Not Good Enough: Underride Guards on Big Rigs

This article reports on an Insurance Institute for Highway Safety (IIHS) study that crash-tested eight semitrailers to see if their underride guards could stop a car from sliding underneath the trailers. Underride guards are steel bars that hang from the backs of trailers to prevent the front of a passenger vehicle from moving underneath the trailer during a crash. Most of the guards prevented underride crashes in the two easier tests but only one trailer passed the toughest test, which featured 30% overlap. The Institute uses a 30% overlap test because that is the minimum overlap under which a passenger vehicle occupant’s head is likely to strike a trailer if an underride guard fails. In each crash test, a 2010 Chevrolet Malibu struck a parked truck (from the eight largest manufacturers) at 35 miles per hour (mph). The trailers all had underride guards that met both U.S. and the more stringent Canadian standards. The author reminds readers of the danger of underride, discusses the results of earlier rounds of crash testing conducted in 2010 and 2011, and reviews some better designs, including that used by the Canadian manufacturer, Manac. The design spreads the underride guard supports further apart and not only does a better job preventing underride but also minimizes damage to the trailer itself in rear crashes.


  • English

Media Info

  • Media Type: Print
  • Features: Figures; Photos;
  • Pagination: pp 1-5
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 01492173
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 22 2013 8:22PM