Colorado Highway 119

About CO Highway 119

Colorado Highway 119, locally known as the Diagonal, connects Boulder to Longmont and travels through Gunbarrel and Niwot. Currently, there are 45,000 vehicles a day that travel along the corridor. There is a projected 25% increase in traffic by the year 2040. 

To address growing travel demand and provide improved mobility in the northwest region, RTD, along with the Northwest Mayors & Commissioners Coalition, completed the Northwest Area Mobility Study (NAMS) in 2014. The study determined a prioritized list of mobility improvements for the region. Implementing Bus Rapid Transit (BRT) along CO 119 was identified as a high-priority project.

In 2018, CO 119 carried 1,500 transit riders a day. Boardings are expected to increase by 33% with proposed multimodal improvements such as BRT.

Feasibility Studies and Results

In 2019, RTD completed the SH 119 Multi-Modal Planning and Environmental Linkages Study (PEL) to determine the feasibility of implementing BRT along CO 119. At the same time, Colorado Department of Transportation (CDOT) completed a Bikeway Study that resulted in preliminary bikeway concepts. During this process, RTD gathered public input through open houses, online comments and surveys. Three alternatives were proposed for BRT on the corridor: bus on the outside shoulder, bus queue bypass lanes and signal priority, and an inside managed lane. Following the Traffic Alternatives Analysis Study in 2021, CDOT decided to construct bus queue bypass lanes and intersection improvements at CO 52, Airport Road, and Hover Street.

Multi-Modal Corridor Vision
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Project Cost and Funding

Implementation of the full multi-modal corridor vision is estimated to cost $315 million. Currently, $104 million in funding has been secured for project elements such as BRT service/branding, new BRT stations, Coffman Street Busway, Business Access and Transit (BAT) lanes and bus queue bypass lanes throughout the corridor.

Multi-Modal Corridor Vision

Total Project Cost = $315M

Funded Project Elements (2020-2024)

  • BRT service
  • New BRT stations at 63rd Street, CO 52 and Niwot Road
  • Park-n-Rides at 63rd Street and Niwot Road
  • Bus queue bypass lanes at Jay Road, 63rd Street, SHCO 52, Niwot Road and Airport Road
  • Reconfiguring CO 52 and Airport Road intersections
  • Intersection safety and mobility improvements at Jay Road, 63rd Street, CO 52, Niwot Road and Airport Road
  • BAT lanes in Boulder
  • Coffman Street Busway (additional funding needed due to inflation in construction costs)

Secured Funding: $104M

  • RTD: $33M
  • DRCOG: $18M
  • CDOT: $50M
  • Boulder & Longmont: $3M

Unfunded Project Elements (Timing TBD)

  • Bikeway
  • Hover Street Intersection Improvements
  • Additional BAT lanes

Additional Funding Needed: $211M

Coffman Street Busway Project Map

City of Longmont Coffman Street Busway Project

The Coffman Street Busway project seeks to make Coffman Street, from 1st Avenue to 9th Avenue, a world-class, multimodal corridor to support residents, businesses, visitors, cyclists and pedestrians, commuters, the environment and the city.

Currently, the Coffman Street Busway project is developing design concepts, which will be evaluated against technical performance measurements and the Guiding Principles, which will be developed using community input.

Construction is not planned to start until 2023.

The project will have protected bike lands for safe bicycle travel, transit for less congestion, parking for local businesses and sidewalks and trees for a walkabout and vibrant community.

Boulder County CO 119 Bikeway Project

Boulder County is currently in the process of designing a paved-off street multi-use path along CO 119 between Boulder and Longmont. The CO 119 Bikeway project will optimize regional mobility between Boulder and Longmont by providing multimodal bicycle and pedestrian improvements that result in safer, more reliable, more comfortable and more appealing travel options.

The bikeway will provide a year-round, safe, direct, accessible and comfortable bike facility with seamless connections to transit, neighborhoods, businesses and local walking and bicycling paths.

The vision for the bikeway was first conceived in the Northwest Area Mobility Study and later studied in the 2019 Planning and Environmental Linkages (PEL). The overall corridor vision includes:

  • Bus Rapid Transit (BRT)
  • Intersection Improvements
  • Separated Bikeway Multi-Use Path
Conceptual View of the SH 119 Bikeway

CDOT and RTD CO 119 Safety and Mobility Improvements Project

The CO 119 Safety and Mobility Project is implementing queue bypass lanes, intersection improvements, new BRT stations and park-n-rides. Coupled with new RTD BRT service, these improvements will:

  • Cut bus travel times in nearly half 
  • Support greater travel flexibility by providing more frequent bus service
  • Provide a safer and more comfortable experience accessing the corridor on foot
  • Reduce fender benders and crashes
  • Enable vehicles to move through the corridor faster, with shorter wait times at traffic lights
  • Integrate BRT, Park-n-Rides, pedestrian crossings, and Boulder County’s Commuter Bikeway so commuters can switch travel modes safely and reliably.

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