Colorado wildlife overpass slashes vehicle collisions by 91 percent

Wildlife overpass delivers immediate safety gains

Ten months after opening, the wildlife overpass that spans Interstate 25 near Fort Collins has already lowered wildlife vehicle collisions by 91 percent, according to a report released by Colorado officials. The structure bridges a thirty nine thousand acre stretch of public and private land, giving animals a safe route over one of the state’s busiest highways. By diverting elk, bears, pronghorn and even northern leopard frogs away from traffic, the bridge saves lives and protects motorists from costly accidents.

How the overpass works

The overpass is a vegetated bridge that mimics natural habitat. It is wide enough for herds to move together, and its gentle slope encourages use without forcing animals to climb steep grades. Sensors installed at both ends record crossings, while motion‑activated cameras capture images that help researchers track usage patterns.

Key design features

Native grasses and shrubs provide cover and foraging opportunities.
Fencing along the highway directs animals toward the bridge.
Lighting is minimal to reduce disturbance to nocturnal species.
Drainage systems prevent water pooling that could deter crossing.

Species taking advantage of the crossing

Since its completion, a surprising variety of wildlife has been documented on the overpass. The most frequent users are elk and black bears, but the structure also supports smaller and more vulnerable species.

Large mammals

Elk – families and solitary males have been seen moving in both directions.
Black bears – individuals use the bridge during foraging trips.
Pronghorn – the fast‑moving antelope takes advantage of the open corridor.

Amphibians and reptiles

Northern leopard frogs – breeding groups cross during wet seasons.
Western rattlesnakes – occasional sightings have been recorded.

Impact on driver safety

Before the overpass opened, the I 25 corridor recorded an average of 12 wildlife related crashes per month. After the bridge became operational, that figure fell to just one incident per month, representing a 91 percent reduction. The decline translates into fewer injuries, lower insurance costs and less road closure time.

Economic benefits

Reduced vehicle repair costs – the state estimates savings of over two million dollars annually.
Lower emergency response expenses – fewer crash scenes mean less demand on police and fire services.
Improved traffic flow – fewer accidents keep commuters moving during peak hours.

Expert perspective

"One of the most heartwarming moments for me was when Colorado Department of Transportation sent me a picture of an elk mother taking her calf under Interstate 25," said Brandon Marette, a wildlife biologist with Colorado Parks and Wildlife. "All came to fruition in that one moment. That elk with her calf was just standing there in safety."

Broader environmental significance

Habitat fragmentation is a leading cause of wildlife mortality worldwide. By reconnecting fragmented ecosystems, structures like this overpass help maintain genetic diversity and support species that require large ranges. The Colorado project aligns with national goals set by the Federal Highway Administration to integrate wildlife considerations into transportation planning.

Research published in a peer‑reviewed study on wildlife crossings highlights that overpasses can reduce animal mortality by up to 85 percent when combined with proper fencing. The Colorado experience exceeds that benchmark, suggesting that careful site selection and community involvement play critical roles.

Future plans and replication

Colorado officials are already evaluating additional crossing sites along other interstate segments. The success of the I 25 overpass is being used as a model for projects in Utah, Wyoming and Montana, where similar habitat corridors have been identified.

Funding for future structures is expected to come from a mix of state transportation budgets, federal grants and private conservation organizations. The collaborative approach demonstrates that wildlife protection and infrastructure development can coexist without compromising either goal.

Public response and education

Local communities have embraced the overpass as a symbol of stewardship. Schools near the bridge have incorporated field trips that teach students about ecosystem connectivity, while signage along the highway informs drivers about the importance of the crossing.

Travelers who spot wildlife on the bridge often share photos on social media, raising awareness and encouraging support for similar projects nationwide.

As the overpass continues to serve both animals and motorists, it stands as a tangible example of how engineering solutions can mitigate human impact on the natural world.