Castle Rock opens first northbound I-25 ramp at Crystal Valley

Drivers heading out of south Castle Rock now have a new way onto Interstate 25 as the first northbound ramp at the Crystal Valley interchange opens at the Crystal Valley Parkway and East Frontage Road roundabout. The move gives commuters, school traffic and neighborhood trips in the town’s growing southern edge another route north while easing pressure on local streets that have carried construction detours for months.

The opening marks a visible step in a project Castle Rock says has been planned since the 1980s and remains one of its top transportation priorities for safety, mobility and regional access in Douglas County. The Town of Castle Rock, Douglas County and the Colorado Department of Transportation are partners in the work, which is designed to link I-25 more directly to southern Castle Rock and eventually help relieve congestion at the Plum Creek Parkway interchange.

This ramp is only one piece of a much larger interchange buildout. Drivers still must travel through the roundabout and follow the westbound connection on Crystal Valley Parkway to reach the new northbound on-ramp, and the broader project will not be fully complete until 2027. In its April 16, 2026 project FAQ, Castle Rock said construction on the east side of I-25 was substantially complete, the new Crystal Valley Parkway bridge was already open to east-west traffic, and the northbound on- and off-ramps were expected to open in 2026.

Two more east-side ramps, including the northbound off-ramp and the northbound on-ramp from eastbound Crystal Valley Parkway, are expected later this summer. West of I-25, crews are still building the future elevated southbound on- and off-ramps and a new signalized intersection. Castle Rock says the project also includes a new bridge over I-25, reconstruction of frontage roads and new local road connections on both sides of the interstate.

The relocated West Frontage Road, now Dawson Trails Boulevard, is part of that work. Douglas County said construction on the roadway began Sept. 9, 2024 and was anticipated to be completed in fall 2025. Castle Rock says the road west of I-25 will eventually carry two through lanes in each direction once the full interchange is finished, and earlier project updates tied the east-side roundabout and frontage-road work to access for the emerging Dawson Trails area, including Twin Oaks, Yucca Hills and the future Dawson Trails development.

Even with the new ramp open, drivers should expect intermittent nighttime lane closures on I-25 through the summer, along with heavy trucks, machinery and flagging operations near the work zone. Castle Rock says the project will keep changing how traffic moves around Crystal Valley before it finally delivers the larger mobility shift that southern Castle Rock has waited decades to see.