Flagstaff Road Reconstruction

New Information:


During the 2013 flood event, Flagstaff Road was badly damaged. The most extensive damage occurred approximately 1,000 feet up from Gregory Lane, where a major slope failure washed away a 200-foot section of the roadway going up Flagstaff Road.

Flagstaff Road washout area

Temporary measures were put in place following the flood, which provided one-lane, traffic signaled-access to residents and visitors. Permanent repairs are necessary to ensure long-term safety for all users of Flagstaff Road. 


  • A contractor will construct a 200-foot long bridge in the uphill lane that spans the washed out area and more. 
    • The picture to the right is of the drill rig that's currently drilling holes for the caissons that the bridge supports will sit on/in. 
Flagstaff Drill Rig


  • Work began on June 23, 2014 and will last through November 2014 - Weather Permitting

Traffic Impacts:

  • Because the section of roadway where construction will take place is narrow (12-feet wide), Flagstaff Road will need to be closed in both directions from 8:30 a.m. to 3:30 p.m., for the duration of the project.
    • Closed at Baseline Road and 6th Street on the east side
    • Closed at Panorama Point on Flagstaff Road on the west side
  • Flagstaff Road will reopen to motor vehicle and bicycle traffic at 3:30 p.m., Monday through Friday, and will remain open all day on weekends.
    • No pedestrians are allowed to walk through the zone at any time due to the narrowness of the open lane
  • Access to Flagstaff Road above the closure will be available from Gross Dam Road off of Highway 72.
  • Gregory Canyon Road will be closed to visitors 
  • The traffic-signal through the closure area is currently set for 3 minutes 10 seconds. The timing was set this way after a traffic engineer monitored the site and found that this was the longest time it took a cyclist to move through and clear the work zone. 
    • The time was also increased when the project started because the work zone was increased from 300 to 900 feet, which means it takes longer for bikes to move through the closed area. 
Flagstaff Road girder install September 2014

Access to Flagstaff Road During Work Hours:

  • Hiking trails on Flagstaff will remain open and accessible during work hours. You must carry your bike down hiking trails - no riding
  • Chapman Drive is open bikers, but you have to take Chapman Drive back down if you want to get back to Boulder prior to 3:30, Monday through Friday. 
  • Gross Dam Road from Coal Creek Canyon Drive/Hwy 72 can be used to access the top of Flagstaff Road

Emergency Services Access:

Arrangements have been made with the Boulder County Sheriff's Office, Rocky Mountain Fire District, and Boulder Police to ensure that emergency responders can respond to any situation both above and below the closure. Emergency crews will be staged above the closure to help shorten response time.

Project Contacts:

Dan DeLange  
Boulder County Transportation

Andrew Barth  (Send Andrew an email if you'd like to join the project email list and receive timely project updates)
Boulder County Transportation - Communications

Contractor = Structures Inc. - 720-244-9150