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We put the spotlight on the Insurance Institute for Highway Safety recommendation for semi trailer underride guards:
The Insurance Institute for Highway Safety is asking the federal government to mandate the use of stronger and safer underride guards on semi trailers. The request comes after a series of crash test studies which demonstrated a significantly higher degree of survivability of rear-end collisions with a semi trailer.
The underride guards are fitted to the rear of the semi trailer and are seen as the principal safety measure for preventing injuries and fatalities when a vehicle collides with the trailer.
The Insurance Institute performed an analysis of over 1,000 real-world incidents between 2001 and 2003, of which 115 cases involved a collision with the rear of the trailer. Over three-quarters of the rear enders resulted in the smaller vehicle being forced under the rear of the trailer. When the Institute looked at the data from crashes which were fatal, they found that 23 out of the 28 cases involving a fatality involved a rear end collision where the vehicle went under the rear of the trailer.
In addition to the empirical data, the Institute also conducted its own crash tests. They used three different rear trailer guards which met US rules (though only two of them met the more stringent Canadian rules on this issue).
All of the trailer guards demonstrated underride to some extent (though a Wabash trailer guard did prevent underride provided the collision was in the direct center of the guard). A 2010 Chevrolet Malibu traveling at 35 miles per hour was used in the crash tests.
Despite the failure to prevent underride using a trailer guard, the Institute still believes that underride guards will provide an increased measure of protection in the event of a collision. A major issue is that modern automobiles are built with safety in mind, and they are able to withstand enormous stresses generated in front-end collisions, however when you have a 5,000 pound car colliding with an 80,000 pound 18-wheeler, something has to give and ti usually is not the truck or trailer unit.
In the US there are significant loopholes within the regulatory regime dealing with collision safety. Many trucks currently operating on the road are able to do so without any guards at all. Despite the negative results of the Insurance Institute’s testing, it does seem self-evident that reducing the impact of an underride is going to improve the potential to survive the event as well as reduce the level of injuries sustained by the car occupants.