Deer were the most common animals involved in vehicle collisions, each costing about $9,000 on average. Roughly calculated, each structure saved $235,000 to $443,000 every year. Similar evidence has been found through studies conducted in North Carolina, Utah, and Wyoming by other researchers.
“From a driver’s 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,” said Sugiarto in the press release. “Decreasing accidents would further reduce unnecessary trauma and also save lives in addition to saving money.”
The study relied on official reports required only when the damage is $1,000 or more. Insurance claims could possibly reveal more data and benefits of these structures.
The study also revealed information about animal behavior. Camera traps showed that deer liked to use bridge crossings while predators like bears preferred underpasses.
The results of the study were published in the journal Transportation Research Record.
This paper examines whether wildlife crossing structures reduce the number of wildlife–vehicle collisions. Using Washington state crash data from 2011 to 2020, I employed a difference-in-differences methodology at the year level on each of 13 observed wildlife crossing structures in Washington. The treatment area consisted of wildlife–vehicle collisions within 10 mi of a wildlife crossing structure, and the control area included wildlife–vehicle collisions that were 60 to 70 mi from the same wildlife crossing structure. I found evidence that wildlife crossing structures resulted in one to three fewer wildlife–vehicle collisions on average per mile per year. The marginal treatment effect also held within a 5-mi treatment area, a 15-mi treatment area, and when controlling for the presence of other structures within the baseline of a 10-mi treatment area. However, the collision reductions were more consistent among wildlife bridges than culverts, suggesting that not all wildlife crossing structures have the same effect in reducing accidents involving wildlife. Using a back-of-the-envelope approach, each wildlife crossing structure yielded annual benefits of $235,000 to 443,000 in 2021 U.S. dollars.