Douglas County will close two County Line Road intersections in Highlands Ranch one at a time starting Monday, Nov. 9, 2026, as crews continue work on the $30 million County Line Road widening project.
The closure schedule
The two closures happen back to back, not at the same time:
- E. Phillips Avenue at County Line Road: full closure starting as early as 7 a.m. Monday, Nov. 9, for about one week, to install underground storm sewer pipe. During this closure, County Line Road at Clarkson Street is reduced to one lane of alternating traffic, controlled by flaggers.
- Clarkson Street at County Line Road: full closure starting as early as 7 a.m. Monday, Nov. 16, for about one week, immediately after Phillips Avenue reopens, to complete reconstruction of the existing roadway.
The county says crews won't work around the clock. The roadway can't reopen outside work hours because of significant earthwork and the inability to safely support traffic until each phase is complete.
Detours
Commuters (through traffic) are detoured via S. Broadway, E. Mineral Avenue, E. Dry Creek Road, University Boulevard and Dad Clark Drive.
Residents can still reach Phillips Avenue via E. Mineral Avenue, and Clarkson Street via E. Dry Creek Road, University Boulevard and E. Mineral Avenue. Business access remains open throughout.
The bigger project
These closures are part of the County Line Road Widening and Reconstruction project, between University Boulevard and Broadway. Douglas County is running it with the City of Littleton, the City of Centennial and the Denver Regional Council of Governments. Construction began in September 2025, the project costs $30 million, and it's slated to finish in September 2027. When complete, the county says the project will add one travel lane in each direction, a new traffic signal at Clarkson Street and County Line Road, a mill-and-overlay in Littleton between Phillips Avenue and Broadway, and new sidewalks.
For project updates, sign up for email alerts at the county's County Line Road Widening and Reconstruction project page and select "Road Work/Cone Zone," or call the project hotline at 720-795-9622, ext. 2523.
Other work on this corridor
County Line Road has seen other recent closures; see our earlier coverage of the March 2026 utility closure between Yosemite and Quebec. For more Highlands Ranch happenings, see our Highlands Ranch events coverage.
Sources: Douglas County, "Upcoming closures of County Line Road intersections in Highlands Ranch starting Nov. 9", posted Nov. 6, 2026, checked Nov. 7, 2026.