‘World’s Largest’ Wildlife Bridge Reaches a Construction Milestone

What is being billed as the “biggest wildlife crossing ever” over a major roadway, as envisioned by Colorado’s Department of Transportation, the Greenland Wildlife Overpass Project has recently reached a construction milestone: The project’s halfway mark.

The Denver Gazette details that the massive wildlife overpass under construction on Interstate 25 between Larkspur and Monument, is designed to protect local drivers and wildlife in an area seeing an average of one animal-vehicle crash per day in the spring and fall. It is being saluted for simultaneously tackling public safety and conservation.

It will serve as the world’s largest bridge structure for wildlife, and will cover nearly an acre when completed at the end of 2025, connecting 39,000 acres of habitat within the Douglas Country Land Conservancy to more than one million acres of the Pike National Forest.

Measuring 200 feet (62 meters) wide and 209 feet (64 meters) long when ready, it will span six lanes of traffic on a stretch of the interstate travelled by over 100,000 vehicles daily.

“Colorado is leading the nation in protecting our treasured wildlife by building the world’s largest safe passage for animals like elk and moose,” said Douglas County Senator, Michael Bennet. “This Bipartisan Infrastructure Law investment will lead to a 90% reduction in wildlife fatalities and make this busy stretch of I-25 safer for drivers and animals alike,” he added, as quoted in a July 2025 news release from Colorado’s Department of Transportation.

Herds Over Highways
Wildlife crossings, also known as wildlife bridges or wildlife corridors, are overpass structures designed to help animals safely cross busy roads, reducing wildlife-vehicle collisions significantly

A key advantage, as Environment America details, is their ability to reduce habitat fragmentation. Wildlife crossings, of which there are 1000 in the US alone, help reconnect habitats that become fragmented as humans build roads, cities, dams and other infrastructures. This human activity ends up carving up populations of animals, which become fragmented and isolated, with animals denied the ability to move as needed to find food and shelter, as well as mate. This leads them to attempt to cross hazardous, major roads, and leads to wildlife-vehicle collisions that can be fatal for humans and animals.

These bridges are typically covered with native greenery so that they blend into the landscape while strategic fencing guides animals towards the crossing.

Another noted advantage is that wildlife corridors can help reduce animal population decline, and maintain genetic diversity within assorted animal populations, with an increased gene flow noted.

Studies that measure the effectiveness of wildlife bridges are encouraging. According to an ARC Solutions publication, “Wildlife Crossing Success Stories in the Western States,”  when located in areas of known wildlife movement, wildlife crossings with elements such as fencing have reduced wildlife-vehicle collisions by up to 97 percent.

Which Animals is Colorado’s Wildlife Bridge Designed to Help?
While five nearby wildlife bridges are already in existence, the new Greenland Overpass is aimed specifically at giving elk (more live in Colorado than in any other US state) and other larger animals a safe way to cross a busy freeway.

As Smithsonian Magazine explains, twice a year, thousands of elk, mule deer and pronghorn (antelopes that are smaller than deer) migrate between their seasonal ranges in the state. They spend their winters grazing at lower elevations, and their summers in the mountains.

Kara Van Hoose, the Northeast Region spokeswoman for Colorado Parks and Wildlife outlines to Cowboy State Daily, that “the greater visibility offered by the wide structure should make animals feel more comfortable,” as will the gentle inclines.

Environment America also draws attention to the need to plan wildlife bridges so that they are in sync with the needs of particular species to work as intended. It outlines how  bigger mammals such as deer, wolves, and grizzly bears prefer a wide, high and short crossing, while species like cougars and black bears like long and narrow underpasses.

Moose, bears, mountain lions, and other smaller animals are also expected to use the structure.

Experts also emphasize that animals need time to get used to wildlife overpasses and start using a new bridge. There can be a learning curve of up to five years among wolves and grizzly bears, for instance.

In the next phase of the $15 million Greenland Wildlife Overpass Project, a bridge superstructure will be constructed over the girders. This work will include pouring the concrete bridge deck,  adding sloped entrances, preparing the soil and wildlife landscaping using native grasses, and installing wildlife fencing, according to the 2025 Colorado Department of Transportation media release.