Crash tests find tractor trailer underride guards often fail

Most tractor trailers are required to have underride guards, steel bars that hang from the backs of trailers to prevent a passenger car from moving underneath the truck during a crash. According to the IIHS, when a passenger vehicle ends up under a truck, the top of the occupant compartment gets crushed because the structures designed to absorb the energy of the crash are bypassed. The airbags and safety belts can’t do their jobs and people inside can experience life-threatening head and neck injuries.

Earlier research from the IIHS showed the minimum strength and dimensions required for underride guards were inadequate, prompting the Institute to petition the National Highway Traffic Safety Administration (NHTSA) in 2011 for tougher standards. The Institute also asked the NHTSA to consider applying the standards to other types of large trucks, such as dump trucks that aren’t required to have any underride guards.

Although the NHTSA has not yet responded, some trailer manufacturers have already started installing stronger guards. According to the IIHS, these guards generally work well to prevent underride, except in the crashes occurring at the outer edges of trailers, crash tests show.

Trucks in Canada have had to meet higher standards for underride guards since 2007, and the IIHS has drawn attention to this in recent crash tests. Under Canadian regulation, a guard must withstand about twice as much force as required by the U.S. at a point where it attaches to its vertical support

In a recent test of trailers with guards that met both U.S. and Canadian standards, IIHS engineers put trailers from the eight largest manufacturers through a serious of progressively tougher crash tests. In each crash test, a 2010 Chevrolet Malibu struck a parked truck at 35 mph. In the first scenario, the car was aimed at the center of the trailer, and all eight guards successfully prevented the underride. In the second test, in which only half the width of the car overlapped with the trailer, all but one trailer passed. However, when the overlap was reduced to 30%, every trailer except one from a Canadian manufacturer, failed. The institute uses a 30% overlap for the most challenging underride test because it is the minimum overlap under which a passenger vehicle occupant’s head is likely to strike a trailer if the underride guard fails.

Some safety advocates also feel that side guards should be mandatory. They are not required in the U.S., even though several countries do require them.

If you have been injured in a truck accident, Dan Munley and the Pennsylvania personal injury lawyers at Munley Law Personal Injury Attorneys can help.