It’s estimated that one million animals are killed every day by collisions with vehicles – and that’s just in the United States, which is not unique in this regard. The scale of the carnage is almost incomprehensibly vast; what might be done to stop it? And could reducing roadkill’s toll ultimately save people money?
An instructive story comes from central Arizona, where in the early 2000s the state’s Department of Transportation reconstructed an 18.6-mile-long stretch of highway that crossed a well-traveled elk migration corridor. Unlike most such efforts, the project included multiple underpasses and bridges for wildlife.
Requests from biologists for elk-proof roadside fences that would channel animals into the crossings were denied, though, and elk preferred to walk straight right across the highway rather than use the crossings. Elk-vehicle collisions actually increased.
In 2004 the state’s Game and Fish Department secured federal funding to do the fencing right. They built an 8-foot-tall fence along the most heavily elk-traversed section of the highway. Yet whereas one end of the fence terminated in a wildlife crossing, the other simply stopped in open terrain. Elk reluctant to use a bridge or underpass could walk along the fence until it ended and then enter the highway.
The biologists helped install a video system that analysed real-time footage of the landscape near that end of the fence. When animals approached, sensors triggered warning signs along the highway, alerting oncoming motorists to their presence – and, as researchers led by Arizona Game and Fish Department biologists Jeffrey Gagnon and Norris Dodd describe in the journal Human Dimensions of Wildlife, it worked wonderfully.
Drivers lowered their speeds and were quick to tap the breaks. In the nine years following the upgrade, a total of seven wildlife-vehicle collisions occurred. Prior to the upgrade, that stretch of highway averaged 9.33 collisions each year.
Drawing on other studies that estimated the average per-collision cost of car damage and human injury, Gagnon and Dodd’s team calculated that the new system saved $149,655 annually. “Over the 9 years following fence modification, the project accrued benefits exceeding $1.3 million,” or more than twice what it cost to install, they wrote.
Economic advantage
The new study isn’t the first to show that wildlife-friendly road infrastructure can dramatically reduce collisions. The detailed data and in-depth cost analyses are especially compelling, though, and suggest the considerable benefits of using these tools. After all, aside from the animal toll, wildlife-vehicle collisions annually “cause an average of about 200 human deaths, 30,000 injuries, and economic impacts exceed $8 billion,” write the researchers.
Much of that might be averted – and it would even make economic sense to do so. Why, then, are fences and animal crossings and automated detection systems not a default part of road construction and management, at least in particularly collision-prone areas? It’s a matter of funding, say Dodd and Norris.
These systems might save money in the long run, but up-front costs are considerable and the necessary political will is lacking. According to Dodd, funding for projects like his has actually decreased. It was tied to a tax on gasoline, and increasing fuel efficiency means lower revenues. “Until Congress bites the bullet,” said Dodd, “our highway infrastructure will crumble and degrade while conflicts go unaddressed.”
When the conflicts are finally addressed, improvements should soon follow. Dodd described working on habitat restoration projects where the results are not visible for decades. “In the arena of wildlife-highway conflict resolution,” he said, “the results are often immediate and tangible.”
This article first appeared on Anthropocene Magazine.