Why did the turtle cross the road? Hint: it wasn’t just to get to the other side.
John Maerz, Dennis and Sarah Carey Distinguished Professor of Forestry and Natural Resources and a Josiah Meigs Distinguished Teaching Professor in the Warnell School of Forestry and Natural Resources, can tell you exactly why turtles cross the road: it’s because they look for raised areas in which to lay their eggs, and roadways are often graded higher than the surrounding land.
In fact, for almost every wild animal that crosses the road, there is a clear explanation: animals require varied land types and resources throughout their lives, and they have to travel to get to them. Whether it’s a turtle crossing the road to get to higher ground, or a wild turkey crossing the road to find a safer nest site, just as humans move to survive, so must animals.
However, why turtles and turkeys—and other wild animals, like white-tailed deer, coyotes and salamanders—cross the road is only one small piece of a much larger puzzle that UGA researchers are trying to solve: whether they can simultaneously prevent wildlife from getting hit by cars and reduce flooding on roadways by designing better roadway bridges and culverts.
While flooding and wildlife-vehicle collisions may not seem like a natural pair, smart design may help address both the problem of undersized culverts leading to flooded roadways and safe movement of wildlife.
It was a willingness to go after this win-win solution that earned the interdisciplinary team at the University of Georgia—including Maerz, Brian Bledsoe, the Director of the College of Engineering’s Institute for Resilient Infrastructure Systems (IRIS), and IRIS staff Zak Ruehman, Kevin Samples and Alejandra Gomez, as well as Warnell’s Nate Nibbelink, Gino D’Angelo, Travis DeVault, Michel Kohl, Jade Samples and Vanessa Terrell—the opportunity to work with the Georgia Department of Transportation (GDOT) to design these passages.
“This call for proposals was centered around how states could improve their decision making with regards to infrastructure projects that would meet multiple societal challenges,” Maerz said. “The three we focused on were: how can we improve the connectivity of landscapes for the passage of wildlife? How can we deal with shifting pressures on infrastructure to accommodate things like more intense storms and flooding. And then how can we improve safety, both for wildlife and humans on roads?”
However, there isn’t a simple solution to a suite of problems that costs the U.S. well over $10 billion annually. As Maerz put it, “Wildlife-vehicle collisions are a fairly intractable problem. Roads are pervasive–if you drop a pin randomly in the eastern United States, you’re going to be within half a kilometer of a road. Most animals do not exist in a landscape where any movement will not put them in proximity to roads.”
The pervasiveness of roads isn’t the only complicating factor. Researchers must also consider the unique needs of each species that they hope will use the wildlife crossings, the differences in designing urban versus rural road crossings (for example, multi-lane highways will require longer crossings than two-lane country highways), and whether these crossings could accidentally turn into, as Maerz put it, “meal conveyor belts for predators.”
So how do researchers go about trying to solve such a complex problem?
“It’s a multi-step process,” explained Bledsoe. “We’ll analyze where in the state of Georgia wildlife-vehicle collisions are concentrated and also where roadway flooding is an issue. After that, we’ll create a prioritization tool to help decision makers combine the many important factors involved in choosing the best sites for improved crossings.”
Finally, the researchers will design the crossings themselves, which will be meant to handle much larger amounts of rainfall without becoming flooded and to direct both aquatic and terrestrial wildlife to cross under the road, instead of over it. The design process will happen in consultation with GDOT engineers and ecologists.
The complexity of tackling a problem at this scale might be intimidating to some, but both Maerz and Bledsoe view it as an opportunity to work collaboratively and creatively with their colleagues—and even welcome the challenge.
“There are huge costs, injuries and deaths associated with wildlife-vehicle collisions and with flooding. I’m very motivated to help GDOT meet their goals of providing resilient infrastructure for the citizens of Georgia,” Bledsoe said of the project. “Not to mention it’s a complex problem that requires us to work across disciplines and integrate knowledge, which is always a good challenge.
Maerz echoed his sentiment. “Even though we have different expertise and come from different fields, we both draw inspiration from embedding learning in doing. And I think that’s what makes this partnership work so well–we see these as chances to learn and think about creative solutions, while still evaluating those solutions to see if they if they do what we think they should do.”
It isn’t the first time that Maerz has applied creativity and teamwork to a seemingly intractable wildlife-vehicle collision problem. In 2022, Maerz and his team found that certain times of day were deadlier for diamondback terrapins crossing the road along the Georgia coast—but that the traditional turtle crossing signs didn’t do much to help the problem.
Inspired by the flashing school signs that alert drivers to the times when children are present, Maerz worked with GDOT to design a new sign: a turtle crossing sign that flashed at the times that terrapins were most likely to be on the road.
Amazingly, the signs worked: they halved the number of turtles that otherwise would’ve been hit on the road.
It’s this creative, interdisciplinary approach that just may make Georgia’s roadways safer for both wildlife and humans. As Maerz put it: “We’re not going to be able to step in and prevent all wildlife-vehicle collisions or flooding throughout the state. But through creativity and collaboration, we can make a seemingly intractable problem slightly more tractable.”