Largest wildlife overpass in North America opens across six-lane interstate
The wildlife overpass in Douglas County, Colorado, spans Interstate 25 and connects 39,000 acres of habitat, allowing elk, deer, bears, mountain lions and other animals to cross safely.
A $23-million span that allows wildlife and people to cross over a parkway in San Antonio, Texas, is now open. Leaders say the investment is already paying off.
Colorado has opened the largest wildlife overpass in North America in an effort to reduce animal-related crashes by as much as 90% along a stretch of Interstate 25 in Douglas County.
The Greenland Wildlife Overpass connects 39,000 acres of habitat on both sides of the interstate, allowing elk, deer, bears, mountain lions and other animals to cross the six-lane highway safely. Colorado transportation officials said the overpass addresses a 3.7-mile gap in wildlife crossings. About 100,000 vehicles travel through the area each day.
According to the Colorado Department of Transportation, the Greenland crossing is part of a larger wildlife crossing system that includes underpasses and fencing throughout the Interstate 25 South Gap project. Prior to construction, the area averaged about one wildlife-vehicle crash per day during peak fall and spring migration seasons.
The nearly one-acre Greenland wildlife overpass in Douglas County, Colorado along I-25. (Image credit: CDOT)
“The I-25 Greenland wildlife overpass is critical to the safety of both wildlife and motorists,” CDOT Executive Director Shoshana Lew said in a statement. “The overpass is an essential component of the wildlife crossing system in this area, which is expected to reduce wildlife-vehicle crashes by 90%.”
Colorado officials said the overpass is the largest bridge structure built specifically for wildlife in North America, measuring 200 feet wide and 209 feet long and covering roughly one acre. Its construction required 76 girders to support the bridge deck.
The Greenland overpass was designed primarily with elk and pronghorn in mind, species that require wide, open spaces to cross safely.
How do animals know to use wildlife crossings?
The Arizona Game and Fish Department recently addressed this common question about a new wildlife crossing under construction on Interstate 17.
Similar to the crossing in Colorado, the I-17 crossing will include "exclusionary fencing."
"This is a strip of tall fencing that stops animals trying to cross the road and guides them to the overpass instead," the department said. "Data collection from similar projects here in Arizona has shown that once animals learn to use the wildlife crossing, they pass that knowledge down to the next generation."
Protecting wildlife on the move
Wildlife crossings have proven successful in other states, and more are opening each year.
According to the Arizona Game and Fish Department, a wildlife crossing on State Route 260 reduced elk collision by about 85-97% with more than 10,000 documented animal crossings. Another crossing on U.S. Highway 93, also in Arizona, hasn't seen a wildlife collision since 2014.
Crews placed the first layers of soil over the surface of the Wallis Annenberg Wildlife Crossing in Agoura Hills, California, on March 31.
Utah has built more than 50 wildlife crossings statewide, with the first opening in 1975 along Interstate 15.
In 2021, the Robert L.B. Tobin Land Bridge opened in San Antonio, Texas, spanning six lanes of traffic and measuring approximately 150 feet wide.
In California, a $92 million vegetated bridge is under construction across U.S. 101 to help mountain lions, bobcats, foxes and coyotes cross safely. The overpass is expected to be about 210 feet long and completed in 2026.
Report a Typo
