This project documentation reports on the process of designing a wildlife crossing structure for an appropriate location on a rural highway in the State of Oregon. Firstly, the process included a review of scholarly documents on the topic of wildlife crossings. Reviewing such literature guided the author in the preliminary research required to select an appropriate location for a structure. In general, these structures should create continuity for wildlife movement patterns and not dead ends or cul-de-sacs. Preliminary research involved utilizing crash densities from the Oregon Department of Transportation and wildlife habitat information from the Oregon Department of Fish and Wildlife. Next, the author’s selection of the most feasible structure type depended on the total cost of the project. The following step included executing the structural engineering for the bridge superstructure and addressing important transportation safety elements for roadway users. The project process concluded with a final project cost estimate and a benefit-cost analysis of the structure with respect to the cost of vehicle-wildlife collisions. The superstructure design resulted in an 86-foot long span, 138-foot wide deck, 13-foot walls with a thickness of 16 inches that retain five feet of soil, and 15 84-inch segmental bulb I girders spaced at 9.5 feet. The selected exclusion fencing is 8-foot rectangular woven wire placed two miles north and south of the structure funneling wildlife for four miles. Lastly, the guardrail lining the traveled way and approaching the bridge is 250 feet of standard thrie-beam. Considering required materials and construction, the author estimated a total installed project cost of approximately $4.4 million. Given the annual benefit of more than $200k for preventing every vehicle-wildlife collision for the 75-year design life of the bridge, the benefit-cost ratio is 0.92.
