Professor making roads safer with animal overpasses
Roads have fragmented Utah’s landscape and Utah State University researchers are working to create safe passages to keep animals from becoming roadkill.
College of Natural Resources Professor John Bissonette, who oversees research done through the U.S. Geological Survey, said roads act as a barrier to animal movement across the landscape.
An estimated 2,100 vehicle accidents involving deer occur yearly in Utah, though Bissonette said he thinks the real figure is much higher. The effects roads have on wildlife aren’t limited to animal-vehicle accidents only, however. Animals unable to cross roads can suffer from isolation, which can lead to smaller populations and in some cases can cause endangered species, he said.
To avoid such scenarios, passages designed specifically for animals’ needs were developed to allow wildlife to cross roads and highways safely. Utah is home to many wildlife passages, including the first wildlife overpass built in North America, said USU researcher Patricia Cramer. The 22 foot wide overpass near Beaver, Utah, was built in 1975 and is one of only four similar structures in the United States today.
All other passages are tunnels that go beneath roadways, allowing deer and elk to pass, though the majority serve smaller animals like foxes and turtles, even though “the big animals get all the attention,” Cramer said.
Lewis Wight, a sophomore majoring in aerospace engineering, said he has hit “a lot of opossums,” and a skunk once. He said his main concern with vehicle-wildlife accidents are those involving deer or cattle, as they have the potential for human injury or death.
“[The passages] are good for bigger animals,” he said.” It keeps them off the interstate.”
Sardine Canyon has four underground wildlife tunnels, but the underpasses alone don’t solve the problem. Fences must be constructed in addition to the tunnels to prevent animals from crossing the road, as well as to guide them toward the passages, Bissonette said. Should a deer somehow get onto the fenced roadway, one-way “escape ramps,” allow them to exit.
Underground passages like the ones in Sardine Canyon are made from concrete or corrugated metal pipes about 15 feet in diameter. Bissonette estimated the cost of installing a passageway under an existing road to be as much as $2 million. Planning is already in effect to install passageways under Route 6.
Bissonette quoted author Richard T.T. Forman in saying that roughly 20 percent of U.S. land surface has been occupied by roads, parking lots and buildings.
“The message there is that roads have had an impact,” Bissonette said.
When many of the roads were constructed, thought for livestock and water drainage was usually all that was planned for, Cramer said. Some overpasses for tractors and cows have been used by wildlife, as well as water drainage culverts. While some animals use them, they are not ideal, or even considered wildlife passages unless they are altered to be more natural.
There are two ways of installing passageways: at the time of the road installation and during road refurbishment. Constructing a passageway at the time a road is built can cost between $1 million and $1.5 million, though he said the cost is “highly variable.” Putting one in during roadwork can cost closer to $2 million, Bissonette said, depending on the terrain.
Two tunnels were built along I-70 near Beaver after hunters struck up conversation about the roadkill in the area.
“The sportsmen really got upset because they were seeing a lot of mule deer on the road,” Bissonette said.
They talked to the Department of Transportation, as well as Fish and Wildlife and rallied local support. It took a number of years, he said, but eventually two underground passageways were installed with exclusion fencing, and since then, there have been fewer deer-vehicle accidents. The main way to determine the effectiveness of the passage is by monitoring its use. Video cameras placed in some culverts have recorded animals walking through them, Cramer said, and animal tracks have been found in them as well. This is proof Cramer said she finds very satisfying.
About 200 people are killed nationwide every year from animal-vehicle accidents, and about four die yearly in Utah, Bissonette said. A dangerous aspect of animals crossing roadways for which there is no data collected, he said, is the number of accidents caused by people who swerve to avoid hitting an animal, resulting in a rollover.
Bissonette compared an animal’s experience to that of a human crossing Main Street during rush hour at an intersection with no crosswalk. “It’s a dangerous proposition,” he said.
The financial aspect of the accidents is staggering, as well. The 13,020 deer-vehicle accidents that occurred in Utah from 1996 to 2001 cost an estimated $45,175,454, according to Bissonette’s research, which factored in injury costs, death costs and vehicle damage, with each crash costing $3,470. The Federal Highway Administration placed the value of a human life at $3.1 million dollars.
It doesn’t take long to make up the cost, he said.