From the U.S. Government Accountability Office, www.gao.gov

Transcript for: Underride Crashes and Testing of Underride Guards 

Description: An underride crash is a type of motor vehicle crash in 
which a car slides under the body of a large truck due to the height 
difference between the vehicles. GAO reviewed the data the Department 
of Transportation reports on underride crashes and the development and 
use of underride guard technologies in the U.S.

Related GAO Works: GAO-19-264: Truck Underride Guards: Improved Data 
Collection, Inspections, and Research Needed

Released: April 2019


[ GAO logo on a black background ] An underride crash is a type of 
motor vehicle crash in which a car slides [ A car crashes into the side 
of truck and slides underneath it ] under the body of a large truck due 
to the height difference between the vehicles.

[ View from the inside of the car of a car crashing into the side of 
the truck and sliding underneath it ] Often, the car's safety features, 
like airbags, do not activate and the truck may intrude into the 
passenger compartment, leading to severe injuries or fatalities.  [ An 
animated truck appears on the screen to show rear underride and side 
underside guards ] To help mitigate these types of crashes, rear 
underride guards are required on most trailers. While not required, 
side underride guards are being developed.

[ A car crashes into the side of truck and slides underneath it ] The 
Insurance Institute for Highway Safety has [ View from underneath the 
truck of a car hitting the rear underride guard ] tested rear- and 
side-underride guards to assess their effectiveness at preventing an 
underride crash. During this test, [ Video showing a car crashing into 
the underride guard of a truck and then sliding underneath of it ] the 
rear guard was ineffective. The car went under the trailer and the 
trailer entered into the passenger compartment.

[ Video shows a car crashing into the rear underride guard of a truck 
and does not slide underneath of it ] In this crash test of an 
effective rear guard, the air bags deployed, and the car did not slide 
under the trailer.

[ An animated truck shows up on the screen to show the placement of 
aerodynamic side skirts ] The sides of some trailers are equipped with 
aerodynamic side skirts to save fuel. [ A car crashes into the side of 
truck with an aerodynamic side skirt and slides underneath it ] 
However, these panels are not able to stop a car from going underneath 
a trailer.

[ A video of an aerial view of a crash plays while the words 
“GAO-19-264” and “gao.gov” appear on the screen ] For more information 
on truck underride guards, check out our report at gao.gov.