Semitrailers have a safety feature on the back known as underride guards. These guards are supposed to stop vehicles from riding underneath semis during a crash. If the guards prevent a car from riding underneath, the chances of survival are greatly increased.
Unfortunately, research has shown that these guards are not sturdy enough to prevent cars from crashing underneath semitrailers.
The Insurance Institute for Highway Safety (IIHS) says that the current standards for rear guards are inadequate to prevent underride collisions.
Underride guards are most effective when a vehicle directly impacts the rear of a tractor-trailer. However, most manufacturers failed when a car struck the corner of the guard. IIHS says that current guards space the vertical supports 28 inches from the edge of a trailer.
To fix this problem, IIHS says that the vertical supports should be spaced 18 inches from the edge of a trailer. By spacing the vertical supports wider apart, more support is given to the edges of the underride guard.
Is the Government Requiring Sturdier Underride Guards?
Although the government has been accused of reacting slowly to the issues surrounding underride guards, it is planning to make changes. According to ABC 7, the National Highway Traffic Safety Administration (NHTSA) is in the process of increasing the safety requirements of underride guards.
The Executive Director of the Truck Safety Coalition says the new standards will make the rear guard “stronger and lower to the ground,” which will prevent passenger vehicles from riding underneath trucks.
Source: http://www.iihs.org/iihs/sr/statusreport/article/48/2/1