120th Street Reconstruction

120th Street Shoulders Project - Overlook Drive to Dillon Road

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 (see project area map). The proposed design widens 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.

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

120th Street shoulders project roadway typical sectionPublic Meetings – Public Input

There are currently no public meetings scheduled.

  • Previous Public Meetings

Project Timeline

  • Design – 2021 (COMPLETE)
  • Construction anticipated to begin in 2025
    • 120th will need to be closed between Overlook Drive and Dillon Road in order to complete this major undertaking. Businesses located within the closure zone will be allowed to exit, but must travel north. Entrances will be maintained from the southbound direction.

Project Contact

Existing Conditions

120th Street Reconstruction project - Existing conditions looking north

120th Street Reconstruction project - Existing conditions looking south

Project Area Map

120th Street Shoulders Project Area Map

Contact Us

Public Works Department (formerly Transportation)

Submit a request


2525 13th St.
Boulder, CO 80304

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Mailing Address

P.O. Box 471
Boulder, CO 80306