CO 119 Safety, Mobility & Bikeway | Construction Phase

About the Project:

By the year 2040, the Diagonal Highway between Boulder and Longmont is expected to see a 25% increase in vehicular traffic. Increased traffic can result in more congestion, delay, tailpipe emissions, and potentially more crashes. The Colorado Department of Transportation, the Regional Transportation District, and Boulder County are taking action to mitigate these outcomes and expand transportation options beyond private automobiles.

To sign up for the weekly construction update emails, follow these steps:

• Select the "Sign up for CO 119 Mobility Project Updates" button on the right side of the page
• Scroll to the "Construction Updates & News Releases" section, select "Subscribe to Construction Updates"
• Enter your email address, select "Northeast Colorado" as the region, check "Front Range I-25 Corridor" and "CO 119 Safety & Mobility Improvements"
• Submit!

The CO 119 Safety, Mobility and Bikeway Project is constructing improvements to make traveling through the corridor safer for all modes and transit travel faster and more reliable. The project is designed to integrate with other active multimodal projects on the corridor to ensure community members can safely and reliably travel throughout the corridor using their mode(s) of choice.

Funding has been secured for implementation of the project and a Construction Manager/General Contractor (CM/GC delivery method) will be used to build the project. Construction started in September 2024.

Watch the online presentation videos below to learn more about the safety, mobility, and bikeway improvements. Email [email protected] if you wish to receive this presentation in Spanish.

General CO 119 Safety, Mobility & Bikeway Project Updates

Niwot Underpass

Project Area

Key features include:

• Bus Rapid Transit (BRT) Stations: Marked with red bus icons along CO 119.
• Park-n-Ride Locations: Indicated with blue "P" icons at various stations.
• Operational & Safety Improvements: Shown with green intersection icons.
• Bus Queue Bypass Lanes: Denoted with a gray bus with a green arrow.

Proposed RTD BRT Routes:

• Blue Line: Proposed with a 30-minute frequency between Boulder and Longmont, bi-directionally, weekdays and Saturdays: 6 a.m. to 9 p.m. and Sundays 7 a.m. to 7 p.m. Hourly service frequency earlier and later are also proposed to be provided.
• Orange Line: Proposed with a 30-minute frequency between Boulder and Longmont, bi-directionally, weekdays in the peaks only (6 a.m. to 10 a.m. and 2:30 p.m. to 6 p.m.)
• Routings of these two patterns will slightly vary within Boulder and Longmont.

Additional features:

• Intersection reconfiguration at Mineral Road.
• Northern and Southern Project Limits marked in Longmont and Boulder respectively.

Major roads and highways are also labeled, including Airport Road, Hover Street, Niwot Road, Mineral Road, Lookout Road, Jay Road, CO 52, CO 119, and CO 157.

Project Improvements

• New signage, striping, and improved signal timing at all pedestrian crossings at signalized intersections.
• Signal timing adjustments at key intersections (Jay Road, 63rd  Street, CO 52, Niwot Road, and Airport Road).
• Physically reconfiguring the CO 52 intersection to improve safety and to accommodate new Bus Rapid Transit (BRT) stations and Boulder County’s Commuter Bikeway between the northbound and southbound travel lanes.
• Changing access at Airport Road and CO 119 to reduce crashes and to improve safety and traffic flow.
• A list of all stops associated with the proposed BRT service is available here.

Project Goals

• Improve safety in the whole corridor
• Maximize the number of people able to move through the corridor
• Maximize intersection operational efficiency
• Improve transit travel times and increase ridership
• Maximize corridor-wide operational efficiency
• Increase opportunities for bicycle commuting and connectivity to the bicycle and pedestrian network.

Project Benefits

• Vehicles can move through the corridor faster, with shorter wait times at traffic lights, resulting in less fender benders and crashes
• Traveling the corridor by bus will take about half the time it currently does
• More frequent bus service supports greater travel flexibility
• Safer and more comfortable experience accessing the corridor on foot
• Integration between Bus Rapid Transit, Park-n-Rides, pedestrian crossings, and Boulder County’s Commuter Bikeway enables commuters to switch travel modes safely and reliably

Project Schedule

• Construction began in September of 2024
• The project is scheduled for completion in Spring of 2027

Traffic Impacts:

For the week of Dec. 22 to 28 and Dec. 29 to Jan. 4, 2025

There will be no construction activity on the corridor Tuesday, Dec. 24 to Wednesday, Dec. 25 and on Wednesday, Jan. 1 for the holidays. Although work will not be happening, please continue to drive safely through the construction zone. Have a safe and happy holiday season!

Construction Impacts:

• Beginning at 9 p.m. Friday, Dec. 20 to 5 a.m. Monday, Dec. 23, eastbound Jay Road at Colorado Highway 119/Diagonal Highway will be closed to all modes of transportation. Westbound Jay Road will remain open. This closure is required for crews to begin waterline installation work. There is a separate detour for cyclists.
• Eastbound Jay Road traffic will travel south on CO 119, keep right at the Colorado Highway 157 intersection and turn left onto northbound CO 119 and return to Jay Road.
• Eastbound cyclists will travel south on 47th Street, turn left to travel east on Independence Road and head north on 57th Street to return to Jay Road.
• Thursday, Dec. 26 to Friday, Dec. 27, 7 a.m. to 5 p.m., there will be various shoulder closures along CO 119/Diagonal Highway between CO 157/Foothills Parkway and South Pratt Parkway to install in-ground construction signs.
• Beginning Friday, Jan. 3, crews will permanently modify the configuration of the Monarch Road median, in between northbound and southbound CO 119/Diagonal Highway, to all travelers and modes of transportation. Travelers can use Niwot Road to access Monarch Road on the east or west side of CO 119. Once modified, Monarch Road will be reconstructed into a right-in/right-out intersection at CO 119.
• After carefully considering and reviewing the traffic crash data from the high number of severe crashes that have occurred here, the project’s engineers and traffic staff, in partnership with Boulder County, ultimately decided to close the Monarch Road crossing at CO 119/Diagonal Highway. This closure is essential to constructing a safer CO 119 corridor for the community.
• Motorists are experiencing travel delays due to a temporary lane closure at the intersection of Jay Road and CO 119/Diagonal Highway. The project team is aware of the delays and continues to monitor the intersection. The Jay Road intersection will remain in this configuration through early 2025, and the project team advises that travelers take alternate routes at this time.

Thank you for your patience and understanding as crews work diligently to complete this project as safely and efficiently as possible. These lane shifts are necessary to facilitate essential improvements that will ultimately enhance traffic flow and safety for everyone.

Traffic-pacing Operations

Intermittent traffic-pacing operations will occur on CO 119/Diagonal Highway throughout construction while crews move equipment across the highway. Traffic will move slower and may result in brief traffic holds for a couple of minutes as a part of this work. Please be patient and do not pass the traffic-pacing vehicles — passing them poses a safety risk to all drivers on the road. Thank you for your patience!

Help Ease Traffic: Explore Alternative Transportation during Construction

Hey, drivers! We know construction along CO 119/Diagonal Highway can be a hassle, and we're working hard to improve this corridor for everyone. In the meantime, we encourage the use of alternate modes of transportation to help reduce traffic and make your commute easier. Whether it’s carpooling, biking or using public transit, every little bit helps ease congestion and keep things moving smoothly for everyone.

Thanks for your patience and support – we’ll get there faster together!