Roadkill causes problems beyond unsightly messes. The Federal Highway Administration estimates car-critter collisions cost taxpayers $8 billion a year, while further imperiling already endangered species.
A Minnesota public works department found a way to reverse the trend.
Highway 4 in Washington County is treacherous for local wildlife, especially turtles. On the south edge of the county’s Big Marine Park Reserve, turtles make the perilous crossing over the two-lane highway as they migrate between the wetlands where they spend their winters and the sunny, sandy slopes in which they make their nests.
Many have met their demise under the wheels of passing cars and trucks, and well-meaning pedestrians have been hit after stopping to help a turtle speed its way across.
Last year, the Washington County Public Works Department and other concerned parties came up with a solution: a tunnel under the highway just for wildlife. The department orchestrated the $50,000 project, which was funded by grants from the Minnesota Department of Natural Resources, the University of Minnesota, and Minnesota Herpetological Society.
“There’s an overlap of interests,” says county Park Manager Peter Mott. “The agency wants to keep this road safe, and the conservation folks want to make sure these turtles didn’t meet with untimely deaths on the roadway.”
In June 2014, department crews installed ACO Polymer Products Inc.’s AT500 Amphibian Guidance System (load Class A-D asphalt) and fences on either side of the highway to funnel wildlife toward entrances on either end. Slots in the top of the polyester-resin polymer concrete culvert enable water and light to enter.
It didn’t take long for the passageway to resonate with the pitter-patter of little feet. Motion-sensor cameras soon captured images of skunks, woodchucks, weasels, snakes, and mice walking, waddling, and wiggling through. When turtle migration season hit at the end of summer, the shelled nomads began their annual trek.
“Last August, our first snapping turtle come through,” Mott says. “This June, a lot more came through. So yes, turtles are using the turtle tunnel.”
Since the tunnel opened to animal traffic, the department says zero car-wildlife collisions have been reported. Additionally, the tunnel stood the trying test of a cold Minnesota winter freeze and ensuing spring thaw.
County staffers aren’t quite sure how or why critters know to use the tunnel. They just do.
“It’s got some kind of internal system that we don’t really understand,” Mott says. “It’s telling them they need to go that way.”
Jenni Spinner is a business writer who has covered a wide range of industries, including public works, construction, food production, and packaging. E-mail firstname.lastname@example.org.