wildlife crossing

An artist’s rendering of the completed wildlife overpass on US 160, east of Durango. (Image courtesy of CDOT)

A critical migratory pathway for mule deer and elk in southwestern Colorado, which has been under construction since earlier this year, is about to receive its crowning glory: a highway overpass.

Overpasses are considered the gold standard for wildlife crossings, because so many different animals — including the wary, and the top-heavy (such as bull elk, with their towering antlers) — will readily use them. The catch is that overpasses are not only expensive, they must be placed just so. Not every stretch of highway can accommodate them. Two miles of U.S. Highway 160, east of Durango near Chimney Rock National Monument, includes such a stretch. Even so, much work has already been done to help accommodate it. The first phase of excavation, which has been taking place since this spring, has involved widening and extending a couple of lanes at the intersection of Highway 151 and 160. The really heavy lifting begins next week, and will require the full highway’s closure as a pair of pre-cast concrete forms are dangled above the roadway. The work will be done overnight (a suggested detour goes south through Farmington, New Mexico), Monday through Friday, Sept. 20-24, between 9 a.m. and 6 p.m. The crossing is the result of a collaboration between “federal and state agencies, academics, nonprofits, biologists and engineers,” according to a news release, who formed the Colorado Wildlife and Transportation Alliance (the group has also worked together on the new crossing to be installed near the Billy Creek Wildlife area, outside Ridgway).

The Southern Ute Tribe provided critical support to this project, by offering “data that identified seasonal migration patterns and habitat in the area.” The tribe has also offered $1.6 in financial support for the crossing; additional support came from Colorado Parks and Wildlife, the National Fish and Wildlife Foundation, the Mule Deer Foundation, and the Rocky Mountain Elk Foundation.

In addition to the overpass, a wildlife underpass is being added below the work area. A stretch of eight-foot-high — in other words, too high for deer to jump over — “exclusion” fencing will line this two-mile stretch of road. A large “deer guard” will be erected at the approach from 151 to the intersection with 160 to prevent mule deer — the native deer to western Colorado, named for their large, mule-like ears — from hopping into busy traffic. So-called escape ramps (essentially, small, earthen hills) will be added inside the roadway, so animals that manage to breach the highway can safely exit to the other side of the fencing.

Keeping animals off increasingly busy stretches of road, yet allowing them to retain ancient migratory crossings (established many thousands of years before humans ever arrived in southwestern Colorado) is key to many species’ survival. For CDOT, there’s another imperative: preventing the human deaths that can come from cars colliding with wildlife. “Because this area an abundance of big game, wildlife-vehicle collisions make up more than 60 percent of the crashes at this location,” Julie Constan, CDOT’s southwest regional transportation director, has said. “This $11.3 million project is expected to reduce those collisions by at least 80 percent.”

Next up in southwestern Colorado will be a crossing project in another key spot — which will include an additional underpass, and other improvements. This one will take place on U.S. 550, at the Billy Creek Wildlife area between Ridgway and Montrose. On Wednesday, key representatives from CDOT, CPW and the BLM and others gathered to discuss the project, and survey the site. (The Pew Charitable Trust will contribute financial support, and paid for lunch.) The builders have high hopes for this project’s success, when it comes to saving human lives, and wildlife. “Conceivably, the whole corridor” between Ridgway and Montrose will be filled in with wildlife protection of one form or another sometime in the next five years, CDOT biologist Mark Lawler said. “We had animals moving through almost right away after we constructed the underpass” near Colona. In addition to preventing injuries to drivers and damage to vehicles, “We know the Billy Creek project will connect big chunks of habitat of public land, and important migration corridors.” The crossing chiefly aims to protect mule deer, large animals killed in especially large numbers on this stretch of roadway. Although an overpass is not being considered at this site, the underpass will be tall enough to accommodate elk: it will be 25-35 feet wide, Lawler estimated, and 13 feet high. “Elk use structures of this size, definitely,” he added. “We feel like we can get something in here” over the next couple of years “before traffic volumes increase and it becomes truly lethal for the animals, and they start looking elsewhere” to migrate, and, perhaps as a result, herd numbers diminish even further.

“Boom!” the biologist summed up of the Billy Creek project. “It’s on.”