News & Media
A Simple Concrete Bridge That Could Save America’s Wildlife
Jurors in the first-ever international competition to design a wildlife-safety bridge announced a winner on Sunday: Landscape architects Michael Van Valkenburgh Associates (MVVA) and the construction firm HNTB for a foliage-covered pre-cast concrete span that, in the architects’ telling, could rise over roads anywhere cars and animals collide, whether the highways of West Virginia or a major interstate in Colorado.
The jury’s selection conveys a clear message: When it comes to solving America’s reported $8 billion roadkill problem, simplicity reigns supreme. “The real genius of the design is in the structure,” says Robert Rock, a senior associate at MVVA (the same firm that’s redesigning the grounds of the St. Louis Arch). “Pre-cast concrete is readily available and there are many re-casters across the nation, which it makes it something that can be built almost anywhere right now.”
There’s little doubt that overpasses, where animals can safely cross highways, are crucial to preventing wildlife-vehicle crashes. As the New York Times reports, one such bridge in Canada has slashed accidents 80%. The question, then, is a matter of design. What type of bridge works best? How can it be done cheaply? Thus was born the ARC: International Wildlife Crossing Infrastructure Design Competition, which asked architects and engineers to design a bridge for a stretch of I-70 in Colorado, near Vail, that’s notoriously dangerous to the region’s furry friends. The purse: $40,000.
By selecting Michael Van Valkenburgh Associates, jurors showed that they’re less interested in fancy designs (one runner-up suggested using the same type of structural frame used in skyscrapers like the Gherkin and the Hearst Tower) and even strict environmental considerations (another, which we wrote about here, wanted to build a bridge out of beetle-killed local wood). Instead, they threw their support behind a tried and true construction method, one that isn’t specific to any part of the country.
MVVA proposes joining strips of pre-cast concrete — each 8 feet wide — to create a bridge a bit bigger than a football field. “Each module is identical,” Rock says, “so you can stack them to create any dimension you want. Some sites won’t need a crossing that’s 190 feet wide. Some sites may need 100 feet or 50 feet. By making it something that’s adaptable, we’re ensuring we can build whatever’s appropriate.”
The concrete is then covered in plants, trees, and other flora selected to mimic the environment, the idea being that the closer the bridge resembles animals’ natural surroundings, the more likely they’ll go galloping across (instead of in front of a car).
Rock says that a football field-sized crossing would cost $8.3 million; a bridge half as long would cost $3 to $4 million. By those estimates, you could build at least 1,000 wildlife bridges and still spend less than America does each year on vehicle-animal collisions.
The issue, of course, is whether anyone’ll cough up the dough to get these things built. (The design contest was mounted by a nonprofit, not an official agency with the power to approve construction and funding.) “The goal of the ARC competition was to make this about public outreach and to help people understand the gravity of the situation,” Rock says. “It’s not something that’s solvable overnight. But this proves that there are solutions.”