On the busy stretch of Interstate 25 between Denver and Colorado Springs, a new piece of infrastructure is quietly reshaping the daily movement of animals and drivers alike. The Colorado Department of Transportation (CDOT) completed a wildlife-only bridge in December 2025the largest of its kind currently in North Americato help species like elk, bears, coyotes, and pronghorn safely access 39,000 acres of habitat. Within its first nine months, wildlife-vehicle collisions along the corridor fell by 91 percent.
A bridge designed for animalsand safer roads
Spanning I-25s six lanes and entirely carpeted in grass, the overpass is engineered to read as uninterrupted habitat from an animals point of view. Before it opened, dozens of animals were killed by vehicles every year on this route, sometimes as many as one per day during migration seasons. By drawing wildlife up and over the traffic, the structure reduces risk for both migrating herds and the people behind the wheel, along with the costs that come with collisions.
The I-25 crossing is part of a growing network of wildlife passages under development across the U.S., including a handful more in Colorado that use underpasses and smaller bridges tailored to local terrain and species behavior. Together, these targeted links stitch fragmented habitat back into a functional whole.
Early outcomes and a telling image
The 91 percent reduction in crashes within nine months underscores the speed at which well-designed crossings can make a difference. The human response has been immediate, too. Brandon Marette, a wildlife biologist with Colorado Parks and Wildlife, told CBS News, One of the most heartwarming moments for me was when CDOT sent me a picture of an elk mama taking her calf under I-25.
From the grass-topped span to coordinated passages below, the shift is clear: infrastructure can be calibrated to the needs of wildlife without compromising mobility for people. Along Colorados most traveled north-south artery, the early dataand that quiet photographpoint to a future in which migration routes and highways no longer collide.
