CO 119 Boulder Canyon Improvements

Work this Week
August 17-24

Full Canyon Closures Monday through Thursday and 40-Minute Delays 
Monday, August 19 through Friday, August 23, Colorado Highway 119 - Boulder Canyon will have single and full lane closures. During working hours, there will be up to five areas impacted concurrently.
Full Highway Closures
Monday through Thursday (August 19 - August 22) rock blasting activities will result in a full closure of Colorado Highway 119 from MP 39-40 between the hours of 10 a.m. to 2 p.m. Motorists entering the canyon from Nederland will be stopped at 9:45 a.m.  
24/7 Ongoing Impacts
Culvert installation will impact MP 36, and rock hauling will impact MP 40. Paving continues between MP 34 - 38. Motorists will be guided around the single lane closures with traffic control flaggers.
Three traffic signal zones will remain in place near MP 32, MP 38 and near MP 39, 24-hours a day, 7 days a week, to preserve the work areas.  
Up to 40-minute delays are expected through the canyon during work hours. Speed limits are reduced to 25 miles per hour in the construction zones. The work is weather-dependent, and the schedule may change. 
Please plan additional time to travel through the construction zones or to use the alternate routes of Colorado Highway 72 or Lefthand Canyon Drive during the full road closure. 
Trail Closure
The Boulder Canyon Trail, from the canyon mouth in Boulder to the Fourmile Canyon trailhead, will be closed, Monday – Thursday, 7 a.m. to 2 p.m. 
Creek Closure
The Boulder Canyon Creek will be closed for use from the canyon mouth in Boulder to the Fourmile Canyon trailhead, Monday - Thursday, 10 a.m. – 2 p.m. 

ALERT: Four Mile Resident Permits  

Residential permits remain available for residents who live on Four Mile Road, to maintain access to their homes from Nederland while the full closures are in place. If you live on Four Mile, and still need a permit, please call the project hotline. 

Unfortunately, Sugarloaf and Magnolia residents do not qualify for these permits. Local emergency service groups, in partnership with CDOT, cannot allow detour traffic over Fourmile/Poorman due to fears of construction congestion preventing emergency access.

Project Facts

  • Cost: $31 Million
  • Contractor: Zak Dirt
  • Timeline: Winter 2019 - Summer 2020
  • Location: CO 119 between Boulder and Nederland
  • Alternate Route During Construction: CO 72 is a recommended detour. Learn more about the CO 72 Coal Creek Canyon project.

In March 2019, crews began repairing a 15-mile stretch of Colorado Highway 119, between Boulder and Nederland, which was damaged during flooding in 2013.

Work includes:

  • resurfacing 13 miles of highway, and entirely replacing two miles of highway;
  • building concrete islands to improve the roundabout in Nederland;
  • installing new highway directional and safety signage;
  • replacing multiple pipes conveying stormwater drainage under the highway;
  • scaling rock in selected areas to reduce rockfalls on the highway;
  • repairing soft shoulder areas immediately adjacent the highway;
  • replacing 29,000 linear feet of concrete or metal guardrail;
  • removing and replacing materials placed during emergency repairs;
  • excavating areas where the slope had failed in the storm;
  • redesigning and widening specific sections of the roadway;
  • reconstructing embankments; and
  • re-establishing native grass seed and erosion control to slopes that were disturbed during emergency recovery work.

Boulder County Trail Improvements

The project, in partnership with Boulder County, will extend and reinforce sections of the Boulder Canyon Trail. The 10-foot-wide, multi-use trail will be extended from Four Mile Canyon to Chapman Drive—adding two new bike-friendly tunnels under the highway and approximately 3500 feet of length to the trail.

Project Work Hours:

  • 7 a.m. - 7 p.m., Monday - Friday
  • Rock-blasting work hours: 10 a.m. - 2 p.m., Monday – Thursday (April – August 2019)
  • No night or weekend work is planned. However, some work zones will remain closed to preserve the work area.

Travel Impacts & Delays

Various delays from single lane & full road closures are expected throughout the project.  Motorist are strongly encouraging everyone to plan ahead to give yourselves enough time to reach your destination.

  • Expect full highway closures for rock blasting and excavation, with four-hour complete closures.
  • Expect various long-term single-lane closures managed by temporary traffic signals, and various short-term single-lane closures managed by flagging.
  • Full Canyon Closures Monday through Thursday and 40-Minute Delays.
  • Speed limits will be reduced to 25 mph in the work zones. Expect several stops through the corridor.  
  • A permit-load restriction will be in effect.

Boulder Canyon Trail Impacts

  • April – August 2019
    • Crews will close the trail and parking areas adjacent to the trail (near mile point 40) when rock blasting is needed.
    • The trail could be impacted four times a week for nine hours at a time to allow for safe rock-blasting activities.
    • No weekend or holiday work is planned.
  • August - October 2019
    • The trail will be closed below the Boulder Canyon Trailhead at all times, including weekends and holidays.
    • Crews will place signage along the trail, at the opening of the canyon near Boulder City limits.

Updated Cycling Closures

To help keep everyone safe, the project team is continually monitoring the movement of vehicles and cyclists through the canyon and making adjustments as necessary. Starting Wednesday, July 3, cyclists will be allowed to travel in both directions of CO119 west of Fourmile Canyon Road. Project crews will be updating signage in the coming days. 

Between Fourmile Canyon Road and Arapahoe Avenue, all westbound cycling is restricted and eastbound travel is restricted between the hours of 9:45 a.m. and 2 p.m. Monday through Thursday. In this area all westbound cyclists and eastbound cyclists traveling between the hours of 9:45 a.m. and 2 p.m. on these days must use the Boulder Canyon Trail at all times. This is a safety measure to help keep the public safe in the busiest work area.

The Boulder Canyon Creek bike path is closed in both directions in the canyon from 6:45 a.m. to 2 p.m. Monday through Thursday. Due to the path's proximity to the blast area, this is a safety measure to make sure no pedestrians or cyclists are inside the blast zone during the day. 

If cyclists ride on Chapman Drive to CO119, they can now travel eastbound or westbound. Please note that anyone traveling eastbound on CO119 between 9:45 a.m. and 2 p.m. Monday through Thursday will be turned around at Fourmile Canyon Road. Additionally, the signalized closure for the barrier replacement work that’s occuring just east of Chapman Road is long and steep. This area could be difficult for less experienced cyclists. Cycling access remains open but is not advised in this area. 

There are no closures on the Betasso Canyon Link Trail. Cyclists can access this area from CO119, however, riders traveling from Boulder Monday through Thursday must be west of Fourmile Canyon Road by 6:45 a.m. to avoid the closure between Fourmile and Arapahoe Avenue.  

Boulder County is currently making improvements along Fourmile Canyon. At this time, all non-residential cycling is closed through the canyon. Please contact Boulder County for more information.

Contact Us

[email protected]
Text CO119 to 21000 to receive project text alerts.


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