Animal-vehicle collisions are dangerous to both humans and animals. Most of us have been driving or riding in a car when suddenly a deer darts out in front of us. The Federal Highway Administration reports one to two million collisions between cars and large animals occur in the U.S. every year. Solutions like “Deer Crossing” signs are inexpensive but not highly effective.
Is there a better way? America is turning to other countries who have successfully used road ecology practices for years. Engineers and ecologists are working together to create bridges and underpasses—not just for cars and pedestrians, but solely for animals.
“The cost to put in these over bridges for animals is very expensive,” says Marcel Huijer, senior research ecologist for the Western Transportation Institute in Montana. “But, the cost of not putting them in is much higher.”
WHY DOES AN ANIMAL CROSS THE ROAD, ANYWAY?
We’ve all heard the joke, “Why did the chicken cross the road?” Well, it’s no joke that creatures do indeed need to get to the other side. Animals must cross roads to mate, or to find food and water. For many, these migration route patterns have been passed down for generations.
Animals are truly creatures of habit. Using GPS and cameras, road ecologists track animals' natural travel patterns. Next they look at statistics of roadkill along these heavily traveled routes. This data determines where the safe passages should be built. “I’d like to get to the point where we are proactive instead of reactive,” says Huijer. “Before the roads are even built, ecologists and transportation could work together to plan these structures.”
DESIGNING SAFE CREATURE CROSSINGS
One size does not fit all. To determine what action to take, road ecologists first look at how wildlife use existing structures. They ask questions about how the animals travel under, over, around, or through. Bobcats might prefer a round culvert, or tunnel, to cross safely. Taller deer, on the other hand, will require bridge extensions to cross under highways.
Wildlife overpasses prove to be the most successful for all species. An animal overpass looks like one built for automobile traffic, but instead of asphalt, these often have grass and trees. The overpass built across Trans-Canada Highway has proved successful for Banff National Park in Canada. Monitoring has shown elk, deer, lynx, coyotes, wolves, wolverines, and bears using the overpass for safe crossing.
Banff’s underpasses and fencing, along with two wildlife overpasses (built in 1996), have reduced animal-vehicle collisions in the area by more than 80%, and over 96% for elk and deer alone, says Canada’s Discover APEGA.
ANIMAL CROSSINGS—COMING TO A HIGHWAY NEAR YOU?
Over 1,000 designated animal crossings are in the United States today. You might not be aware of them or be able to see them. The Florida Department of Transportation’s underpasses provide safe passage for the state’s endangered panther. In Amherst, Massachusetts, tiny underpasses allow salamanders to safely cross.
Other animal crossings are more apparent, like the massive Robert L.B. Tobin Landbridge. Built in Austin, Texas, in 2022, it is the largest in the country, costing $23 million. According to The New York Times, Wyoming’s land bridge over Highway 191 allows mule deer and pronghorn to keep their age-old migration paths and has dropped collision rates by around 90%.
State transportation departments are mainly responsible for animal crossings. The result is usually a partnership between landscape architects, engineers, and government transportation services.
Private fundraising is sometimes used for future creature crossings. That’s the case with Safe Passage: The I-40 Pigeon River Gorge Project. Nonprofit organizations like the Great Smoky Mountains Association are working to protect the animals in the heavily-trafficked region around the Great Smoky Mountains National Park.
Money is only part of the equation. The Creative Services Director of the nonprofit Great Smoky Mountains Association also wants to educate children. In her middle-grades book, "A Search For Safe Passage," Frances Figart uses storytelling and facts to inspire knowledge about animal crossings. Tireless, combined efforts of many are ensuring safe passage for all creatures, great and small.