On the final 18-mile, four-lane stretch of I-25 between Denver and Colorado Springs, a $330-million project has added a tolled express lane in each direction, improved safety for the traveling public and added four wildlife underpasses, more than 28 miles of wildlife exclusion fence and widened shoulders. When funding was announced for this high priority corridor, the goal was to complete the project in five years.

An aggressive design and construction schedule began in 2018. While constructing the northernmost six miles of the project, design continued for the remaining 12 miles, resulting in three design and construction packages for the full corridor. Funding was later identified for the replacement of the County Line bridge and an added southbound truck climbing lane from Greenland to Monument, which became the fourth package. Despite the additional scope, the toll lane opened to the traveling public in December 2021, almost a year ahead of schedule, with the entire project reaching completion in November 2023. At its peak, all 18 miles of the corridor were under construction—the most miles constructed in one project in state history.