A deer leaps in front of a car at dusk, staring into the headlights – just before the car brakes slam down. This situation represents an everyday occurrence and poses an overlooked danger to both motorists and animals, with over a million crashes reported in the United States annually.
Wildlife-vehicle accidents result in hundreds in human fatalities, thousands of dollars in injuries, billions in property damage and even more in lost productivity. While some states have enacted rules and infrastructure to help, a large gap in prevention remains. Historically, isolated measures such as roadside fencing do see a reduction in roadkill, but this “band-aid” fix fails to address habitat fragmentation, leading to an increased risk of inbreeding and extinction. This may appear to be an environmental issue at surface level, but it extends to be a major infrastructure and public safety concern.
Animal crossings, which are built as overpasses and underpasses of roadways allow animals to cross sides safely. When complemented with fencing to gear animals in the correct path, they allow drivers to pass with fewer risks. Crossings easily integrate with current existing road design standards set by the American Association of State Highway and Transportation Officials since they effectively direct animals away from traffic. Still, they must be specifically designed to fit in with the environment and road itself. Underpasses are designed with drainage systems and specific dimensions to allow for more uninterrupted water flow, and overpasses usually have sound and light barriers to minimize any disturbances. Because unnatural, dramatic steep slopes are noticeable to animals, slight slopes are ideal and can account for footprint and erosion control.
These organic pathways have recently seen more attention and investment. In 2021, Congress passed the Wildlife Crossings Program, part of the Bipartisan Infrastructure Law, aimed at improving the network of wildlife crossings. The approval of $350 million for construction projects is a crucial step in acknowledging roads as a barrier for wildlife. However, funding is currently limited as state demand far exceeds the few rounds of federal grants, meaning a constant and continued bipartisan effort is necessary.
Practically, safe passages for wildlife have turned out to be measurably successful for both people and animals. In Banff National Park, for example, wildlife-road crashes declined by 80 percent after the establishment of a crossings network along the Trans-Canada Highway. In Washington, the investments have lowered crashes up to 90 percent. Colorado saw a 92 percent decrease after the completion of the Highway 9 project.
These natural-based crossings take a design that involves the intersection of engineers, ecologists, transportation agencies, and legislators. The Animal Road Crossing (ARC) initiative is a good instance of this collaboration. Their process starts with tracking animal movement, finding areas of conflict, and analyzing landscape characteristics. Civil engineers construct the structures so that a wide area of grass and plants are tactfully positioned to follow the natural migration route. To keep up with maintenance funding, policymakers may partake in private-public partnerships, as California relied on to construct the Wallis Annenberg Wildlife Crossing.
One of the challenges is ensuring that animals use these crossings. While critics have questioned its usefulness, motion-sensitive cameras consistently show wildlife adoption within weeks of properly designed, intuitive crossings. Further, site selection is a key factor to consider. Crossings need to be placed where animals actually travel, which is to follow natural terrain and migration patterns. Misplaced structures risk being underused or destroyed, which results in unnecessary taxpayer waste. Strategic placement preserves wildlife connections to larger habitats, encouraging survival of species, or genetic diversity, and healthier populations.
Many may write off these crossings as amenities we cannot afford. However, cost-benefit analyses show that wildlife crossings are smart investments. For each dollar spent, communities receive almost three dollars in long-term savings. They save on reduced crashes, lower insurance rates, less emergency response, and fewer repairs on the road. Most of the crossings pay off within a decade, particularly when constructed in high-collision zones. This return on investment has been shown in several states and cities, where yearly savings per crossing yield from $235,000 to $443,000. Crossings can also precipitate increases in revenue for surrounding communities as parks, forests, and rural areas become more attractive as tourist destinations. Crossings support natural processes like crop pollination, clean water filtration, and healthy soil quality that benefit agriculture and farms beyond the highway.
Continued investment in wildlife crossings will strengthen our ecosystems, reduce long-term costs, and improve safety. While these crossings may seem like an expensive investment that does not directly serve people, they pay for themselves in the long-run and create value for motorists, farmers, tourists, and more.
Written by Daryoush Jamkhu Public Policy Intern
The Alliance for Innovation and Infrastructure (Aii) is an independent, national research and educational organization working to advance innovation across industry and public policy. The only nationwide public policy think tank dedicated to infrastructure, Aii explores the intersection of economics, law, and public policy in the areas of climate, damage prevention, eminent domain, energy, infrastructure, innovation, technology, and transportation.