I-25 South "The Gap" Environmental Assessment: Monument to Castle Rock

The Issue

Over the last year, CDOT has undertaken a Planning and Environmental Linkages (PEL) study to identify a long-term vision for the 34-mile stretch of I-25 south from Monument to C-470. As a result of the study, CDOT has identified the 18-mile segment from Monument to Castle Rock—known as "the Gap"—as the most urgent and highest priority.

To address that priority, CDOT has started an environmental assessment (EA), with the goal of having this stretch of the highway ready for construction by November 2018.

The Project

The proposed action for the I-25 South Gap EA is to add one travel lane in each direction between Monument and Castle Rock. This action will address the existing bottleneck and balance lane capacity along the corridor.

The proposed action will also widen shoulders to improve safety and incident management, as well as address safety concerns related to wildlife crossings.

About the Gap

Monument circa 1955

I-25 south from C-470 to Monument—in particular, the 18-mile segment known as "the Gap"—has been a top concern for travelers, law enforcement, local officials and CDOT. Improving safety, travel times and reliability are at the top of the list of concerns to address.

As one of the major thoroughfares in Colorado, this segment of highway connects Colorado's two largest cities—Denver and Colorado Springs—and is projected to become increasingly traveled as the state's population grows. This largely undeveloped section of I-25 south has remained essentially unchanged since I-25 was originally built in the 1960s.

Today, the highway's northbound and southbound two-lane configuration, horizontal curves, vertical grades and narrow shoulders create limited options for drivers to maneuver slow-moving vehicles, crashes, or other obstacles—especially when traffic volumes are high. As a result, this corridor experiences regular congestion and traffic incidents, leading to serious breakdown and queuing. The problems are compounded because there are no alternative routes and the frontage road system is disconnected.

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