A wildlife crossing system spanning Interstate 25 near Larkspur, Colorado, has delivered a 91% reduction in wildlife-vehicle collisions during its first 10 months, slightly exceeding transportation officials’ projection of 90%. Opened in December, its centerpiece is North America’s largest wildlife overpass: a structure measuring 200 feet wide and 209 feet long, with an area of 41,800 square feet. The bridge carries animals over six lanes of highway.
The broader infrastructure includes five underpass tunnels, offering alternative routes for smaller or more hesitant animals, while extensive fencing channels wildlife toward the crossings. Bears, elk, moose, rabbits, and northern leopard frogs are among the animals benefiting from safer passage. A pronghorn filmed using the overpass marked the first recorded crossing in 30 years, after decades in which the highway obstructed the species’ migration. The benefits extend to motorists: the Larkspur–Monument corridor previously averaged one wildlife-vehicle collision per day. With fewer crashes requiring lane closures, traffic delays have declined by 9%.
Colorado is now evaluating six additional locations for wildlife overpasses, including its first crossing designed specifically for Rocky Mountain bighorn sheep. Proposed sites include westbound Interstate 70 at East Vail Pass between Vail and Copper Mountain, Interstate 25 north of the New Mexico border, and US 160 east of Cortez. Other locations under consideration are Colorado 40 west of Craig and an area near US 287 south of the Wyoming border. These plans would extend the use of dedicated crossings to additional Colorado roads.
