The Bow Valley Gap Wildlife Overpass, designed by our firm, DIALOG, and completed in 2024, is a modest but innovative intervention designed to reconnect disrupted wildlife corridors in this heavily trafficked region. It’s also the first wildlife overpass in Canada constructed outside of a national park. Quietly embedded in the landscape, this simple structure supports more than animals—it carries the idea that suburban and exurban infrastructure can be both well engineered and contextually sensitive.

Of course, crossings don’t just magically appear out of the mist like a clueless cervid. Infrastructure costs money. A study published in 2021 by Washington State University researcher Wisnu Sugiarto found that the average cost of a wildlife crossing ranged from $500,000 to $6.2 million, depending on the length, materials, and geographic complexity of the project. 
Some would call that a bargain. “There’s virtually no other transportation infrastructure that’s going to get you this kind of return on investment,” says Renee Callahan, executive director of ARC Solutions, a nonprofit organization that promotes the development of wildlife crossings. 
Sure, ARC is an advocacy group, but the research backs up its claims. These crossings netted annual savings of $235,000 to $443,000 per structure in terms of collisions prevented, according to Sugiarto’s study.
The near-term outlook for wildlife crossings is favorable. The infrastructure bill passed by the U.S. Congress in 2021 included $350 million in grant funding specifically for these projects. If all that money is actually spent on building new crossings, the U.S. could add somewhere between 56 and 700, which, according to Sugiarto’s math, would save at least $13 million annually — and as much as $310 million. 
That means the investment could pay itself off in less than two years, and you can’t put a price tag on the human and animal lives saved. It’s the rare transportation infrastructure win that anyone can applaud — whether they have hands, hooves, or paws.

Why do animals cross the road? Some are just migrating. Others seek food or mates. But whatever the case, they aren’t likely to pay much attention to traffic — and that can mean disaster. Every year in the U.S., an estimated 350 million animals and more than 400 people die in animal-car crashes. And even crashes that don’t claim lives still cost an average of over $4,100, according to insurers — which all adds up to billions in annual damages. 
That’s why animal crossings have become so popular. These specialized over- or underpasses allow wild animals — from wolves and bears to moose, deer, elk, and even butterflies — to pass safely. They’re typically covered with vegetation and terrain to make them more attractive to animals and may be fenced and off-limits to humans. According to one study, animals are 146% more likely to use one than a random stretch of road. Another long-term investigation showed that crossings reduced accidents by greater than 80%  annually.

Animal Overpasses Save Bambis … and Benjamins

The design and engineering firm Dialog led the structural engineering and landscape architecture of the overpass, which was funded by Alberta’s provincial department of transportation and is now the first wildlife overpass in Canada constructed outside of a national park. It’s in an area where reported vehicle collisions with deer, elk, coyotes, and grizzly bears happen 69 times per year on average. “The very rough rule of thumb is for every collision that is recorded or every carcass that is seen on the side of the road, you can usually double that number,” says Dialog’s Neil Robson, the overpass project manager and lead designer.

Located between Calgary and Banff National Park, this stretch of the Canadian Rockies is sliced in two by the Trans-Canada Highway, one of the busiest roadways in the province. That’s had deadly consequences for the area’s abundant wildlife, as well as the tens of thousands of people who drive through it every day. But now, after years of mounting wildlife-vehicle collisions, the danger to animals and humans is being addressed with a stunning new wildlife overpass.

The Bow Valley Gap wildlife overpass is a roughly 200-foot-wide cap over a four-lane highway, topped with soil and forest-like plantings that creates a bridge almost indistinguishable from the forest on either side.

This stunning wildlife overpass helps animals cross one of Canada’s busiest highways 

How creating wildlife crossings can help reindeer, bears – and even crabs

This article is more than 5 years old
Sweden’s announcement this week that it is to build a series of animal bridges is the latest in global efforts to help wildlife navigate busy roads

Every April, Sweden’s main highway comes to a periodic standstill. Hundreds of reindeer overseen by indigenous Sami herders shuffle across the asphalt on the E4 as they begin their journey west to the mountains after a winter gorging on the lichen near the city of Umeå. As Sweden’s main arterial road has become busier, the crossings have become increasingly fractious, especially if authorities do not arrive in time to close the road. Sometimes drivers try to overtake the reindeer as they cross – spooking the animals and causing long traffic jams as their Sami owners battle to regain control.

“During difficult climate conditions, these lichen lands can be extra important for the reindeer,” says Per Sandström, a landscape ecologist at the Swedish University of Agricultural Sciences who works as an intermediary between the Sami and authorities to improve the crossings.

This week, Swedish authorities announced they would build up to a dozen “renoducts” (reindeer viaducts) to aid the crossings and allow reindeer herds to reach grazing more easily.

Ever wonder if animals really use those bridges to cross highways? They do! And not because they’re following signs.

Combining fencing with over- or underpasses together helps wildlife stay safe. That includes large species such as grizzly bears and elk and smaller ones, such as western toads and salamanders.

The fencing is an important part of these crossings, as it helps guide and funnel wildlife to the right spot and keeps them off the road.

The overpasses in Banff National Park are landscaped with soil, plants and trees to help them look like surrounding habitat. The underpasses are low and darker, providing the cover some species prefer.