Effectiveness of Wildlife Underpasses and Fencing to Reduce Wildlife‐Vehicle Collisions

Abstract

Transportation planners are increasingly incorporating roadway design features to mitigate impacts of highways on wildlife and to increase driver safety. We used camera and track surveys to evaluate wildlife use before and after construction of 3 wildlife underpasses and associated fencing on a new section of United States Highway 64 in Washington County, North Carolina, USA. We recorded 242 occasions of white-tailed deer (Odocoileus virginianus) use of underpass areas before highway construction began. Following completion of the highway, we collected 2,433 photographs of 9 species with deer representing 93% of all crossings. Adjusting for differences in number of monitoring days, white-tailed deer use of underpass areas averaged 6.7 times greater after the new highway and underpasses were completed. We recorded 3,614 wildlife crossings of L 20 species based on track counts, representing most medium and large mammals known to occur in the area and several reptiles and birds. After completion of the highway, we documented wildlife mortality due to vehicle collisions during a 13-month period and recorded 128 incidences representing L 24 species. Within fenced highway segments, mortalities were lowest near underpasses and increased with distance from the underpasses. However, we also documented more mortalities in fenced areas compared with unfenced areas. With greater distance from an underpass, animals with smaller home ranges seemed less likely to reach the underpass and instead attempted to climb over or crawl under fencing. Based on collision reports from adjacent highway sections, the new section of United States Highway 64 experienced approximately 58% fewer wildlife mortalities (primarily white-tailed deer), suggesting underpasses and fencing reduced the number of deer-vehicle collisions. Continuous fencing between underpasses may further reduce the number of vehicle collisions for deer but additional design features (e.g., buried fencing) should be considered for other wildlife species.

Context‐dependent effects on spatial variation in deer‐vehicle collisions

“…These results are consistent with theoretical models that consider how animal body size, movement speed, traffic volume and road width influence DVC (Van Langevelde and Jaarsma 2004). Mitigation measures along roads characterized by high traffic volume should therefore focus on deterring wildlife access to the road surface, i.e., with exclusion fencing (Clevenger et al 2001, Olsson and Widen 2008, McCollister and Van Manen 2010, Gagnon et al 2011.…”

Fragmentation of the Habitat of Wild Ungulates by Anthropogenic Barriers in Mongolia

“…Modifying the fences (e.g., raising the lowest wire) might be effective, because the gazelles can cross these barriers, but larger livestock, such as horses, cows, and camels, cannot [24]. Creating new passages for the animals, such as the over- and under-passes created along the Qinghai–Tibetan Railway in China [36] and along highways in North America [37], [38], [39], would be also effective, but this approach would be expensive. For new railroads that are currently being planned or are under construction, no fence zones or passages for animals with a suitable structure should be created at frequent intervals.…”

Modeling road mortality hotspots of Eastern Hermann’s tortoise in Romania

“…An array of mitigation methods have been proposed and implemented, such as signage, driver education, temporary road closures, underpasses and overpasses and, roadside fencing (Glista et al, 2009;McCollister and Van Manen, 2010). In some instances, teams of volunteers may help animals cross roads during mass migrations (e.g., spring amphibian migrations towards breeding ponds; Bonardi et al, 2011).…”