Construction is about halfway done on what Colorado officials claim will be the world’s largest wildlife overpass – a 200-foot-wide, 209-foot-long structure spanning six lanes of Interstate 25 south of Denver.
Construction began in January on the I-25 Greenland wildlife overpass near the Greenland Interchange between the towns of Larkspur and Monument.
The project is on track to be completed in December, according to the Colorado Department of Transportation (CDOT).
“This overpass will be the world's largest structure over a major roadway for wildlife to cross,” according to CDOT.
The wildlife overpass will connect 39,000 acres of wildlife habitat on both sides of I-25.
The project comes with a $15 million price tag, according to CDOT.
By way of comparison, a pending project involving three wildlife underpasses and an overpass along a 25-mile stretch of Highway 26/287 near Dubois carries an estimated price of $28 million.
That project is meant to save hundreds of mule deer killed every year crossing the highway there. It’s hoped construction can begin by 2027, but that project faces a budget shortfall of about $16 million.
Colorado is about halfway through building what officials are touting as the world’s largest wildlife overpass – a $15 million megastructure spanning six lanes of Interstate 25 south of Denver. (Colorado Department of Transportation) 
Colorado is about halfway through building what officials are touting as the world’s largest wildlife overpass – a $15 million megastructure spanning six lanes of Interstate 25 south of Denver. (Colorado Department of Transportation) 
Colorado is about halfway through building what officials are touting as the world’s largest wildlife overpass – a $15 million megastructure spanning six lanes of Interstate 25 south of Denver. (Colorado Department of Transportation)
Closing The Gap
The Greenland Wildlife Overpass will seal a roughly 4-mile gap in wildlife crossings along I-25 between the Colorado towns of Castle Rock and Monument.
In that area, the highway cuts through a vital migration corridor for elk between summer and winter range, said Kara Van Hoose, the Northeast Region spokeswoman for Colorado Parks and Wildlife (CPW).
Along that gap, elk — as well as mule deer and pronghorn — have no good option for crossing I-25, she told Cowboy State Daily.
“There are always kind of serious crashes there,” because of collisions with wildlife, Van Hoose said.
During the spring and fall migration seasons, there is at least one wildlife collision per day there, according to CDOT.
Overpass Is A Better Option
Once completed, the overpass will be covered with soil and native plants, and wildlife fencing will funnel animals toward it.
Other parts of the wildlife crossing system in the area include underpasses.
However, CDOT, CPW and others involved in the project decided that a mega-sized overpass would be the best finishing touch to close the wildlife crossing gap, Van Hoose said.
“Underpasses can be narrow, and sometimes, there’s not that clear line of sight that animals need to have,” she said.
“Underpasses are primarily used by small game and nongame animals,” she added.
The overpass will feature gentle inclines, enticing big game animals to step onto it.
The greater visibility offered by the wide structure should make animals feel more comfortable, Van Hoose said.
CPW provided data about elk herd movements to help select the ideal location for the overpass, she said.
And it should have plenty of use. Colorado has more elk than any other state – with that state’s total elk population estimated at roughly 300,000.
Mark Heinz can be reached at mark@cowboystatedaily.com.
