Travel in southern Castle Rock, Colorado, changed this week. The Town of Castle Rock announced on November 12, 2026, that the Crystal Valley Parkway and Interstate 25 interchange is fully open, nearly eight months ahead of schedule, after the southbound I-25 on- and off-ramps opened and connected to the new Crystal Valley Parkway bridge. The town called it the project's final major milestone, its No. 1 transportation priority, and the largest project of its kind in the town's history.
Source: Town of Castle Rock, Nov 12, 2026
The interchange sits at Exit 179 on I-25, the main north-south interstate between Denver and Colorado Springs. It was planned since the 1980s and designed to improve safety and mobility and to provide a key regional connection between I-25, southern Castle Rock and Douglas County, the town said. Construction began in 2024, and what was a nearly three-year project finished well ahead of its original schedule.
How the interchange was built, phase by phase
The opening came in stages. A new roundabout at Crystal Valley Parkway and East Frontage Road and the relocation of East Frontage Road were completed in January 2025. The new Crystal Valley Parkway bridge, built over the BNSF Railway tracks and I-25 with foundations on either side of and in the median of the interstate, was completed in November 2025, along with Dawson Trails Boulevard and Crystal Valley Parkway improvements west of the interstate. The bridge opened to east-west traffic in November 2025, which allowed the permanent closure of the West Frontage Road and its replacement with the new Dawson Trails Boulevard.
The northbound ramps, built east of I-25, were completed in July 2026, and the northbound I-25 on- and off-ramps opened that month, providing the first direct northbound I-25 access to this part of southern Castle Rock. The southbound ramps were built west of I-25 along the former West Frontage Road alignment, connecting to the Crystal Valley Parkway bridge through a new signalized intersection, and were completed in November 2026 — the piece that made the interchange fully open.
Who paid for it
The entire approximately $144.7 million project was completed within budget, including design, right-of-way acquisition and construction, the town said. The funding came from $53.6 million in developer contributions; $24 million from Douglas County for the interchange, plus $11 million for the West Frontage Road, which is now named Dawson Trails Boulevard; an $8.9 million grant from the Denver Regional Council of Governments; a $5.4 million BUILD grant from the United States Department of Transportation; $1.7 million in Town electric credits; and $900,000 from BNSF Railway.
The project was a collaborative effort among the Town of Castle Rock, Douglas County, the Colorado Department of Transportation and surrounding developers. The partners selected Jacobs Engineering to design the interchange and Kraemer North America to lead construction. The town said early collaboration and an innovative construction manager / general contractor delivery method, combined with a mild 2025 to 2026 winter, allowed crews to accelerate key work and deliver ahead of schedule.
Southern Castle Rock and the Crystal Valley and Dawson Trails communities grew for years without a direct I-25 interchange of their own. Douglas County's population grew almost 24 percent over the last decade, and the Crystal Valley Commons retail complex was built more than six years ago. The new Exit 179 gives those neighbourhoods, commuters and retail traffic direct access in both directions for the first time.
What it means for I-25 drivers and truckers
I-25 through Douglas County is one of Colorado's busiest commuter and freight corridors, carrying traffic between the Denver metro area and Colorado Springs and, for long-haul trucks, onward to the south. A full interchange at Crystal Valley Parkway spreads local trips that previously had to use neighbouring exits and frontage roads, and the project also includes a new bridge over I-25 and the BNSF Railway tracks, a roundabout, improved roadway connections and updated pedestrian and trail facilities, the town said.
Source: We Are Main Street, Nov 14, 2026
For residents of southern Castle Rock, the change is immediate: southbound drivers now have the on- and off-ramps that opened this month, matching the northbound access that opened in July, so trips to and from I-25 no longer require the detours that defined this part of town for decades.
What happens next
The driving work is done, but the project is not entirely finished. Landscaping and other finishing work will continue outside the roadway through early 2027, the town said. Drivers should still expect occasional finishing work near the interchange, even though all ramps are open. The town's announcement, with its project history and funding breakdown, is posted on its official website, CRgov.com.