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Evaluation of Wildlife Mitigation Measures Along US Hwy 93

Project #: 4W2076
Start Date: 04/01/2008
End Date: 09/30/2011
Status: Completed

The most extensive wildlife-crossing mitigation project in North America, in terms of both road length and the number of crossing structures, is being undertaken as part of the reconstruction of U.S. Highway 93 in northwestern Montana. Begun in October 2004, the reconstruction includes measures to reduce wildlife/vehicle collisions and measures that allow animals to cross the road safely. Wildlife jump-outs are also provided to allow animals to escape the road corridor. With a key portion of the reconstruction completed, Western Transportation Institute researchers have begun a study to measure the effectiveness of the mitigation measures. Data on animal/vehicle collisions will be collected to determine whether the design measures reduced accidents. Use of the crossing structures by different species will be documented and, where sample size allows, compared to other factors such as co-use by humans, roadway characteristics and crossing structure dimensions. In addition, use of the structures specifically by deer and bear will be compared to pre-construction use by those species to investigate whether the animals can still move across (or under) the road as much as they used to, before the road was upgraded and the mitigation measures were implemented. Jump-out height will also be studied to determine the optimal dimensions for encouraging use by wildlife, particularly deer. The data from this study will be combined with the monitoring work that will start in 2010, when the reconstruction project is fully complete, to enhance the quality of the data for these sections of the roadway.


Study the effectiveness of eleven wildlife underpasses, 29 jump-outs and two wildlife guards (equivalent to cattle guards) in terms of wildlife movements and wildlife/vehicle collisions on U.S. Highway 93 near Ravalli, Montana. In addition, the effectiveness of other, more isolated, wildlife crossing structures and shorter fencing on other locations along U.S. 93 between Polson and Evaro Hill, Mont., will be investigated in terms of a potential reduction in animal/vehicle collisions.