Effectiveness of Night-time Speed Limit Reduction in Reducing Wildlife-Vehicle Collisions

Wildlife-vehicle collisions are dangerous and costly to the traveling public and pose a threat to wildlife populations. Transportation managers continue to evaluate the effectiveness of measures that have been employed to reduce wildlife-vehicle collisions (WVCs). One potential measure is to reduce the posted speed limit at night and during dawn and dusk hours. The theoretical mechanism for this measure to work is that drivers reduce their operating speeds, increasing their stopping distances when they see an animal in the road, and therefore avoiding collisions with those animals. Although reduced night-time speed limits are being used in many places with the goal of reducing WVCs, there has been almost no research to evaluate whether drivers reduce their operating speeds and whether a reduction in the number of WVCs results. The authors conducted a thorough experiment in which posted speed limits were reduced from 70 mph to 55 mph during dusk to dawn hours in key deer activity seasons at six sites in southwestern Wyoming. Drivers reduced their speeds in response to the posted speed limit reduction, but the average reduction was only 3-5 mph. At winter sites, where the reduced speed limit was in effect for seven months, there was no evidence of any reduction in WVCs. At migration sites, where the reduced speed limit was in effect for two months at a time, there was some evidence of fewer WVCs, although it was not clear that this could be attributed to the reduced speed limit. The authors recommend that reduced posted speed limit is not an effective measure to reduce WVCs on high-speed rural two-lane highways.


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Maps; Photos; References; Tables;
  • Pagination: 64p

Subject/Index Terms

Filing Info

  • Accession Number: 01720620
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-WY-1904F, RS11216
  • Created Date: Oct 18 2019 12:30PM