Good investment Underpasses and other measures to avoid wildlife collisions pay off, says a U of C study
If you drive a lot of country roads or big highways, sooner or later you’ll hear the thud of your vehicle hitting a bird or an animal and feel the guilt of killing or injuring an innocent creature. If you hit a big animal, like an elk or a moose, you or your passengers could be killed or injured.
Aside from that, there’s vehicle repair and other costs associated with wildlife accidents.
They’re substantial, according to a study by the Mistakis Institute at the University of Calgary. It estimates the immediate per-accident costs of human injuries and fatalities, vehicle repairs, towing costs, emergency attendance at scene, accident investigation, carcass removal and the hunting value of the animal at $6,617 for deer, $17,485 for elk and $30,760 for moose (in 2007 dollars).
That makes underpasses and other measures to keep wildlife off the highway a good investment, says Tony Clevenger, a lead scientist on the study. He’s a specialist in road ecology with the Western Transportation Institute at Montana State College of Engineering, which focuses on rural transportation issues.
“This is the first time a study in North America has shown the savings realized by building wildlife crossing structures on a major roadway,” Clevenger said.
The study looked at the number and cost of wildlife-vehicle collisions on a 38-km stretch of the Trans-Canada Highway between Canmore and Highway 40 to Kananaskis Country, but focused on a three-kilometre stretch where an underpass with three km of deer fence was installed in 2004.
The researchers figured the average cost of wildlife collisions before the underpass and fencing were installed was $128,300 a year. After installation there were 80 per cent fewer collisions, reducing the cost to about $17,500 a year.
The average number of deer killed dropped from 30 to eight a year, moose from five to zero and elk from 22 to three. Coyote, wolf and cougar collisions dropped to zero from five, two and one respectively. However two black bears and two beaver a year were killed where few had been killed before.
Clevenger suggests installing an underpass pays off for any stretch of highway where wildlife collision costs average more than $18,000 — 3.2 deer-vehicle collisions — a year. But he says an underpass alone isn’t enough and it isn’t always the best way to keep wildlife off the road.
Identify hot spots
The first step is to find the hot spots where animals most often cause wrecks. Clevenger says this is not easy, as there’s no organized data. He suggests Alberta Transportation should collect systematic information on both roadkills and injury, as injured animals can leave the highway and be out of sight of cleanup crews.
Clevenger maps roadkill hot spots and overlays the map with maps of the geography and wildlife activity and habitat areas. He prioritizes potential sites for underpasses or overpasses by the importance of connecting habitat areas, which are particularly important for carnivores that need big territories. He also considers development and land ownership, to avoid investing in an area where development is likely to drive wildlife away.
Clevenger says underpasses and fences are not the only collision-prevention strategy. Land management, fencing design, and adaptation of existing highway structures can help wildlife passage. At one hot spot in the stretch of highway east of Banff Park, animals can cross under the highway beside a bridge. Adding fill and vegetation for cover along with fencing to funnel animals in that direction would push them to avoid the highway. In another spot a drainage culvert could be retrofitted to the size Clevenger says is the minimum for an underpass — four metres high and seven wide.
The traditional static signs such as “elk crossing” cut collisions by 26 per cent, and moving wildlife out of an area by 50 per cent. Locating salt licks away from the highway or de-icing the highway with non-salt products may help cut collisions with ungulates.
Electronic animal detection systems linked to changing signs that warn motorists of the presence of animals on the road cut collisions with wildlife by 85 per cent. Clevenger is hopeful that electromats will be more effective than cattle guards in keeping animals off highways. The team is also looking at strategies to cut wildlife vehicle collisions in Foothills and Crowsnest sections of Highway 3. They have volunteer motorists reporting where on the highway they see wildlife.