Project Starts April 2026 – ROAD CLOSURE Necessary
This project is anticipated to start Monday, April 20, 2026. Construction will take place in two phases to minimize the duration of a full roadway closure of 120th Street that will be needed to complete the work.
- Phase 1 – Overlook Drive to southern entrance to Rock Creek Circle – April 20 to end of May
- 120th will remain open but the road will be narrowed and speeds will be reduced
- Phase 2 – Southern entrance to Rock Creek Circle to Dillon Road – End of May through December
- FULL CLOSURE OF 120th Street from S. Rock Creek Circle to Dillon Road
- Closure in place for cars, bikes, pedestrians
During the full closure, access to the Vista Business Park, Rock Creek Court, Commerce Court, and Rock Creek Circle will be maintained from the north.
The road closure is necessary due to the significant amount of earthwork that needs to be completed to construct the new road.
Background
Boulder County, in partnership with the City of Lafayette, is planning to reconstruct 120th Street between Overlook Drive in the City of Lafayette and Dillon Road in the City and County of Broomfield. Construction will widen the road to accommodate two five-foot paved shoulders with two-foot painted buffers to separate out shoulder users from vehicular traffic. The project will also flatten some of the extreme grades of the area’s hillsides to reduce energy use by the numerous large trucks and other vehicles that are currently using the road which will help reduce noise and fuel consumption.
Critical Project Issues and Needs
- Reconstruct 1.25 miles of 120th Street with new profile and pavement to improve drainage and reduce steep grades
- Widen pavement to 36-feet to allow for a vehicle lane in both directions along with two seven-foot buffered shoulders
- Add a northbound left-turn lane to the northern Rock Creek Circle intersection to improve safety
- Match the road width and striping of the 2021 City and County of Broomfield improvements at the Dillon Road intersection.
Design Exhibits
- Project Design Exhibits
- Roadway typical section shown below:
Public Meetings
- Previous Public Meetings
- Virtual Public Meeting – Aug. 24, 2021
- View the Aug. 24, 2021 public meeting (PASSCODE = +w3e&v^M)
Project Timeline
- Design – 2021 (COMPLETE)
- Construction anticipated to begin in April 2026
- Construction ends in December
Project Contact
- Andrew Barth, Public Works Communications Manager – abarth@bouldercounty.gov or 303-441-1032
Existing Conditions
Project Area Map
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