CO 119 Boulder Canyon Improvements

Scheduling Update

Colorado Highway 119 Boulder Canyon full closure on Monday, Oct. 14 has been canceled. CO 119 will remain open all day with single-lane closures.

Colorado Highway 119 Boulder Canyon full closure for safety blasting Oct. 19

Colorado Highway 119 will be closed from MP 39-40 on Saturday, Oct. 19 at 8 a.m. through Sunday, Oct. 20 at 8 a.m., allowing project crews to safely remove a potentially unstable rock ledge above the Boulder Canyon. This 3,000 cubic yard blast is necessary to ensure the safety of Colorado 119 users and will require more clean-up than the regularly scheduled daily blasts.
In light of the start of the school year and bus operations, the Colorado Highway 119 team has scheduled this extended full closure over a weekend to minimize impacts as much as possible. During the extended closure, travelers are urged to avoid the Boulder Canyon route if possible. Local detours are available. 
From Boulder, a northern alternate route can be taken via CO 7, US 36 and CO 72. A southern alternate route is available via CO 93 and CO 72. Please note, motorists taking the southern alternate route should be aware of a current project on CO 72 in Coal Creek Canyon, between Plainview Road (mile point 12.3) and Pinecliffe (MP 24.6). A detour map is included below. Expect lane shifts and short delays in this work zone.

Work this Week

Tuesday through Thursday, 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.

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

There is currently a FULL CLOSURE of the Boulder Canyon trail at MP 40 where it crosses under CO 119, preventing through access from Boulder to the Four Mile trailhead. Crews will rehabilitate the highway structure and install underground rock protection for the next three months.  Eastbound cyclists will need to merge with CO 119 traffic through this area. Westbound cycling will be closed.

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 
  • 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 - December 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.

SH 119 Boulder Canyon Public Meeting Presentation

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