Safety Evaluation of Improved Curve Delineation

The Federal Highway Administration (FHWA) organized a pooled fund study of 26 States to evaluate low-cost safety strategies as part of its strategic highway safety effort. One of the strategies chosen to be evaluated for this study was improving curve delineation. Geometric, traffic, and crash data were obtained at 89 treated curves in Connecticut and 139 treated curves in Washington to determine the safety effectiveness of improved curve delineation. Treatments varied by site and included new chevrons, horizontal arrows, and advance warning signs as well as the improvement of existing signs using fluorescent yellow sheeting. All sites were on two-lane rural roads. To account for potential selection bias and regression-to-the-mean, an Empirical Bayes (EB) before-after analysis was conducted. The aggregate results revealed an 18% reduction in injury and fatal crashes, a 27.5% reduction in crashes during dark conditions, and a 25% reduction in lane departure crashes during dark conditions. The reductions were more prominent at locations with higher traffic volumes and sharper curves (curve radius less than 492 ft) and in locations with more hazardous roadsides (roadside hazard rating (RHR) of 5 or higher) compared to locations with less hazardous roadsides (RHR of 4 or lower). In addition, curves where more signs were either added or replaced (with a more retroreflective material) within the curve experienced larger reductions in crashes. An economic analysis revealed that improving curve delineation with signing improvements is a very cost-effective treatment with the benefit-cost ratio exceeding 8:1.

  • Record URL:
  • Corporate Authors:

    Vanasse Hangen Brustlin, Incorporated

    8300 Boone Boulevard, Suite 700
    Vienna, VA  United States  22182-2626

    Persaud and Lyon, Incorporated

    87 Elmcrest Road
    Toronto, Ontario  Canada  M9C 3R7

    University of North Carolina, Chapel Hill

    Highway Safety Research Center
    Chapel Hill, NC  United States  27599

    Federal Highway Administration

    Office of Safety Research and Development
    6300 Georgetown Pike
    McLean, VA  United States  22101-2296
  • Authors:
    • Srinivasan, Raghavan
    • Baek, Jongdae
    • Carter, Daniel
    • Persaud, Bhagwant
    • Lyon, Craig
    • Eccles, Kimberly A
    • Gross, Frank
    • Lefler, Nancy X
  • Publication Date: 2009-9


  • English

Media Info

  • Media Type: Web
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 56p

Subject/Index Terms

Filing Info

  • Accession Number: 01153220
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-HRT-09-045
  • Contract Numbers: DTFH61-05-D-00024 (VHB)
  • Files: TRIS, USDOT
  • Created Date: Mar 24 2010 9:09AM