In IIHS test, rear crash guards on truck fail to prevent serious crash

In this IIHS test, rear crash guards on a tractor trailer truck fail to prevent the car behind it from sustaining serious damage in a crash. (This is a screen capture from the IIHS video that appears at the bottom of this blog post.)

The U.S. Insurance Institute for Highway Safety (IIHS) has released a report saying that tractor trailer trucks need better rear crash guards in order to prevent cars from sliding under the trucks from behind in case of an accident, as Jonathan Welsh writes for The Wall Street Journal blog Drivers Seat.

Jeffrey N. Ross reports for Autoblog that IIHS performed three tests on eight of the most popular semi-trailers, including a full-width impact test, a 50% overlap test (in which only half of the car makes contact with the trailer) and a narrower, 30% overlap test. The tests were done at 35 miles per hour, using a 2010 Chevrolet Malibu. In the full-width crash, all of the trailers safely prevented the cars from underriding (going under the trucks). This, Ross writes, is a big improvement in safety as compared with results from the same test two years before.

In this new series of tests, all but one truck passed the test involving half the width of a car, Welsh writes. He notes that the trucks tested were from Great Dane, Hyundai, Manac, Stoughton, Strick, Utility, Vanguard, and Wabash, and that all of the trailers had underride guards that met both U.S. and Canadian safety standards. He writes: “Under the Canadian regulation, a guard must withstand about twice as much force as required by the U.S. rule at the point where it attaches to its vertical support, IIHS said.”

In a press release, IIHS writes that although tractor trailer manufacturers have improved rear crash guards in recent years to be much stronger than the National Highway Traffic Safety Administration (NHTSA) requires, such rear guards (except for one made in Canada by Manac) are not effective in the case of crashes involving a 30% overlap of a car and the truck in front of it on the road.

IIHS writes:

All the improvements in occupant protection that have helped drive down crash deaths in recent decades count for little when the front of a passenger vehicle ends up under a truck. When this happens, the top of the occupant compartment gets crushed because the structures designed to absorb the energy of a crash are bypassed. The airbags and safety belts can’t do their jobs, and people inside can experience life-threatening head and neck injuries.

IIHS explains how the rear crash guards made by Manac — whose guards were the only ones to pass the IIHS’s 30% overlap test — are different from all other rear crash guards:

The supports of its underride guard are attached to a reinforced floor and spaced just 18 inches from the edge. The Malibu and the dummy inside it not only fared better, but the Manac trailer also had damage estimates among the lowest of all the trailers. It required only a replacement underride guard.

“Our tests suggest that meeting the stronger Canadian standard is a good first step, but Manac shows it’s possible to go much further,” says David Zuby, chief research officer for IIHS.

Here is IIHS’s video showing the crash tests:

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