Colorado Overpass Cuts Wildlife-Vehicle Crashes by 91% in 10 Months

A wildlife overpass spanning Interstate 25 in Colorado has cut vehicle-animal collisions by 91% in its first 10 months of operation, according to a newly released report cited by The Guardian.

How much did collisions drop?

The Colorado Department of Transportation says the corridor averaged one wildlife-vehicle crash a day before the overpass was built, the Guardian reports. Since completion, that rate has fallen 91%, according to the report.

Where is the overpass and what does it connect?

The structure sits on Interstate 25 between Denver and Colorado Springs, two of the state's largest cities. It spans six lanes of traffic and links 39,000 acres of habitat on either side of the highway, the Guardian reports. The bridge is covered in grass, with sloped entrances designed to ease animal crossings.

What animals have used it?

State wildlife officials have tracked elk, bears, pronghorn and northern leopard frogs crossing the overpass since it opened, according to the Guardian's report. Brandon Marette, a wildlife biologist with Colorado Parks and Wildlife, described one moment to CBS News that officials flagged as significant.

"One of the most heartwarming moments for me was when [the Colorado Department of Transportation] sent me a picture of an elk mama taking her calf under [Interstate 25]," Marette told CBS News, as quoted by the Guardian. "All came to fruition in that one moment. That elk with her calf was just standing there in safety."

Why are states building these overpasses?

Wildlife-vehicle collisions can injure or kill both drivers and animals. Research cited by the Guardian has found that overpasses are effective at "nearly eliminating" these crashes in the corridors where they're built, and that the structures often "pay for themselves" by preventing costly collisions over time. This region of Colorado sees high volumes of large-game movement, state officials told the Guardian, which made it a priority site. Officials also noted that underpasses and tunnels frequently fail to work for big game, favoring an elevated crossing instead.

How many wildlife crossings exist nationwide?

Nearly 20 wildlife crossings are currently under construction across the United States, the Guardian reports. The Colorado overpass is described as the largest such structure built so far. The project reflects a broader shift among state transportation agencies toward engineered crossings as a tool for managing both traffic safety and habitat connectivity, rather than fencing or signage alone.

Colorado officials have not released a timeline for additional crossings in the state, according to the available reporting. The Department of Transportation and Colorado Parks and Wildlife continue to monitor the Interstate 25 site for further data on crossing patterns among elk, bear and other species documented since the bridge opened ten months ago.