Frequent travelers on Interstate 25 between Colorado Springs and Denver might have some questions about what appears to be an interchange with no connecting roads under construction just north of Monument.

An interchange of sorts, the Greenland Wildlife Overpass is not for cars or humans.

“Elk love big open structures,” said Chuck Attardo, I-25 South Corridor Environmental Manager for the Colorado Department of Transportation.

The Greenland overpass, when finished in December of this year, will be the biggest animal crossing over a roadway in the state and the only one on Colorado’s stretch of I-25. Herd animals like elk, deer and pronghorn are expected to use the 200 by 200-foot overpass to move freely between the east and west sides of I-25 in a section of the Front Range under a long-standing conservation easement.

The overpass will be the final piece in a plan to manage animal movement in the I-25 Gap project, which has largely completed its goal of adding lanes and safety measures to the roadway. The overpass splits the four-mile span between two underpasses already in place to allow animals an option to cross safely.

The underpasses, while successful for a wide range of animals, are not the ideal solution for species that avoid the underground structures on instinct. Those animals have been essentially cut off from habitat west of the interstate up to the border of the Pike National Forest.

Julia Kintsch, an ecologist who consults with CDOT, has been studying wildlife behavior around the underpasses since their construction. Using cameras, including a small animal “photo booth” in a brush mound, she determines which animals are taking the journey and which turn back.

“Are they crossing all the way through, are they hesitating, or are they repelled?” she said.

Elk have used the underpasses sporadically, but CDOT and researchers like Kintsch are hoping they will use the overpass to find their disconnected kin. Once built, the overpass will be the subject of a Denver Zoo study to compare changes in genetic diversity between east and west herds.

“We can have connectivity between populations on either side of the interstate that have been historically disconnected by the highway,” she said.

The even more skittish pronghorn has not been documented using the underpasses and are almost always unwilling to cross a large roadway like I-25. There are no documented pronghorn herds on the west side of the interstate where the new overpass is under construction, a situation Kintsch hopes will change.

“It’s opening up access to habitat they haven’t had for generations,” she said.

The estimated $15 million project has been years in the making. Attardo said that infrastructure solutions to animal versus vehicle collisions were not on the table when many of Colorado’s major roadways like I-25 were constructed. The confrontations have led to more than just the death of animals and vehicle damage — fatal crashes and hours-long backups can also result.

“In the spring and fall movement season, there’s more than one wildlife (and) vehicle collision per day. Or there was, previous to this,” said Attardo.

Wildlife overpasses are a relatively recent development in road infrastructure; used to famous effect in places like Banff in Canada, the western U.S. is slowly adding the features to roads with high wildlife conflict. The Greenland overpass is not the first in Colorado, but its scale is novel to the state according to CDOT.

“It’s a project of international interest,” said Attardo.

Getting to the construction phase took convincing on multiple fronts. The section of I-25 where the new overpass is under construction is also home to one of the state’s major land preservation efforts of the last 25 years. Each side is under conservation easements dating back to agreements solidified between Douglas County and private land owners.

Attardo said representatives of the Malone family, which owns property including one slope of the proposed overpass, were initially skeptical about the potential impacts to elk hunting should the project go ahead. Media magnate John Malone is the nation’s second-largest property owner, according to the The Land Report rankings.

The project also lost out on federal grant funding in 2020.

“We just didn’t have enough design. There were too many unanswered questions,” said Attardo.

Things turned around for the overpass in 2023 when stakeholder buy-in and a new federal infrastructure bill allowed the project to benefit from grant funding through the Wildlife Crossing Pilot Program. CDOT also reached out to landowners about the benefits of the project to animal genetic diversity and safety, according to Attardo.

“We said, “Well, Mr. Malone, your prized elk are getting smashed on I-25,” he said.

Laura Sanford, Executive Director of Douglas Land Conservancy, said the project was a complement to ongoing conservation efforts. She said the land trust would be looking out for research results on the efficacy of the overpass.

“It’s exactly what we as a land trust want to see with our land,” she said.

Rye Austin, executive director for the Malone Family Land Preservation Foundation, said the Malones were “willing partners” in the project. The foundation is tied to the Malone family but with different land management holdings.

“It’s really going to be a net positive for wildlife migration,” he said.

Austin weighed in on how the Greenland overpass might be affected by controversial plans to build a Buc-ee’s travel center less than five miles away at the County Line Road exit. A lawyer with the foundation spoke out against the development plans at a Palmer Lake Board of Trustees meeting last month.

Austin said the foundation believed the travel center chain, known for being super-sized compared to other gas stations, could disrupt wildlife usage of the overpass. The proposed location borders the southern start of conservation easements along the interstate.

“We did anticipate that it would be developed at some point. We anticipated lower intensity use,” he said.

A CDOT spokesperson said the department would not comment on the proposed Buc-ee’s.

Construction on the overpass will have some overnight traffic impacts. During two weeks in July, resident engineer Dave Herzog said major lane closures will occur so construction crews can lay girders for the bridge. The closure will at one point include just a single temporary lane diverted around the interstate.

Another period of major closures is expected in August or September to pour the bridge deck, he said. The project’s estimated completion date is in December.