Wildlife Crossings over Roads: Designing Transportation With Nature

As urban development continues to expand, the natural habitats of wildlife are increasingly fragmented by roads and highways. This is not a new phenomena, but there are innovative ways that planners and traffic engineers are working to mitigate these harms, which we should note, not only endanger animals but also poses significant risks to drivers. Wildlife crossings, such as bridges and tunnels designed specifically for animals, offer a promising solution to these challenges.

The Wyoming Department of Transportation partnered with the state wildlife agency and nonprofit groups to create a series of wildlife crossings, a concept lauded by environmentalists and transportation officials alike. (Image via Patch)

Simply put, wildlife crossings are structures that allow animals to safely cross over or under roadways. These can take the form of overpasses, underpasses, tunnels, and viaducts, often covered with vegetation to blend into the natural landscape. The idea is to provide a safe passage for animals, reducing the likelihood of vehicle-animal collisions and helping to maintain ecological connectivity. In the above photo, a crossing over US 191 in Wyoming allows mule deer to safely cross over both the highway, but also railroad tracks, which also have negative effects for animal crossings, albeit less so than highways.

I've been aware of wildlife crossings for some time, and even posted about some back when we maintained a Facebook page, however, the idea of them reentered my mind after listening to a podcast called Lifeworlds, which in addition to this topic, is an incredible podcast hosted by Alexa Firmenich, who is a climate journalist and investor, in addition to numerous other hats. I cannot recommend her work enough. In this particular episode, she discusses the concept of wildlife crossings being integrated into future road projects, as there is expected to be an increase of 25 million km of new roads across the world over the next thirty years, many of which in new areas across the world where animal populations have never observed roads before. 

A great article showing many videos of animals using crossings came from the New York Times in 2021, How Do Animals Safely Cross a Highway? Take a Look.

One quote in the podcast by guest Nina-Marie Lister really spoke to me, "we have socially and culturally made acceptable that roadkill is a part of everyday movement, when in fact if you step back from it, does not have to be that way at all. There's a kind of stunning acceptance of death on the road as being the cost of modern society's movement." Sadly, this seems to apply to humans as well to a lesser extent.

"Wildlife overpass spans US 93 in Montana. One of numerous engineered interventions included when the highway was widened in the early 2000s on request by the Confederated Salish and Kootenai Tribes to mitigate the road’s impact on landscape and near-by communities.
Photo credit: Montana Department of Transportation." (Caption via High Plains Stewardship)

This blog is exploratory, but it is also something that is closer to me than some may realize. The first car I ever bought that was brand new was a Chevy Cruze in June, 2013. It was the first and last Chevy I'll ever buy, but I digress. After 9,000 miles behind the wheel, I took it out for a late November drive, only to hit a deer crossing I-88 during its mating season.

This was the result:

The collision with the deer shorted the battery, which sparked a fire. I was not hurt as I was able to quickly escape the vehicle, but I remain shaken to this day from the outcome.

A Chevy Cruze in its alternate-Silent Hill form.

My reason for bringing this up is not to say that a wildlife crossing would have prevented this accident; but to highlight the dangers that wildlife are to motorists. We shouldn't need reminding of how dangerous we are to them; we've all seen roadkill before, there is no need for me to show it again. 

Wildlife crossings significantly reduce the risk of animals being hit by vehicles. For instance, in areas where these crossings have been implemented, there has been up to a 80% reduction in vehicle-animal collisions, according to the World Wildlife Fund. This not only saves the lives of animals but also reduces the risk of injury or death for drivers and passengers

However, that is not the only benefit of crossings, as these structures help reconnect fragmented habitats, allowing animals to access essential resources such as food, water, and mates. This is crucial for the survival and genetic diversity of many species.

One of the largest wildlife crossings in Banff National Park. (Ross MacDonald Photo via the Guardian)

Over time, animals learn to use these crossings, and this behavior is often passed down to subsequent generations, further enhancing their effectiveness. In addition to the crossing itself, many crossings have linear fences on either side of the crossing to help animals navigate towards it in the initial development, and by making these crossings resemble the natural world as much as possible, animals quickly adapt to the new reality and largely do not seek to cross the road to get to the other side.

Banff National Park is home to one of the most extensive networks of wildlife crossings in the world, including 44 wildlife underpasses and six overpasses. These structures have been highly effective in reducing wildlife-vehicle collisions and maintaining ecological connectivity. There have been examples of positive effects worldwide, and places like the The Netherlands have over 600 crossings designed to protect species such as badgers, elk, and deer, among other species.

Of course, positive benefits to human, animal and ecosystem health are not the only benefit. Fewer collisions mean lower costs related to vehicle repairs, medical expenses, and insurance claims. In the United States alone, vehicle-animal collisions cost approximately $8 billion annually according to the WWF.

Wildlife crossings are a vital tool in mitigating the negative impacts of roads on wildlife and human safety. By investing in these structures, we can create a safer environment for both animals and drivers, ensuring that our roadways do not become barriers to the natural world.

I hope this blog provides a comprehensive overview of the importance of wildlife crossings. If you have any specific aspects you’d like to explore further, feel free to let me know!

Thanks as always for reading!