Recent crash tests conducted by an auto insurance research organization show that underride guards on tractor-trailers can fail in relatively low-speed crashes, with deadly consequences.
Now the Insurance Institute for Highway Safety (IIHS) is petitioning the federal government to require stronger underride guards that will remain in place during a crash, and to mandate guards for more large trucks and trailers.
According to the IIHS, rear guards are supposed to reduce underride deaths and injuries when a passenger vehicle crashes into the back of a tractor-trailer. Without an effective guard, death or serious injury can result if the trailer body crushes the passenger vehicle’s occupant compartment
“Cars’ front-end structures are designed to manage a tremendous amount of crash energy in a way that minimizes injuries for their occupants,” says Adrian Lund, IIHS president. “Hitting the back of a large truck is a game changer. You might be riding in a vehicle that earns top marks in frontal crash tests, but if the truck’s underride guard fails – or isn’t there at all – your chances of walking away from even a relatively low-speed crash aren’t good.
The IIHS recently conducted crash tests involving a 2010 passenger car crashing into the rear of three parked trailers. All three trailers had underride guards that complied with U.S. standards.
“Damage to the cars in some of these tests was so devastating that it’s hard to watch the footage without wincing,” Lund said. “If these had been real-world crashes there would be no survivors.”
Decapitation is a serious threat in underrides, the IIHS says. In three of the crash tests, the heads of the dummies in the car made contact with either the intruding trailer or the car’s hood after it tore free and pushed into the occupant compartment. The weakest guard tested involved a trailer whose underride guard bent forward, sheared its attachment bolts, and broke after the car hit it in the center rear at 35 mph.
In contrast, the best performing trailer successfully prevented underride of the car’s passenger compartment in a center-rear test at 35 mph, and was viewed as a survivable crash.
“Under current certification standards, the trailer, underride guard, bolts, and welding don’t have to be tested as a whole system,” Lund says. “That’s a big part of the problem. At the least, all rear guards should be as strong as the best one we tested.