The underride guard is the metal bumper that hangs from the back of a semitrailer. Its designed to stop a smaller vehicle from sliding beneath a high-riding trailer in a rear-impact crash, thus preserving survival space for the people inside the lower-riding vehicle. The IIHS Toughguard winners have rear guards that prevent underride of a midsize car in three test modes: full-width, 50% overlap, and 30% overlap. In each test, a midsize car travels at 35 mph toward a parked semitrailer.
Great Dane semi-trailer underride guard test photo"Our research told us that too many people die in crashes with large trucks because underride guards are too weak," said David Zuby, the Institute's executive vice president and chief research officer. "So we designed crash tests to replicate scenarios where guards have failed in real-world crashes. At first, only one of the semitrailers we evaluated passed all three tests the Manac. Now five trailers do. Manufacturers really took our findings to heart and voluntarily improved their guard designs."
The Toughguard award represents six years of IIHS research and testing, including evaluations of multiple trailers from eight of the largest trailer manufacturers in North America.
In several cases, IIHS reports, when a manufacturers underride guard failed the test, the makers reworked their designs and asked for retests. All the changes that manufacturers have made exceed current standards in place in the United States and Canada, as well as proposed new requirements from the National Highway Traffic Safety Administration (NHTSA) that would essentially align U.S. and Canadian underride regulations.
In 2015, 427 of the 2,646 passenger-vehicle occupants killed in large truck crashes died when the fronts of their vehicles struck the back of trucks can increase of 39% from 2011, when 260 of the 2,241 passenger-vehicle occupants killed in large truck crashes died in impacts with the rear of a large truck.