Over and under highway wildlife crossings are designed to help animals move safely across roadways. It’s an attempt to maintain animal movement and genetic connectivity. However, we are now learning about another benefit of these crossings.
A recent study published in the Transportation Research Record found that wildlife crossings in Washington state save approximately $235,000 to $443,000 every year per structure. The state has 22 wildlife bridges and underpasses.
The researchers found that every year, there are one to three fewer wildlife collisions per mile in a 10-mile radius around each wildlife crossing.
“Wildlife crossing structures not only benefit the ecosystem but may also improve road safety,” said study author Wisnu Sugiarto, an economics doctoral student at Washington State University.
Evidence suggests that other states, including North Carolina, Utah, and Wyoming, also experience fewer wildlife collisions due to wildlife crossing structures.
Sugiarto analyzed accident data from the Washington State Department of Transportation from 2011 to 2020 and information associated with 13 bridges and underpasses in the state. The study compared collisions before and after the crossings were built. He also analyzed another area in the state that never had crossings for a control.
The most common crossings are wide bridges and underpasses, with the bridges being much more expensive. Although bridges may be more expensive, they may also be more effective. Sugiarto found that bridges led to a more significant reduction in wildlife collisions because deer, the animal most likely to be involved in a crash, prefer bridges to underpasses.
Many wildlife collisions occur due to simple misfortune. The drivers often drive safely but happen to be in the wrong place at the wrong time.
“We often talk about things that we can and cannot control,” said Sugiarto. “From a driver point of view, they may choose to drive safely, but still, unfortunately, there are animals that cross the road, and they end up hitting them. This shows there’s something we can do about these collisions.”
The good news is that we may begin to see more of these bridges across the country in the future, thanks to the federal Infrastructure Investment and Jobs Act of 2021, which allocates $350 million to a Wildlife Crossing Pilot Program.