The CO 119 Safety, Mobility and Bikeway Project is creating a nine‑mile, off‑street path between Boulder and Longmont, along with intersection safety upgrades and new bus rapid transit stations. Boulder County, CDOT, RTD, the Cities of Boulder and Longmont, and Commuting Solutions are collaborating to ensure the project reflects regional priorities and community needs.
Diagonal Highway 119 Bikeway Design Project
The CO 119 Safety, Mobility and Bikeway Project is the development of a nine‑mile, off‑street path between Boulder and Longmont, giving cyclists and pedestrians a safer, more sustainable way to travel. Boulder County, CDOT, RTD, the Cities of Boulder and Longmont, and Commuting Solutions are collaborating to guide the project and ensure it reflects regional priorities and community needs.
Construction on the Project is Happening!
Construction is expected to be completed January 2027. The completed project will include:
- Improved safety for motorists, cyclists, and pedestrians.
- Faster and more reliable bus service between Boulder and Longmont.
- Park-n-Rides at 63rd Street and Niwot Road, and bus stops at CO 52.
- Safety improvements at many of the intersections.
- A nine-mile-long paved bikeway.
Diagonal Construction Progress
The bikeway underpass at CO 119 and CO 52 was constructed without any road closures because it was built to the side of the existing intersection. The CO 119 southbound lanes will be shifted closer to IBM Drive to create a median for the bikeway.
Background music only, no spoken words. This short video starts at the Diagonal and Jay Road and shows the bikeway underpass, the sidewalk, buffered bike lane on Jay and the two newly restored left hand turn lanes from Jay to Boulder bound CO 119, a gap where the bikeway is not yet built and then towards 55th where there is another section of constructed bikeway.
The intersection of the Diagonal and CO 52/Mineral Road looks really different than it did just last year. This photo shows the road alignment, the white concrete section in the upper left part of the photo is going to be the new north bound bus rapid transit stop. The bikeway underpass is also visible in the middle of the photo.
Underpass where the bikeway leaves the median and connects to an existing path in Longmont to connect to the existing path. The Spirit of Longmont sculpture is visible in the background.
View of the bikeway underpass at CO 119 and CO 52. This underpass was built from concrete made on site using a method called cast in place. 
The bikeway underpass at CO 119 and CO 52 was constructed without any road closures because it was built to the side of the existing intersection. The CO 119 southbound lanes will be shifted closer to IBM Drive to create a median for the bikeway. 
Jay Road needed to be closed to construct the Jay Road bikeway underpass. Before the underpass was constructed, waterproofing material was installed.
Jay Road needed to be closed to construct the Jay Road bikeway underpass. In order to open the road as quickly as possible, the underpass was constructed using precast pieces of concrete that were made elsewhere and then trucked to the site. More Information
Underpasses and Overpasses
Bikeway underpasses will be constructed at Jay Road, CO 52 (Mineral Road), and Niwot Road. An overpass will be constructed at 63rd.
Rapid Transit Stations
Bus Rapid Transit Stations at 63rd Street and Niwot Road including the bikeway overpass at 63rd Street and the Bikeway underpass at Niwot Road. All three stops will have bike-n-ride shelters. The Bikeway will have underpasses at Jay Road, Niwot Road, CO 52 (Mineral Road) and to connect to an existing path in Longmont.
The CO 119 Bikeway Design Validation Memo was a refinement of the Conceptual Design.
The Concept Plan, which was funded by CDOT, was completed in 2019. The Concept plan included the first draft of an alignment for the Bikeway. Once the County secured funding through a Denver Regional Council of Governments grant, the plan was presented to the public via a video public meeting. The public shared thoughts, concerns, and ideas during the meeting, through comment forms and through an online survey. These comments are being incorporated into the next step in the design process.
In 2019, a Planning and Environmental Linkages (PEL) report was completed which identified the multi-modal corridor vision for CO 119. This vision includes:
- Bus Rapid Transit (including Park-n-Rides, new stations, Business and Transit lanes, Transit Signal Priority/queue jump lanes)
- Intersection Improvements
- BRT/Managed Lanes
- Separated Bikeway
In 2014, The Northwest Area Mobility Study (NAMS) was completed. The NAMS report includes a prioritized list of mobility improvements for the Northwest area of the Regional Transportation District’s (RTD) service area. CO 119 was identified as the top priority corridor for improving mobility in Boulder County and included recommendations for Bus Rapid Transit and a separated bike facility.
