News & Media

For Wildlife, a Safe Highway Crossing

by Matthew L. Wald (New York Times Green Blog)
January 24, 2011

As I report in Monday’s Times, a nonprofit group has awarded a $40,000 prize to an architecture firm for the design of a bridge intended to carry wild animals across a major interstate in Colorado.

What’s so special about it? The answer, according to officials who set up the competition, is that bridges for animals are different from the ones that highway departments habitually build. Vehicle bridges are narrow and strong, typically able to support two, four or six lanes of heavy trucks, while bridges for wildlife will never have to hold more than a few thousand pounds of elk, deer or bears. But the wildlife bridges need to be inviting to the animals and preferably wider.

Wildlife crossings are an old idea, but most are culverts, or extensions of bridges that carry a highway over a river or stream. An exception is a bridge over the Trans-Canada Highway where it slices through the Banff National Park in Alberta, Canada.

The bridge in Banff is considered a success because it reduced the collision rate by about 80 percent. But the structure itself is not an ideal model for use elsewhere, according to the experts at ARC, the group that carried out the competition that ended on Sunday.

A Canadian researcher involved in the ARC competition, Nina-Marie Lister, called the bridge in Banff “a standard old Ministry of Transport bridge,’’ built strong enough to support heavy truck traffic even though there is no way for trucks to drive over it. (At either end is woodlands, not roads.) And while it has a “green toupee on top,” she said, it is not designed to blend into the landscape.

The winning design for the Vail site, by the firm Michael Van Valkenburgh & Associates, is four times wider than the bridge at Banff. Made of precast concrete panels that are snapped into place and covered with foliage, it is broad enough to allow for lanes that look like forests, shrubs and meadows.

Ms. Lister, a professor of design and urban planning at Ryerson University in Toronto who is spending a sabbatical year as a visiting professor at Harvard, described the bridge as “an entirely new type of infrastructure” whose design would reduce construction costs.

Animal-vehicle collisions themselves cost about $8 billion a year, according to ARC, and the number of collisions has been increasing. The National Safety Council counts about 100 human fatalities a year in vehicle collisions with animals, and the number of injuries to humans is much higher.

The competition, which ended on Sunday, attracted 36 submissions involving more than 100 architecture firms from nine countries.