Trailer companies should be applauded for safety improvements

You don’t often leave a truck equipment press conference feeling as though you’ve been punched in the gut. But that’s exactly how I felt after hearing the heart wrenching story of Marianne Karth, who lost two children – aged 13 and 17 – in a 2013 highway crash.

Karth was driving in Georgia with three of her nine children when her car was struck by a tractor-trailer and sent careening into the rear of another trailer. The car impacted the underride guard at an angle and slid underneath the trailer. Daughter AnnaLeah died at the scene while her sister Mary died days later. Karth shared this story at a Stoughton Trailers press conference at the Technology & Maintenance Council’s (TMC) spring meeting, to applaud the trailer company for voluntarily strengthening its rear impact guard.

The rear impact guard is the bar mounted to the rear of a trailer, designed to prevent cars from sliding underneath the trailer in the event of a crash. It might be the most important part of a trailer’s design, given its ability to save lives, but it’s one that many of us take for granted.

The US-based Insurance Institute for Highway Safety (IIHS) began bringing the issue of rear impact guard design to the forefront in 2011 with the launch of its underride crash test program. In 2011, Manac was the only semi-trailer manufacturer to pass the rigorous 30% overlap test, which measures the guard’s ability to prevent underride when struck at an angle. The outer edges of the bar are understandably the weakest parts.

Karth has been lobbying US lawmakers to come out with a tougher standard, which would require all manufacturers to design rear impact guards capable of passing the 30% overlap test. But while the National Highway Traffic Safety Administration (NHTSA) has proposed tougher standards, the industry hasn’t been waiting for it to force its hands.

At TMC, Stoughton announced it voluntarily upgraded its rear impact guards to pass the 30% overlap test without adding any weight or cost to the design of its trailers. The new guards are now standard on Stoughton trailers. Great Dane also announced at the show it has upgraded its rear impact guards, by using larger fasteners on existing vertical supports, and strengthening the lower horizontal member of the bumper.

The day after Stoughton’s press conference, the IIHS released the results of its latest crash tests. In addition to Manac, Stoughton, and Great Dane, Vanguard and Wabash also joined the list of those trailer manufacturers who passed the 30% overlap test. All this was done voluntarily, before government forced their hands with tougher legislation. The achievement earned these five companies the IIHS’s new ToughGuard award, recognizing underride guards designed to prevent a range of deadly underride crashes.

The trailer manufacturers that have voluntarily taken steps to improve the safety of their equipment should be commended. These updates will save lives. IIHS reports that in 2012, 15% of fatal crashes involving a large truck and passenger vehicle involved the rear of the truck. Another study by IIHS found that 82% of crashes involving the rear of the truck produced an underride condition.

These design improvements won’t bring back Karth’s daughters, but they will surely save others from experiencing the pain and suffering she has had to endure.

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James Menzies is editor of Today's Trucking. He has been covering the Canadian trucking industry for more than 20 years and holds a CDL. Reach him at or follow him on Twitter at @JamesMenzies.

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