This publication features answers to the most common inquiries and misconceptions regarding wildlife-vehicle collisions and the proven success of wildlife crossing infrastructure in solving this ubiquitous problem.
The costs of wildlife crossings are diffused across property damage, health care, road maintenance, and loss of wildlife. The estimated cost of wildlife-vehicle collisions to Americans is more than $8 billion annually (in 2007 dollars).
Wildlife-vehicle collisions result in more than 200 human deaths and 26,000 human injuries annually.
An estimated 1-2 million crashes occur annually between motorists and large wildlife in the United States – or about one every 26 seconds. This figure does not include the tens to hundreds of millions of smaller animals killed each year in collisions that do not result in human injury or property damage, and thus are typically not reported or counted.
A wildlife crossing is a structure designed or retrofitted to facilitate the safe movement of wildlife across a roadway.
The two main objectives of wildlife crossing mitigation efforts are to: reduce vehicle collisions involving wildlife that lead to human deaths and injuries, property damage and wildlife mortality and to reconnect habitats for wildlife populations.
There are two main types of wildlife crossings. Structures that allow wildlife to pass above a roadway are referred to as overpasses, and structures that allow wildlife to pass below a roadway are called underpasses.
Although installing fencing to prevent wildlife from entering roadways may prevent collisions, it also blocks animals from accessing important habitats and resources necessary for survival.
It depends! Each crossing is designed to serve the target animal for a specific location or to accommodate the majority of wildlife that reside in or move through an area. Wildlife crossing structures also may be designed from a motorist safety standpoint for target animals, such as large ungulates like moose, elk, or deer, or for species with the highest conservation concern.
Wildlife crossing structure design, size, and placement influence how different animals respond to structures. Some species prefer large, open structures, while others prefer more enclosed structures with less light. Wildlife crossing structures designed for multiple species maximize biodiversity conservation.
Wildlife crossing structures are typically constructed in combination with fencing. Fencing keeps animals off roadways and funnels them to structures, greatly enhancing the effectiveness of wildlife crossing structures. In contrast, fencing alone (without crossing structures) creates a barrier that can keep animals away from important habitat areas, potentially jeopardizing their survival.
There is a rich body of research on the effectiveness of wildlife crossings. One of the world’s longest running efforts is a 17-year study that monitored 23 out of 40+ crossings in Banff National Park in Canada.
During the course of that study, researchers documented more than 185,000 crossings by 11 large and medium-sized animals, including grizzly and black bears, cougar, Canada lynx, coyotes, wolves, deer, elk, bighorn sheep, moose, and even wolverines. You can read a summary of the report here.
When properly designed and sited, wildlife crossings with fencing have been shown to effectively reduce WVCs by up to 97%. This means that a road that saw 100 crashes last year could see as few as 3 after mitigation.
Wildlife crossings with fencing have been shown to effectively reduce motorist crashes involving wildlife by up to 97%, reducing human deaths and injuries, and making our roads safer for people. Mitigated roadways may also create a sense of motorist wellbeing and lessened worry when driving. When surveyed, the public repeatedly has placed an intrinsic value on public investments where our natural resources are protected and preserved, especially when doing so also meets the dual needs of safe roadways for both people and wildlife.
By reducing wildlife-vehicle collisions (WVCs), crossing structures also reduce the societal costs of those crashes, including lost lives, injuries and property damage. Where the total cost of such crashes is higher than the total expense of building a wildlife crossing structure, it actually costs society less to solve the problem of WVCs by building a crossing, than it costs to do nothing.
Wildlife crossing structures and fencing allow wildlife to safely move across highways, which helps ensure that their local and regional populations remain stable.
With 1-2 million large wild animals killed by vehicles every year, wildlife mortality due to roads can significantly lower population sizes, and potentially jeopardize their survival in the longterm, especially for smaller wildlife populations. By physically separating wildlife from traffic, crossing structures also protect individual wild animals from death or injury.
Roadways can act as barriers that pen wildlife into smaller fragments of land, limiting their access to water, food, mates and other life needs. These smaller populations may suffer from a smaller gene pool and less gene flow. Wildlife crossing structures allow individual animals to disperse and mate with individuals in other populations, increasing gene pool size and flow.
Unlike many problems we face as a society, we have proven solutions to solve this problem today. There is simply no time like the present to take on the challenge of protecting the 200 drivers that will die this year as a result of a collision with wildlife, not to mention the tens of thousands of injured motorists, billions of dollars in property damage, and millions of wildlife deaths.
The answer is complicated. First, most people either don’t know about crossings or they don’t know that they work. Second, it’s not unusual for transportation agencies to think that it’s not their job to save wildlife, or for wildlife agencies to think that it’s not their job to fix roads. Finally, it’s a lack of funding, which means that wildlife crossing projects compete with bridges, pavement and potholes for scarce transportation dollars.
Although competing priorities do exist, and new technologies, such as on-board pedestrian, bicyclist and animal detection systems and self-driving cars, may help greatly in the coming decades to reduce crashes with large animals, they are unlikely to address medium and small-sized wildlife. These fixes also won’t happen overnight, and indeed it could be decades before these new technologies exist in even half of the cars on the road. And while increased deployment of mass transit systems will help reduce the number of cars on our roads, those systems are unlikely to eliminate the 89% of wildlife-vehicle collisions estimated to occur on two-lane roads.
The U.S. Congress is in the process of reauthorizing our nation’s federal transportation law, which expires on September 30, 2021. Please consider calling up your federal Representative and U.S. Senators to let them know this issue is important to you, and that you support dedicated federal funding for wildlife crossing structures to make our nation’s roads safer for people and wildlife.
A number of states already have existing coalitions of people working to reduce motorist crashes involving wildlife. Search online search to see if your state or community has a local coalition you can join. If not, consider starting a group of your own!
A number of organizations have developed curricula with fun and educational activities for grade school and middle school students. Please reach out to ARC Solutions to learn more.