Montana Department of Transportation

Malcolm “Mack” Long, Director

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Research

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

collage of animal photos taken at US 93 wildlife crossing structures

Collisions between wild animals and automobiles are a problem for some wildlife populations and a safety issue for motorists in Montana and across North America. Wildlife crossing structures with wildlife exclusion fencing is the most effective method to reduce wildlife-vehicle collisions (WVC) and allow animals to safely move across roads. The Montana Department of Transportation (MDT) installed 19 wildlife crossing structures for large animals within a suburban-wildland setting along US 93 between Florence and Hamilton from 2004 to 2012. The purpose of this research was to evaluate the effectiveness of these wildlife crossing structures for whitetailed deer. Post-construction monitoring cameras recorded white-tailed deer successfully moving through the wildlife crossing structures on 24,878 occasions. Six wildlife crossing structures (five bridges and one large culvert) had success rates greater than 90 percent. Nine wildlife crossing structures (eight bridges and one culvert) exceeded the performance measures. Ten structures (four bridges, six culverts) did not exceed the performance measures. Success rates for wildlife crossing structures increased with increasing width, openness, guardrail length, and shrub cover. Success rates decreased as structure length (the distance a deer moved through the structure) increased.

Wildlife Crossing Videos

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