Semi Truck Underride Guard & Side Guard Crash Test – Video

Rear underride guards are steel bars that hang from the backs of large trucks to prevent a passenger vehicle from moving underneath in a rear crash. Crashes with underride typically involve severe damage to the occupant compartment of the smaller vehicle, often with deadly results.

IIHS evaluates the performance of rear underride guards on truck trailers made by the major manufacturers. In the tests, a midsize car traveling 35 mph is crashed into the back of a parked semitrailer. Each trailer is tested in three configurations:

Full width

The car crashes into the center of the truck’s rear.
50 percent overlap.

Half of the car’s width overlaps the rear of the truck.
30 percent overlap.

Thirty percent of the car’s width overlaps the rear of the truck.
Trailers that pass all three tests — meaning there is no underride in any of the crashes — qualify for the IIHS TOUGHGUARD award.