This collaborative effort included RTD, the Colorado Department of Transportation (CDOT), the Denver Regional Council of Governments (DRCOG) and the Northwest Area Stakeholders: 36 Commuting Solutions, City of Arvada, City of Boulder, Boulder County, City and County of Broomfield, City of Lafayette, City of Longmont, City of Louisville, North Area Transportation Alliance (NATA), Town of Superior, University of Colorado, and City of Westminster. View more information on the Commuting Solutions website.
The CO 119 First and Final Mile Study published by Commuting Solutions provides solutions to connect users to a BRT (Bus Rapid Transit) and bikeway. The study discusses the challenges, such as the first or final mile gap which describes how users are often discouraged to use transit due to distances. This study also discusses how to create a user-friendly network for people walking or biking to future BRT stations.
A new approach to outreach: The county knows that the best bikeway is designed to accommodate many different types of people. We have broadened the way we do outreach so we can receive comments and feedback from a larger diversity of voices. To strive for this broader outreach, we have met with bicycle and mobility advocacy organizations and businesses along the corridor. We have added Spanish interpretation to our virtual public meetings and are making a concerted effort to provide written materials in Spanish. We have also created two advisory committees.
Community Advisory Committee
Community Advisory Committee members were chosen via an application process. The seats represented on the committee are:
- Community member who resides or works in or near Longmont
- Community member who resides or works in or near Boulder
- Community member who resides or works in or near Niwot or Gunbarrel
- Business owner on or near the corridor that employs workers with transportation challenges
- Employee on or near the corridor who has transportation challenges commuting to work
- Cyclist who uses or crosses the corridor as part of their regular bike commute route
- Recreational cyclist
- Current public transit user along the corridor
- Person with mobility challenges
- Liaison from Spanish language Equity Committee
Spanish Language Equity Committee
The Spanish Language Equity Committee is made up of 8 members from the County’s Spanish speaking community and was created to help the county’s outreach efforts reach our Spanish speaking residents.
Summary of Public Input in 2021
During the first phase of the CO 119 Bikeway Design Project in Summer/Fall 2021, the public provided questions and comments covering an array of topics through the Public Meeting on Aug. 30, online comment forms, and public surveys. The CO 119 Bikeway Project Public Input document summarizes this input alongside commentary and responses from the Project Team.
The SH 119 Bikeway Project location stretches between Longmont and Boulder along Diagonal Highway 119.
Project schedule timeline infographics:
Boulder County is working closely with CDOT, RTD, the Cities of Boulder and Longmont and Commuting Solutions so the bikeway and the Mobility Project and the PEL for CO 52 work seamlessly together for all travelers.
The map below of SH 119 Bikeway Project’s coordination with other projects being conducted along the main line of the SH 119 corridor by RTD, the state, Commuting Solutions, the Cities of Boulder and Longmont.
More Information:
CO 119 Bikeway 63rd St. Overpass Open House on Sept. 10, 2024
A public in-person open house was held in Gunbarrel on the planned overpass and the future Gunbarrel Shuttle service.
Public Webinar Aug. 13, 2023
Public In-person Open House Dec. 13, 2023
CO 119/Diagonal Safety, Mobility and Bikeway Public Open House Niwot Grange Dec. 13 2023.
Boulder County’s Community Planning & Permitting Department, the Colorado Department of Transportation (CDOT), and the Regional Transportation District (RTD) hosted an open house on Dec. 13, 2023. More than 60 attendees discussed the project with CDOT, County and RTD staff and viewed boards
displaying graphics of the proposed unsignalized intersection safety improvements at 55th Street, Monarch Road, Oxford/83rd Street and Fordham Street. Attendees also viewed boards displaying graphics of three underpass options that would connect the bikeway to downtown Niwot.
In response to the many questions asked during the meeting and collected via online comment forms an Frequently Asked Questions (FAQ) was developed.
Boulder County Board of Commissioners public hearing: 119 Bikeway and the Safety and Mobility Improvements Project, April 20, 2023
The Board of County Commissioners held a public hearing on April 20, 2023, for the 119 Bikeway and the Safety and Mobility Improvements Project. View the recording of the April 20, 2023 BOCC meeting.
