Standards for Underride Guards on Tractor-Trailers Should be Updated

The Insurance Institute for Highway Safety is petitioning the U.S. government for stronger underride guards that will remain in place during a crash. The Insurance Institute for Highway Safety is also requesting the federal government to mandate guards for more tractor trailers.  Recent crash tests by the Institute have shown that underride guards on tractor-trailers can fail in fairly low-speed crashes.  

Rear guards are the primary countermeasure for preventing underride injuries and deaths when an automobile collides into the rear of a tractor-trailer. Because the upper part of an automobile   occupant compartment usually crushes as the truck body intrudes into the vehicle safety cage, underride makes serious injury or death more likely.  In 2009, 70% of the 3,163 people who died in all tractor-trailer collisions were occupants of automobiles or other passenger vehicles.  The Insurance Institute for Highway Safety’s president, Adrian Lund, stated:

Cars’ front end structures are designed to manage a tremendous amount of crash energy in a way that minimizes injuries for their occupants.  Hitting the back of a large truck is a game changer.  You might be riding in a vehicle that earns tops 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 Institute has examined the underride collision problem for over 30 years, including mid-1970s collision tests which showed how then-current underride guards were not effective in preventing underride.  In the most recent study, the Insurance Institute for Highway Safety studied examples from the Large Truck Crash Causation Study, a federal database of approximately 1,000 collisions in 2001-03, to identify collision patterns causing rear underride of heavy trucks and semi-trailers with and without guards.

Of the 115 collisions involving automobiles striking the back of a heavy trucks or semi-trailers, underride was a common outcome.  Approximately 22% of the collisions did not involve underride or included negligible underride.  Twenty three of the twenty eight cases in which a person in the passenger vehicle died involved severe or catastrophic underride damage, meaning the entire front end or more of the vehicle slid under the tractor trailer.  The National Highway Traffic Safety Administration estimates that approximately 423 people in automobiles die each year when their cars strike the rear of tractor trailers.  Regarding this issue, Adrian Lund stated:

Under current certification standards, the trailer, underride guard, bolts, and welding don’t have to be tested as a whole system. 


That’s a big part of the problem.  Some manufacturers do test guards on the trailer.  We think all guards should be evaluated this way.  At the least, all rear guards should be as strong as the best one we tested.  Another problem is that regulatory gaps allow many heavy trucks to forgo guards altogether.  When they are present on exempt trucks, guards don’t have to meet 1996 rules for strength or energy absorption.  Underride standards haven’t kep peace with improvements in passenger vehicles crashworthiness.  Absent regulation, there’s little incentive for manufacturers to improve underride countermeasures, so we hope NHTSA will move quickly on our petition.

If you need additional information on this matter contact Boyd Newton, an Atlanta Truck Wreck Attorney.

Source: Insurance Institute for Highway Safety, March 1, 2011.

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