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IIHS News | March 1, 2017Subscribe

IIHS recognizes semitrailers with good underride guards

ARLINGTON, Va. — Five North American semitrailer manufacturers earn the Insurance Institute for Highway Safety's new Toughguard award recognizing rear underride guards that are designed to prevent a range of deadly underride crashes. Semitrailers from Great Dane LLC, Manac Inc., Stoughton Trailers LLC, Vanguard National Trailer Corp. and Wabash National Corp. earn the accolade.

An underride guard is the metal bumper that hangs from the back of a semitrailer. The idea is to stop a smaller vehicle from sliding beneath a high-riding trailer in a rear-impact crash to preserve survival space for the people inside the lower-riding vehicle. All underride guards must meet federal safety standards, but IIHS research and crash tests have shown that many underride guards can buckle or break off in a crash. When guards fail, the resulting underride crashes often result in death or serious injury to people in passenger vehicles.

Passenger vehicle occupant deaths in crashes with large trucks

Year Passenger vehicle rear-ends large truck All crashes with large trucks
2015 427 2,646
2014 371 2,485
2013 354 2,410
2012 342 2,352
2011 260 2,241

The IIHS Toughguard winners have rear guards that prevent underride of a midsize car in three test modes — full-width, 50 percent overlap and 30 percent overlap. In each configuration, a midsize car travels at 35 mph toward a parked semitrailer. In the full-width test, which is the easiest to pass, the car strikes the center of guard head on. In the 50 percent overlap, half of the car's front end strikes the guard. In the toughest test, 30 percent of the front of the car strikes the trailer at its outermost corner. Underride guards are weakest at the outer edges of a trailer.

The Toughguard award is the culmination of six years of IIHS research and testing. The Institute began its underride crash test program in 2011 and has since evaluated multiple trailers from eight of the largest trailer manufacturers in North America.

"Our research told us that too many people die in crashes with large trucks because underride guards are too weak," says David Zuby, the Institute's executive vice president and chief research officer. "So we designed crash tests to replicate scenarios where guards have failed in real-world crashes. At first, only one of the semitrailers we evaluated passed all three tests — the Manac. Now five trailers do. Manufacturers really took our findings to heart and voluntarily improved their guard designs."

In the initial round of evaluations, the guards on all of the semitrailers prevented underride in the full-width test. In the 50 percent overlap, 7 of 8 guards prevented underride. In the 30 percent overlap, only Manac's guard stopped the car from underriding the trailer. Great Dane, Stoughton, Vanguard and Wabash subsequently reworked their designs and asked for retests.

The manufacturers used different countermeasures to toughen their guards. Stoughton, Vanguard and Wabash added vertical supports to the outboard edges, while Great Dane added larger fasteners to existing vertical supports to reduce the chances that the supports would be torn from the trailer. Great Dane also increased the size of the lower horizontal member of the bumper, which made it stronger. The new Great Dane design is the latest to be tested.

All of the changes manufacturers have made exceed current rules in place in the U.S. and Canada, as well as proposed new requirements from the National Highway Traffic Safety Administration that would essentially align U.S. underride regulations with Canadian ones.

Semitrailers from Hyundai Translead, Strick Trailers LLC and Utility Trailer Manufacturing Co. have passed the full-width and 50 percent overlap tests but not the 30 percent overlap evaluation. These three manufacturers are working on improvements, and IIHS will evaluate the new designs when they are available for testing.

"IIHS isn't a regulatory agency, and other than safety, there was no incentive for semitrailer manufacturers to make improvements," Zuby notes. "When we started testing, we weren't sure how they would respond. These companies deserve a lot of recognition for their commitment to addressing the problem of underride crashes."

In 2015, 427 of the 2,646 passenger vehicle occupants killed in large truck crashes died when the fronts of their vehicles struck the back of trucks. That is up 39 percent from 2011 when 260 of the 2,241 passenger vehicle occupants killed in large truck crashes died in impacts with the rear of a large truck. Gaps in federal crash data make it difficult to pinpoint exactly how many of these crashes involve underride.

In a 2012 IIHS study of fatal crashes between large trucks and passenger vehicles, an estimated 15 percent involved the rear of the truck. An IIHS analysis of a smaller sample of fatal crashes found that 82 percent involving the rear of the truck produced underride.

full underride test
Full-width test
50 percent underride test
50% overlap
30 percent underride test
30% overlap
TOUGHGUARD Great Dane
Applies to units equipped with the RIG30 rear impact guard system.
TOUGHGUARD Manac
Applies to all 90,000 series dry van, refrigerator and open top units built after June 2011.
TOUGHGUARD Stoughton
Applies to all dry van units built after October 2016.
TOUGHGUARD Vanguard
Applies to all dry van units built after December 2015 and all refrigerator units built after September 2016.
TOUGHGUARD Wabash
Applies to dry van units with the RIG-16 option built after February 2016.
Applies to refrigerated units with the RIG-16 option built after December 2016.
Hyundai Translead
Applies to all standard dry van and refrigerated units built after April 2011. 
Strick
Tested model: 2013 dry van 
Utility
Applies to trailers built after December 2012.

Results of underride guard evaluations

full underride test
Full-width
test
50 percent underride test
50%
overlap
30 percent underride test
30%
overlap

TOUGHGUARD
Great Dane
Applies to units equipped with the RIG30 rear impact guard system.
Full-width test
50% overlap
30% overlap
TOUGHGUARD
Manac
Applies to all 90,000 series dry van, refrigerator and open top units built after June 2011.
Full-width test
50% overlap
30% overlap
TOUGHGUARD
Stoughton
Applies to all dry van units built after October 2016.
Full-width test
50% overlap
30% overlap
TOUGHGUARD
Vanguard
Applies to all dry van units built after December 2015 and all refrigerator units built after September 2016.
Full-width test
50% overlap
30% overlap
TOUGHGUARD
Wabash
Applies to dry van units with the RIG-16 option built after February 2016. Applies to refrigerated units with the RIG-16 option built after December 2016.
Full-width test
50% overlap
30% overlap
Hyundai Translead
Applies to all standard dry van and refrigerated units built after April 2011.
Full-width test
50% overlap
30% overlap
Strick
Tested model: 2013 dry van
Full-width test
50% overlap
30% overlap
Utility
Applies to trailers built after December 2012.
Full-width test
50% overlap
30% overlap

See our full site for more information on large trucks.

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