Crystal Valley Interchange

Construction of a new interchange at Interstate 25 and Crystal Valley Parkway is a top transportation priority for the Town. The project will improve safety and mobility in the surrounding community and provide a key regional transportation link from I-25 to southern Castle Rock and Douglas County.

The interchange includes construction of a bridge over I-25, north and southbound on- and off-ramps, a bridge over the BNSF Railway tracks, relocation of a segment of the East Frontage Road and a connection to the relocated West Frontage Road from Tomah Road to the new interchange as a separate project by the Town and Douglas County. 

Interchange structure

The Preferred Alternative of the Crystal Valley / I-25 Interchange Environmental Assessment includes a diamond interchange with Crystal Valley Parkway crossing over I-25 on the east, and Territorial Road on the west. Crystal Valley Parkway will be constructed with two lanes in each direction between the relocated east-and west-side frontage roads. 

Crystal Valley Parkway will cross over I-25 with a grade separation. The Parkway will be constructed to accommodate the current configuration of I-25 in each direction. The new interchange will also be wide enough to accommodate a proposed additional track by Burlington Northern Santa Fe Railroad.

The proposed new interchange requires the I-25 northbound on- and off-ramps to be located between northbound I-25 and East Plum Creek. This requires relocating a portion of the existing I-25 East Frontage Road, about one-half mile north and south of Crystal Valley Parkway. Additionally, the proposed I-25 southbound on- and off-ramps will be located between the BNSF Railway and the southbound I-25 lanes. This requires relocating a portion of the existing I-25 West Frontage Road between Yucca Hills Road to the north and Tomah Road on the south. Roadway approaches to the bridge over Plum Creek will be modified, the bridge will not be impacted by this construction.

Refinement to the preferred alternative will be focused on optimizing traffic operations and maximizing construction efficiency. Possible considerations include roundabouts and phasing of the construction to minimize traffic disruptions. Another project element that will be considered is multimodal additions such as sidewalks, recreation trails, bike lanes and a carpool lot.

At this time, the cost of constructing the interchange ranges from $75 to $80 million. The entire project cost, which includes design, right of way and construction is estimated at $120 million. The Town received a $5.4 million BUILD grant from the U.S. Department of Transportation and is committed to setting aside $20 million in resources for the project. Other funding sources are being determined from both public and private sectors. Refinements to the costs will be a result of the preliminary design and the addition of a contractor to the team.

Rendering of the future Crystal Valley interchange
Rendering of the Crystal Valley interchange once construction is complete.

Purpose and need for the project

This project will improve access and safety from the south end of Castle Rock south to the Tomah Road interchange. The purpose of the interchange includes:

  • Enhancing the local ancillary roadway network
  • Eliminating one railroad crossing, thereby improving safety of access

Project schedule

The schedule has been laid out to align stakeholder meetings and outreach with the design schedule. This project schedule is approximate and subject to change.

  • 2023: Complete final design
  • Early 2024: Begin construction
  • 2026: Construction complete

Project documents

Project updates

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