Statistics from the National Highway Traffic Safety Administration (NHTSA) show that around 423 people in passenger vehicles are killed each year in truck accidents, with an additional 5,000 injured.

According to the Insurance Institute for Highway Safety (IIHS), these fatalities and injuries occur because of inadequately designed underride guards on tractor-trailers that fail to prevent intrusion into the passenger cars when a rear-end collision occurs. Such intrusion occurs even at speeds that would result in minimal or no injuries if the car struck another passenger vehicle.

The IIHS and other auto insurance groups are pushing U.S. regulators to require tractor-trailers and other truck types to have underride guards that will withstand rear-end collisions at certain speeds that will minimize the risks of injury.

Also, the guards on trucks are certified separately from the trailers to which they are attached. Adrian Lund, president of the IIHS, would like to see the NHTSA require that the trailer, underride guard, bolts and welding be tested as a whole.

The IIHS conducted crash tests on a 2010 Chevy Malibu by deliberately crashing into the rear of trailers at 35 mph using three different rear guards. The Wabash trailer performed the best at head-on impacts.

When the trailers were impacted at different angles, however, the Vanguard and Hyundai guards severely underperformed at the same speed, with a 30 percent overlap, which would have produced fatal results. The study indicated that the guards worked as intended only when the trailers’ centers were struck dead-on.

The IIHS would like the guards strengthened and to have the attached hardware remain intact during testing. It would also like to end the exemptions for underride guard regulations on other truck units.