Pictured: Wildlife fencing along I-64 near Charlottesville leads deer and other wildlife to an existing box culvert beneath the interstate. The addition of fencing to existing underpasses resulted in a 92% reduction in deer-vehicle collisions.
Photo Credit: VDOT, Virginia Transportation Research Council
Wildlife crossings are underpasses or overpasses that allow wildlife to pass unharmed beneath or above a road to access important habitat. This connection also helps prevent the isolation of wildlife populations, which can increase the risk of eventual extirpation or local extinction. Many underpasses function as wildlife crossings even if they weren't designed for that purpose.
Wildlife crossings can vary in size depending on the target species. There is a great deal of research on wildlife crossing designs that are most successful for particular species.
One of the objectives of VSWCC is to identify existing underpasses that are or could be used by wildlife and work towards implementing measures to increase their use. Adding fencing along the roadside and connecting it to an underpass can help guide wildlife to the structure and keep them off the road.
Other measures that make a structure more attractive to wildlife is adding natural substrate along the bottom of the underpass, adding vegetation near the culvert openings, placing rocks or other material in the structure to serve as hiding places, and - for culverts that carry water- adding dry areas or shelving to allow animals to cross.