Guardrail Flare Rates

The potential to increase suggested flare rates for strong post W-beam guardrail systems, and thus reduce guardrail installation lengths, is investigated. This reduction in length would result in decreased guardrail construction and maintenance costs and reduce impact frequency with only modest increases in impact severity. Computer simulation and five full-scale crash tests were completed to evaluate increased flare rates up to, and including, 5:1 on the Midwest Guardrail System (MGS). Impact severities during testing were found to be greater than intended, yet the MGS passed all NCHRP 350 requirements. Hence, flaring the MGS guardrail as much as 5:1 will still provide acceptable safety performance for the full range of passenger vehicles. Increasing guardrail flare rates will reduce the overall number of guardrail crashes without significantly increasing risks of injury or fatality during the remaining crashes. Therefore, it is recommended that whenever guardrail is outside of the shy line for adjacent traffic and the roadside terrain is sufficiently flat, flare rates increase to as high as 5:1.


  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; References; Tables;
  • Pagination: 17p
  • Monograph Title: TRB 86th Annual Meeting Compendium of Papers CD-ROM

Subject/Index Terms

Filing Info

  • Accession Number: 01044856
  • Record Type: Publication
  • Report/Paper Numbers: 07-0517
  • Files: BTRIS, TRIS, TRB
  • Created Date: Mar 30 2007 6:59AM