Boulder County Planning Commissioners public hearing: Docket SI-22-0002, March 15, 2023
On March 15, 2023, the Boulder County Planning Commission held a public hearing on Docket SI-22-0002. The Planning Commission recommended that the Board of County Commissioners approve the project with the staff conditions. View the recording of March 15, 2023 BOCC meeting.
Boulder County staff reviewed the project details and determined that the 119 Bikeway and the Safety and Mobility Improvements Projects do not pose a hazard to any aspect of the environment listed in the Areas and Activities of State Interest (1041) Review and that the projects will support and help achieve many goals in the County Comprehensive Plan including (but not limited to):
- Air quality goals; Public Health Goal 1.01
- Open Space and Nature; Public Health Goal 2.01
- Multimodal transportation; Public Health Goal 3.04
- Address Climate Change; Public Health Goal 7
- Provide a Multimodal Transportation System; Transportation Goal 1
- Design Complete Corridors; Transportation Goal 1.02
- Enhancing the bicycle and pedestrian network; Transportation Goal 1.03
- Establishing Connections to Development; Transportation Goal 1.05
- Support fast, frequent, affordable, and reliable transit service between communities; Transportation Goal 1.06
- A transportation system that moves people safely and effectively independent of an assumed mode of travel; Transportation Goal 4
- Ensure Transportation System Access for Low-Income, Elderly, & Mobility Impaired Populations; Transportation Goal 9
The 119 Bikeway and Safety & Mobility Projects team submitted an Areas and Activities of State Interest application to Boulder County in December 2022. This application is also known as a 1041 Review. View more information and public meeting information on the Docket SI-22-0002: Safety and Mobility and Bikeway Projects webpage.
The purpose of the review ensures that all design and construction planned for the 119 Bikeway and the Safety and Mobility Improvements Project are in agreement with Boulder County’s Comprehensive Plan.
The 1041 review assessed all the environmental documentation and other details already collected and confirm that it does not conflict with the Boulder County Comprehensive Plan (BCCP). The Comprehensive plan was developed to respond to the widely accepted principle that the myriad of future land use decisions affecting the county’s lands should be made in a coordinated and responsible manner.
This application/review allows the Boulder County Planning Commission and the County Commissioners to conduct public hearings and review the application according to the criteria in the Code. At that time, all public input, including emails opposing the project, will be made a part of the record of the 1041 docket and considered by the Planning Commission and the County Commissioners as a part of their decision-making processes.
CO 119 Diagonal Highway Transportation Project Community Meeting, June 27, 2022
Boulder County’s Community Planning & Permitting Department, the Colorado Department of Transportation (CDOT), and the Regional Transportation District (RTD) hosted a community meeting on June 27, 2022 on the dual transportation projects currently being designed for Colorado Highway 119 between Boulder and Longmont (The Diagonal Highway). The featured projects include the CO 119 Commuter Bikeway Design Project (Boulder County) and the CO 119 Safety and Mobility Project (CDOT and RTD). The meeting included a presentation by project team members on design plans and an overview of how the two projects work together to improve safety and enhance multimodal connectivity on the corridor.
Board of County Commissioners (BOCC) Town Hall Webinar on the Diagonal Highway 119 Makeover, April 14, 2022
Boulder County residents were invited to join the Board of County Commissioners for a Town Hall meeting about the Highway 119 (Diagonal) Makeover. After a presentation by staff from the Transportation Planning Unit of Boulder County Community Planning & Permitting, attendees were encouraged to ask questions in the Q&A feature of Zoom about the project. Commissioners also fielded public comments on general transportation issues.
Virtual meeting on the CO 119 (the Diagonal) Bikeway Design, Aug. 30, 2021
Boulder County’s Community Planning & Permitting Department and CDOT invited the public to a virtual meeting presentation on the CO Highway 119 Bikeway Project on Aug. 30, 2021. Staff discussed the conceptual design of the bikeway and potential connections at the north and south ends of the project. Participants had an opportunity to ask questions and provide feedback on the design concepts at the meeting.
Project Manager
Stacey Proctor
Community Planning & Permitting
Email: sproctor@bouldercounty.gov
Phone: 303-441-1107