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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

Effectiveness of Wildlife Mitigation Treatments along the Nelsonville Bypass

The Nelsonville Bypass is a 9 mile stretch of U.S. Route 33 that runs through the Wayne National Forest, an area high in species diversity and home to several threatened and endangered species. The motorist safety, economic and conservation values of building effective mitigation features that reduce vehicle-wildlife collisions along the bypass have been nationally recognized. Mitigation features include: high and low fencing to reduce wildlife trespass into the right-of-way (ROW), uni-directional jump outs for wildlife exit from the ROW, underpasses and ecopassages to maintain habitat connectivity across the highway, high-mast lighting to lure bats above traffic flow, and replacement of wetlands and bat roosting habitat. This two-year study employed road surveys, continuous monitoring of jump outs and wildlife passages, population estimations, detailed mapping of fence structures and breaches, and radio telemetry of an endangered target species. Road surveys of the bypass and control highways revealed that the mitigation structures reduced deer-vehicle collisions, but collisions still occurred on the bypass. Although, generally well-constructed, the authors identified several ways in which the mitigation features could be made more effective. Placement of fencing near the outer boundary of the ROW made it vulnerable to damage from erosion and tree falls, and isolated high-quality habitats within the ROW. Placement of the fence within 30-50 ft. of the roadway on less rugged terrain away from the forest would likely reduce costs of construction and maintenance while allowing wildlife access to habitat within the ROW. The authors also recommended regular maintenance inspections and mowing on both sides of the fencing. Jump outs were effective uni-directional exits, but wildlife, particularly deer, were not compelled to exit the expansive area within the ROW fencing. Placement of the fence with jump outs closer to the road would reduce habitat within the fence and combined with traffic noise may increase jump out use. Large wildlife underpasses and crossings were well used by a variety of mammal species. Smaller mammals used the small wildlife ecopassages. Reptiles and amphibians avoided the use of underpasses and road mortality rates of amphibians were high on Ohio State Route 78 (tributary road) near wetlands. Placement and passage design were contributing factors to high amphibian mortality. Radio-tracking of rattlesnakes discovered that snakes easily trespassed the small wildlife fencing and used the habitat within the ROW, likely because it was warmer than the surrounding forested habitat. No road mortality or attempted road crossings by rattlesnakes were detected. Finally, while bats foraged near the lights, most species were detected with equal frequency at different heights under the lighting. This report details these findings and provides additional recommendations to improve design and construction of wildlife mitigation features both along the Nelsonville Bypass, and for future design of mitigation features for roadways in high-density wildlife areas.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Maps; Photos; References; Tables;
  • Pagination: 239p

Subject/Index Terms

Filing Info

  • Accession Number: 01685219
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/OH-2018-8
  • Contract Numbers: SJN 135024
  • Files: NTL, TRIS, ATRI, USDOT, STATEDOT
  • Created Date: Nov 12 2018 5:15PM