CDOT Announces Next Steps for I-25 South Gap Project

June 29, 2018 -

DENVER—Today, CDOT and the Federal Highway Administration (FHWA) signed the official Finding of No Significant Impact (FONSI) report on the I-25 South Gap project. The finding—issued when environmental analysis and interagency review during the environmental assessment process conclude a project will have no significant impacts on the quality of the environment—allows CDOT to move forward with a project that will significantly improve the 18-mile section of I-25 between Monument and Castle Rock.

"Signing the FONSI is significant," said CDOT Executive Director Michael Lewis. "This is a necessary step before we can break ground on one of the most critical transportation projects in the state. The improvements will transform an aging section of a heavily traveled highway to one with greater capacity, new bridges and wildlife crossings. This will greatly improve safety, mobility and travel reliability."

For more than a year, CDOT undertook a planning and environmental linkages (PEL) study to identify a long-term vision for the 34-mile stretch of I-25 from Monument to C-470. As a result of the initial findings from the study and public input, CDOT identified the gap as the most urgent priority.

In fall 2017, CDOT and the FHWA launched an environmental assessment, which is an extensive process involving public participation to determine a preferred alternative that best meets the project's purpose and need. The environmental assessment was released in late May, followed by a month-long comment period. The comments are documented in the FONSI, which is the last step in the environmental approval process.

"Throughout the study phases and approval process for this project, we have engaged in one of the most significant public outreach efforts I have ever seen—listening sessions, community meetings, online feedback, and more," continued Lewis. "We're grateful to the many citizens who participated in the process, offered input, and provided constructive criticism."

Funding has been identified, and construction is scheduled to begin later this summer.

Key features of the project:

  • Widen by one lane in each direction of the 18-mile stretch of I-25 between Monument and Castle Rock.
    • The new lane in each direction will operate as an Express Lane. Motorists will always have the choice of taking the two general-purpose lanes for free, or they will be able to take the Express Lane for a reliable trip in exchange for a variable toll.
    • The Express Lane will provide a level of long-term travel reliability that a new general purpose lane can't.
  • Widen shoulders to allow room for enforcement zones, maintenance and detours around incidents.
  • Rehabilitate structures and pavement, including the replacement of four bridges.
  • Build four wildlife underpasses and expand the existing one at Plum Creek.
  • Improve lighting, signage, fencing and other features.

The project will cost an estimated $350 million.

I-25 South Climbing Lane

CDOT is likely to move forward with the construction of a one-mile long truck climbing lane or passing lane on southbound I-25 to improve travel on the climb to Monument Hill. This section of southbound I-25 would have an Express Lane, two general-purpose lanes and a truck climbing lane. This section of I-25 has the steepest elevation, and a climbing lane would help to move freight more efficiently.

The truck climbing lane meets an engineering need and addresses one concerns received during the environmental assessment process.

This work, which is not within the scope of the environmental assessment, would require an environmental review. CDOT anticipates the construction of the climbing lane would start in early 2019, and would be part of the overall improvements to the gap. Once construction is completed, the new climbing lane would likely be in place.