CO 119 Safety, Mobility and Bikeway Project - Construction Phase

About the Project:

CDOT, RTD, and Boulder County are excited to share details about the improvements coming to CO 119 that will make traveling through the corridor safer for all modes, as well as faster and more reliable for public transit.

Watch the online presentation videos below to more about the safety, mobility, and bikeway improvements. 

General Project Update

Unsignalized Intersections

Niwot Underpass

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 (CDOT), the Regional Transportation District (RTD), and Boulder County are taking action to mitigate these outcomes and expand transportation options beyond private automobiles.

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) will be used to build the project with construction scheduled to start in 2024.

Work this Week & Lane Closures
Coming in 2024

Project Facts

  • Construction Cost: $162M
  • Contractor: Kraemer North America
  • Timeline: Fall 2023 to Spring 2027
  • Location: Colorado Highway 119 (CO 119) between Boulder and Longmont*
  • Nearest Town/City: Between Boulder and Longmont
  • Mile Point(s): 44.5 to 54.5
  • County: Boulder

* This corridor is commonly referred to as “The Diagonal.” Southern limit is Foothills Parkway in Boulder and northern limit is Hover Street in Longmont. While the project limits do not extend beyond Foothills Parkway or Hover Street, the proposed Bus Rapid Transit routes extend beyond the corridor from downtown Boulder to Colorado Highway 66 north of Longmont.

Frequently Asked Questions

The following frequently asked questions were created based on the comments and questions received from the community and stakeholders at the CO 119 Safety, Mobility, and Bikeway Project public open house and online comment form that took place in December 2023 and January 2024.

Access Frequently Asked Questions for the CO 119 Mobility Project

Project Area

CO 119 Safety & Mobility Project Map

CO 119 Safety & Mobility Project Corridor Map

Project Improvements

  • New signage, striping, and improved signal timing at all pedestrian crossings.
  • Signal timing adjustments at key intersections (Jay Road, 63 rd  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 roadways.
  • Changing access at Airport Road and CO 119 to reduce crashes and to improve safety and traffic flow.
  • Hover Street intersection will be improved through a separate project.
  • BRT improvements:
    • Park-n-Rides at 63 rd  Street and Niwot Road.
    • Within the project limits, new BRT stations at 63 rd  Street, CO 52, and Niwot Road.
    • Queue Bypass Lanes at Jay Road, 63rd Street, CO 52, Niwot road, and Airport Road
    • The map also shows the BRT routes proposed for the corridor.
    • The Blue Line runs every 15 minutes, and the Orange Line runs every 30 minutes.
    • A list of all stops associated with the proposed BRT service is available here.

Project Goals

CO 119 Safety & Mobility Goals graphic
CO 119 Safety & Mobility 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

  • Less fender benders and crashes
    Vehicles can move through the corridor faster, with shorter wait times at traffic lights
  • 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

Next Steps and Project Schedule

  • Reviewing and optimizing the proposed design.
  • Planning out the potential phasing of construction.
  • Determining how the design will be packaged for construction.
  • Establishing a schedule for construction.
  • Starting construction in 2024.

Traffic Impacts:

  • More information will be provided prior to construction.