New Crash Tests Reveal Underride Guards on Big Rigs Put Passenger Vehicle Drivers at Risk

A new study published by the Insurance Institute for Highway Safety found that while most semitrailers are doing their part in trying to keep cars from sliding underneath them during a crash, most of them fail to prevent deadly underride.

Underride crashes occur when a vehicle collides with the rear or side of a semi-truck trailer. The force of impact during the crash as well as the weight of the trailer have the capability to crush or shear off the roof of a car. When the occupant compartment is crushed, safety apparatuses like airbags and seat belts tend to fail. Individuals involved in these types of accidents usually suffer serious and often fatal head and torso injuries, as well as decapitation.

Most modern semitrailers are required to have underride guards (steel bars that hang below the back of trailers) to prevent vehicles from sliding beneath them. Their purpose is to ultimately decrease the amount of vehicular damage and increase the chances of survival during an accident. Many tractor trailer manufacturers now produce trailers with underride guards that are stronger and larger than what is required by law, to maximize their effectiveness in the event of an accident.

Crash tests conducted by the IIHS revealed that underride guards generally work well to prevent underride, however they are less effective during collisions with outer edges of trailers. In their recent study, IIHS researchers put trailers from eight of the top trailer manufacturers through a series of progressive crash experiments to test the effectiveness of their underride bars. According to Canadian regulation, underride bars must withstand twice the force of that required by the United States. All of the trailers the IIHS tested met U.S. and Canadian standards.

The major problem the researchers discovered was that during the overlap experiment (how far the car goes beneath the trailer upon collision), the test car had more than a 30% overlap with the trailer, which is the minimum overlap under which a passenger vehicle occupant’s head is likely to strike a trailer if an underride guard fails. All but one of the trailers failed the 30% overlap test.

The IIHS as well as the National Highway Traffic Safety Administration are continuously working to improve safety standards to provide safer roadways and protect motorists. In the future, as technology changes, the IIHS and NHTSA will be able to provide even better recommendations to keep the roadways safer for all drivers.

Original Article Published by the Insurance Institute for Highway Safety

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