Wildlife road crossings can pose a huge risk to both motorists and animals. According to the Federal Highway Administration (FHWA), there are more than one million wildlife-vehicle collisions in the US per year, costing more than $8 billion annually and resulting in hundreds of (human) fatalities.
Roads also pose a significant issue for animal conservation efforts. A Nevada Department of Transportation study found that roads often cut animals off from food, habitat, and genetic diversity, and a 2008 study from the FHWA noted that roads often pose a risk to endangered or threatened species.
In Washington County, Minnesota, local transportation officials have taken steps to mitigate some of these risks. Highway 4, located just south of Washington County’s Big Marine Park Reserve, was a well-known site for instances of turtle roadkill—likely due to its close proximity to a wetland complex. In 2014, with funding from the Minnesota Local Operational Research Assistance (OPERA) Program, the county installed a culvert tunnel underneath the road with a fence designed to funnel animals toward the tunnel.
“We’ve been really happy with it,” says Kevin Peterson, design engineer for Washington County public works.
There were fewer citizen reports of roadkill in the area after the installation, Peterson says, and a motion-activated camera has shown evidence of small mammals, amphibians, reptiles, and even Blanding’s turtles (a state-listed threatened species) using the tunnel. This was helpful not only for conservation reasons but also because it promoted safer driver behavior.
“People used to always stop and move turtles across the road,” says Dan MacSwain, natural resource coordinator with Washington County, “and that’s the big part of this project that doesn’t get talked about enough.”
Chris Smith, who worked on the project while with the Minnesota Department of Natural Resources and who now works as the protected species coordinator at MnDOT, says that prioritizing safe wildlife crossings can have a huge effect on human safety. However, he emphasizes that communities and transportation departments need to focus on safety measures that have been proven effective.
“I get contacted regularly by concerned Minnesotans that want wildlife crossing signs,” Smith says, “but these signs do not generally work and are not a good use of public resources.”
The most effective strategies—such as under- and over-passes—tend to be the most expensive, especially when scaled up to accommodate large animals such as deer. MnDOT has worked around this in the past by using fences to herd deer toward existing structures—such as bridges, culverts, and underpasses—but even that can prove costly.
“Cost is always an issue,” Smith says. “There’s only so much money going around.”
However, Smith says, it’s generally better to commit to an expensive, effective strategy than a cheap, ineffective one. He recommends tapping into local expertise—MnDOT, universities, DNR offices, or environmental nonprofits—for research on effective countermeasures and roadkill hot spots that need priority consideration. He also says wildlife road safety considerations should be worked into road engineering plans early in the process to save on cost and time.
Looking forward, Smith and MnDOT have been working with experts from the Minnesota Zoo to develop standardized fencing designs that prevent small animal species from crossing roads—something that can be readily worked into roadwork projects when there’s a known roadkill hot spot in the area.
The FHWA has also dedicated money from the Infrastructure Investment and Jobs Act of 2021 toward the Wildlife Crossings Program: a pilot program through which transportation agencies and local governments can apply for funding to work on wildlife safety projects.
“I think the Bipartisan Infrastructure Law really highlights this increasing public awareness and interest in this topic,” Smith says, “and it’s nice to see that there’s new money potentially available to highway departments to address some of these issues.”
—Sophie Koch, contributing writer