According to the Insurance Institute for Highway Safety, a nonprofit organization, underride guards mounted on the sides of trucks in Kentucky and throughout the country offer similar safety benefits to those that are mounted on the rear of the vehicles. Regulations mandating rear underride guards are under consideration.
The IIHS did two crash tests in 2017. One was using an underride guard and the other was using a fiberglass side skirt that was not designed for underride protection. In both 35-mph crash tests, a 53-foot dry van trailer was hit in the center by a mid-size passenger car. The first test used the underride protection, and while it bent, it also prevented the car from going under the truck. In the second test, using the side skirt, the roof came off and the car became wedged under the truck. According to the IIHS, that crash probably would have been fatal for vehicle occupants.
As a result of these tests, the IIHS says that side underride guards should be mandated as well. This was the first evaluation of a side guard by the IIHS.