Promoting Safety and Reducing Wildlife-Vehicle Collisions Through Effective Wildlife Crossing Infrastructure: Identifying Infrastructure Best Practices

Abstract

The 2021 Bipartisan Infrastructure Law established the Wildlife Crossing Pilot Program, committing $350 million over five years to fund wildlife crossing projects across the country. Wildlife crossings, such as overpasses and underpasses, seek to minimize wildlife-vehicle crossings and improve habitat connectivity. Wildlife crossings aid the mitigation of the negative effects of roads and highways on wildlife populations. Wildlife-vehicle collisions are accidents in which an animal collides with a vehicle, injuring and killing humans and animals. Over one million wildlife-vehicle collisions occur annually, causing over $8.4 billion in property damages. A single wildlife-vehicle collision can cause up to $42,000, depending on the species hit. Wildlife crossings also reduce wildlife habitat fragmentation – the division of habitat into smaller segments, often by human intervention. Roads are common sources of habitat fragmentation, especially in rural areas. Habitat fragmentation leads to both reduced species population and diversity. There are several interventions that reduce wildlife-vehicle collisions, but do not address habitat fragmentation. For example, fencing is a common tool used to address wildlife-vehicle collisions, but fences make habitat fragmentation worse. Wildlife crossings tackle both wildlife-vehicle collisions and habitat fragmentation. The first wildlife crossings in the United States were constructed in the 1970s. Since then, thousands of crossings have been built nationwide. As wildlife crossing design evolves, lessons learned are making crossings more effective. Through a literature review, case studies, and a roadkill hotspot analysis, this paper identifies best practices for constructing wildlife crossings. The literature review identified key factors of a successful wildlife crossing project:

the use of fencing in tandem with crossing infrastructure, the consideration of landscape features, establishing design standards, restricting human interaction with crossings, and routinely monitoring the infrastructure.

Three case studies provided examples of crossing infrastructure in practice. Lessons learned from I-75 in Florida, Banff National Park, and Northeastern Nevada further contextualize the best practices identified in the literature review. The roadkill hotspot analysis identified roadkill hotspots in Idaho on major roadways. A roadkill hotspot analysis is the first step to determining locations for wildlife crossings. This hotspot analysis is the basis for a site prioritization for future wildlife crossing locations in Idaho.