The Insurance Institute for Highway Safety (IIHS) has conducted extensive tests on the efficacy of side underride guards.
In 2015, over 300 people were killed in side impact crashes with semi-trucks. The IIHS believes that side underride guards could prevent many of these fatal accidents. IIHS data indicates that side underride guards have the potential to reduce the risk of injury by three-fourths and to stop about 90 percent of fatal crashes involving side underride accidents.
According to the president of Advocates for Highway and Auto Safety, “These are crucial protections because frequently in side underride crashes, the front seat occupants are killed when the vehicle goes under a truck and shears off the top of the vehicle.”
The IIHS tests show that even at 35 miles per hour, a regular vehicle striking the side of a semi’s trailer slides right under the trailer. An accident like that would most likely kill anyone sitting in the front seat.
When trailers are equipped with side guards, the vehicle is stopped before it can slide underneath.