Wellbuilt underride guard protective devices on truck trailers can prevent these types of collisions mdash which account for about one out of every five passenger vehicle occupant deaths in twovehicle crashes between passenger cars and heavy trucks each year mdash according to a new study from IIHS released today IIHS photo

Trailer underride guards vs. aero skirts: Potential to save lives

May 10, 2017
Study finds reinforced guards instead of aero side skirts could stop roof-crush, decapitation in collisions with passenger cars

Underride guards on the sides of semi-trailers rather than aero side skirts can effectively prevent decapitation and other roof-shear/ crush injuries in a T-bone-type side collision with a passenger car, a new study has found.

In the study released today, the Insurance Institute for Highway Safety (IIHS) ran two tests crashing a passenger sedan at 35 mph into the side of a 53-ft. dry van trailer. In one test, the trailer had an AngelWing side underride protection device, which on the surface looks similar to an aerodynamic skirt but has strong reinforcing beneath.

The passenger car in that test hit the side of the trailer but struck and was repelled as in a normal collision. The car's airbags and seat belts did what they're designed to do and restrained and protected the test dummies from the collision force.

In the second test, the passenger car hit the side of the trailer and kept going, shearing off part of its roof and wedging the car beneath the trailer. "In a real-world crash like this, any occupants in the car would likely sustain fatal injuries," the study authors concluded.

Installing underride guards like the AngelWing device made by AirFlow Deflector is an important safety upgrade for truck trailers, they advised, since nearly one out of five passenger vehicle occupants killed in two-vehicle collisions with heavy trucks died because the car went under the trailer in these kinds of roof-shear/ wedged-underneath wrecks.

AngelWing underride guard vs. aero side skirt

Crash data from 2005-2015 show roughly 20-25% of passenger car occupant fatalities in collisions with heavy trucks are caused when the passenger car gets wedged beneath a truck trailer in a side/ T-bone-type impact. (Source: IIHS - CLICK TO ENLARGE)

That roughly 20% portion of side-collision-related passenger car occupant deaths has been consistent going back more than a decade, and likely has been the case for much longer.

Data from heavy truck-passenger car crashes over the 2005-2015 period indicate that with the exceptions of 2008 and 2011, side impacts caused between 20-24% of passenger vehicle occupant fatalities. Under-trailer side impacts were responsible for 19% of passenger car occupant deaths in 2008 and 18% in 2011 (see chart).

Meanwhile, passenger car occupant fatalities from rear-end collisions into a truck trailer accounted for fewer deaths across the board, although fatalities from those types of collisions have been approaching closer parity with trailer side impact-related deaths.

Watch more from AirFlow Deflector on how underride guards work:

About the Author

Aaron Marsh

Before computerization had fully taken hold and automotive work took someone who speaks engine, Aaron grew up in Upstate New York taking cars apart and fixing and rewiring them, keeping more than a few great jalopies (classics) on the road that probably didn't deserve to be. He spent a decade inside the Beltway covering Congress and the intricacies of the health care system before a stint in local New England news, picking up awards for both pen and camera.

He wrote about you-name-it, from transportation and law and the courts to events of all kinds and telecommunications, and landed in trucking when he joined FleetOwner in July 2015. Long an editorial leader, he was a keeper of knowledge at FleetOwner ready to dive in on the technical and the topical inside and all-around trucking—and still turned a wrench or two. Or three. 

Aaron previously wrote for FleetOwner. 

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