crash. The crash tests show however that these guards don’t hold up well in crashes that occur on the outer edges of the trailers.
IIHS engineers put trailers from the world’s eight largest manufacturers and all of the trailers had underride guards that met both U.S. and Canadian standards. In each crash test, a Chevrolet Malibu was used to strike a parked truck at 35 mph. The first test conducted had the vehicle crashing at the center of the trailer, and all eight of them prevented underride.
However, in the second test, where only half of the vehicle overlapped with the trailer, only one of the eight passed. When the overlap was reduced to 30 percent, all but one trailer passed the test.
The eight trailers involved in the test were from: Great Dane, Hyundai, Manac, Stoughton, Strick, Utility, Vangard, and Wabash. Vanguard was the only trailer to fail on the 50-percent overlap test, while Manac was the only one to pass the 30-percent overlap test.
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