Evaluation of Wildlife Crossing Structures on US 93 in Montana’s Bitterroot Valley

Wildlife-vehicle collisions (WVC) are an ecological problem and a safety issue. Wildlife crossing structures are effective for reducing WVC. Twelve pre-construction sites, three control sites, and 19 wildlife crossing structures (12 bridges, seven culverts) were monitored with motion-detection cameras to determine white-tailed deer (Odocoileus virginianus) use rates. Performance measures were established from pre-construction and control monitoring, and were used to evaluate post construction use rates. Cameras recorded white-tailed deer moving through structures on 24,878 occasions. Nine structures (eight bridges, one culvert) exceeded performance measures. Statistical analyses were used to assess differences and relationships among post-construction rates, structural characteristics, and environmental characteristics. Structure type and dimensions, guard rail length, and shrub cover had significant effects on rates. Bridges had higher success than culverts. Changes in WVC crash rates were evaluated. Structures did not have a significant effect on WVC crash rates. However, substantial relative reductions and increases in WVC crash rates did occur at structures. The largest reduction was -2.6 crashes/year/mile. White-tailed deer abundance appears to be the most dynamic and important variable affecting WVC crash rates. Width (span) should be maximized for wildlife crossing structures, length should be minimized, and height should be maximized. Dimension recommendations should be prioritized in the order listed.


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 104p

Subject/Index Terms

Filing Info

  • Accession Number: 01730000
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/MT-17-003/8194
  • Contract Numbers: Project # 8194
  • Created Date: Feb 3 2020 12:23PM