To Keep Wildlife Off Roads and Trails, Wyoming Builds More Crossings

Projects around Jackson help animals maintain migration routes—and keep outdoor recreation safe for people

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To Keep Wildlife Off Roads and Trails, Wyoming Builds More Crossings
A moose walks across a street with car approaching from behind.
A moose crosses Route 390 near Wilson, Wyoming—a common occurrence in the area, where collisions with vehicles kill several moose every year. Four planned wildlife crossings around Wilson should help improve safety for humans and animals.
C. Adams National Park Service

In much of the rural West, states are building wildlife crossings—over- and underpasses to keep animals off roads and reduce wildlife-vehicle collisions. But in more populous areas, there’s another factor to consider: how to minimize encounters between wild animals and an increasing number of hikers and cyclists.   

Near the busy resort town of Jackson, Wyoming, where outdoor recreation drives the regional economy, two new projects will provide a dozen structures for furred, finned, and hooved creatures to safely pass under busy highways. What makes these projects different from most wildlife crossing projects is the presence of the existing human recreational paths to the Snake River, so both include modifications to those hiking and biking trails, incorporating novel features that steer animals away from sections where they might encounter people.

In the town of Wilson, just west of Jackson, tourists and commuters traveling along routes 22 and 390 converge at a busy T-intersection. Traffic on these roads is often over capacity, and incidents such as wildlife-vehicle collisions can create hours of delays for motorists. The Wyoming Department of Transportation (WyDOT) is preparing to upgrade the often-congested intersection and replace the aging bridge across the Snake River between Jackson and Wilson. 

The area provides important habitat for moose and elk—two species that help support the region’s thriving nature-based economy—and collisions with vehicles kill three or four moose a year here, enough for biologists to worry about a potential threat to the local population. The state Game and Fish Department is collaring moose to learn more about their activity in the area; WyDOT paid for 10 of the 30 collars for the study.

Thanks to a special excise tax approved by Teton County voters in 2019, the county has money to invest in wildlife features and is spending up to $3 million for two of three underpasses for moose and other big animals that WyDOT is building at the intersection. Additionally, the new bridge will extend farther than the old one, allowing wildlife to pass beneath it where they haven’t been able to do so.

Teton County engineer Amy Ramage says the project will address the complex interactions between wildlife, especially moose, and the many people who hike, bike, or run, going to and from boat ramps and a separate pedestrian bridge across the Snake. To minimize wildlife-human encounters, the project involves strategies such as gates in newly installed wildlife fencing so people can get to trails but animals can’t.

Construction on the Wilson project is scheduled to begin in 2023.

Wildlife guard (cattle guard) for  bighorn sheep
To reduce wildlife-human conflict, the Wilson project will include fencing and experimental gates such as this one in Thompson Falls, Montana, which combines a gate and cattle guard.
Marcel Huijser

South of Jackson, WyDOT is rebuilding 7 miles of roads and bridges along the Snake River. This work, scheduled to finish this October, includes eight underpasses designed to accommodate mule deer, elk, moose, grizzly bears, mountain lions, and small mammals while keeping motorists and pedestrians safe.

To reduce wildlife-human encounters along one pedestrian underpass at Game Creek, WyDOT resident engineer Bob Hammond designed a tunnel with curved ends, because most ungulates won’t enter a tunnel if they can’t see through to the other side. That underpass opened last fall and, so far, is working as designed, Ramage says.

A concrete tunnel with lights along the left hand side.
This pedestrian tunnel under U.S. Highway 89/189/191 south of Jackson is intentionally curved to minimize wildlife-human encounters. Ungulates such as elk and deer typically won’t enter a passage unless they can see through to the other side.
Wyoming Department of Transportation

Another crossing, intended to help a renowned mule deer herd maintain its 150-mile seasonal migration between the Red Desert and the Hoback Rim in Wyoming, is in a landslide zone, so designers opted for a box culvert—a square concrete tunnel that could be constructed without further destabilizing the local geology.

Three elk walking out of a tunnel into a snowy pasture.
Elk cross under U.S. Highway 89/189/191 at Flat Creek, where a bridge was lengthened to create room for animals to pass beneath it.
Wyoming Department of Transportation

Other crossings involved extending road bridges or leveling riverbanks to make it easier for animals to walk along the edge of the Snake River under the road. Lots of fencing and many cattle guards will also help keep wildlife and livestock out of traffic.

The complexity of the project pushed the price tag for the Jackson South project to approximately $130 million, with about $13 million going toward crossings, cattle guards, fencing, and other wildlife features. The Snake River bridge project near Wilson is expected to cost approximately $24 million. If everything goes as planned for people and wildlife, both projects will be worth every penny.

Matt Skroch is a project director and Leslie Duncan is a senior officer with The Pew Charitable Trusts’ U.S. public lands and rivers conservation project.