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 the 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 project is expected to cost about $75 million to complete. The Town received a $5.2 million BUILD grant from the U.S. Department of Transportation. The Town is committed to setting aside $20 million in resources for the project and other funding sources are being determined.

Designing and constructing the interchange will be a multi-phased collaboration among the Town of Castle Rock, Douglas County, Colorado Department of Transportation and the local development community. 

The interchange includes construction of a bridge over I-25, north and southbound on-and off-ramps, a bridge over the BNSF railroad tracks and relocation of segments of the east and west frontage roads.

Purpose and need for the project

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

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

What is happening now?

We are working with an engineering firm to refine the preferred alternative selected in the Finding of No Significant Impacts. Next, will contract with a construction company for insights into constructability and project costs.

Schedule CVI Schedule 0921

Proposed 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 Railroad 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.

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Map of proposed Crystal Valley Interchange overview.