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Project Overview

28th Street is a state highway (US 36) and a gateway to Boulder for employees, visitors, students, and local residents. Corridor planning began in the early 2000s, with a cutting-edge Complete Streets design which has since evolved to sync with other regional projects and to support the community’s current and future transportation needs.

Once the project completes work between Iris Avenue and Canyon Boulevard, 28th Street from Iris Avenue to Baseline Road will be transformed into a multimodal corridor with a consistent design that delivers transportation, safety, aesthetic and economic improvements.

Project Update

Project construction on 28th Street from Iris Avenue to Canyon Boulevard began in early 2025, following the completion of utility relocations that accommodate the project design. We anticipate completing construction by mid-2026.

Visit Cone Zones for construction and traffic impacts.

Timeline

  • 2017-2024: Community Engagement.
  • 2017-2018: Preliminary design; grant funding awarded.
  • 2020-2021: Final Design.
  • 2025-2026: Construction.

Canyon Boulevard to Iris Avenue

Canyon Boulevard to Iris Avenue is the final segment of 28th Street to receive improvements as part of this corridor-wide improvement effort. The project received funding because the corridor is a primary state highway through Boulder and a high-crash corridor, and the planned improvements will increase safety for all users and enhance transit service along the corridor.

A key component and goal for this project is to maintain the continuity of corridor-wide design by matching this segment to the segments of 28th Street to the north and south. Decisions about the corridor-wide design were made during the preliminary design phase, which included community input.

The following improvements will be constructed along this segment:

  • Bus and turn lanes in each direction along 28th Street. The curbside lanes on 28th Street will be repurposed to a bus and turn lane where not already operating as such, and may be used by buses and right-turning vehicles. Bus and turn lanes offer several benefits:
    • People driving have fewer conflicts with the bus as it makes frequent stops, providing safety benefits.
    • Turning right at intersections and into driveways is easier and safer because bus and turn lanes provide better visibility and opportunity to turn, improving business access.
    • Travel is more reliable for vehicles using the general-purpose lanes, as they are no longer delayed by turning vehicles or buses.
    • Travel time for buses is faster and more reliable.
  • Bus stop improvements to accommodate future CO 119/Diagonal Bus Rapid Transit (BRT) service.
  • Closure of gaps in the existing multi-use paths on both sides of 28th Street to create continuous ten-foot-wide paths, including raised driveway crossings. Colored conflict markings will be added where warranted.
  • Installation of landscape areas between the street and the multi-use paths, where feasible. Street trees will also be added throughout the corridor, where feasible.
  • Replacement of traffic signals on 28th Street at Mapleton Avenue and Glenwood Drive.
  • At Pine Street, addition of a raised north/south crosswalk and curb extensions to slow vehicle turning speeds, increase driver awareness of people crossing, and shorten pedestrian and bicyclist crossing distances. An extended median on 28th Street will be constructed and Pine Street will become right-turn in and out only. This will eliminate a crash pattern associated with left turns at this intersection and reduce the risk of conflicts in the crosswalk.
  • Storm drainage upgrades and utility relocations.

CO 119/Diagonal Project Integration

The 28th Street improvements will sync with the regional CO 119/Diagonal Bus Rapid Transit (BRT) Project, which will include the addition of bus lanes and a paved bikeway from Boulder to Longmont. The CO 119 BRT will serve 28th Street stops at Iris Avenue (CO 119), Valmont Road, Spruce Street and Canyon Boulevard in conjunction with the 28th Street Improvements Project.

Goals

The primary purpose of the project is to enhance regional bus service on 28th Street, which is one of the busiest corridors in the city. 28th Street connects CU Boulder, the Twenty Ninth Street retail district, Boulder Junction, local and regional transit routes, and the multi-use path system. The improvements strengthen multimodal travel throughout the region and allow the future CO 119/Diagonal Bus Rapid Transit (BRT) service between Boulder and Longmont to run on 28th Street.

The project will provide multimodal transportation options to accommodate safer travel for people walking, rolling, biking, taking the bus, and driving. The project will close gaps in the multi-use paths along both sides of 28th Street to create continuous north-south multi-use paths from Baseline Road to Iris Avenue, as recommended in the city’s Low-Stress Walk & Bike Network Plan.

The improvements expand travel options for people commuting into and out of Boulder and for employees of 28th Street businesses by providing roadway enhancements, a continuous multi-use path for people walking, rolling, and biking, better lighting, improved transit stops, and continuous and efficient future Bus Rapid Transit service via the bus and turn lanes.

Drought-resistant landscaping such as fertile grasses, shrubbery and trees requires little maintenance. The new irrigation system and wood mulch dramatically reduce water loss, surface runoff and weed growth. This system is designed to allow the city to selectively irrigate portions of the landscaping in possible drought conditions.

The improvements on 28th Street encourage private investments by improving access to businesses and adding value to existing commercial centers, such as the Twenty Ninth Street retail district.

This project supports the Core Arterial Network (CAN), the connected system of protected bicycle lanes, intersection enhancements, pedestrian facilities, and transit facility upgrades that will help reduce the potential for severe crashes and make it more comfortable and convenient for people to get where they need to go along Boulder’s main corridors. It also supports the city’s commitment to Vision Zero – the goal to reduce the number of traffic-related fatalities and serious injuries to zero.

FAQs

The primary purpose of the project is to enhance regional bus service on 28th Street, which is one of the busiest corridors in the city. From Iris Avenue to Pearl Street, the project will add continuous bus and turn lanes on 28th Street, which may be used by buses and right-turning vehicles. Bus and turn lanes improve travel for all by reducing vehicle conflicts with buses, making right-turns at intersections and driveways easier and safer for all travelers, improving business access, and speeding up transit travel times while supporting reliable travel times for people driving. The project will also improve bus stops on both sides of 28th Street. These enhancements will allow the future CO 119/Diagonal Bus Rapid Transit (BRT) service between Boulder and Longmont to run on 28th Street.

BAT lane
A rendering shows 28th Street with two vehicle travel lanes and a bus and turn lane. The bus and turn lane has “Bus Only” and right-turn pavement markings. People are walking and biking on the multi-use path and people are waiting for the bus in a large bus boarding area.

In addition, the project will close gaps in the existing multi-use paths on both sides of 28th Street to create continuous ten-foot-wide paths from Baseline Road to Iris Avenue. This improvement is consistent with recommendations from the city’s Low Stress Walk & Bike Network Plan.

28th Street multi-use path
A rendering shows 28th Street with a 10-foot wide multi-use path, a bus and turn lane, and two vehicle travel lanes. People are walking and biking on the multi-use path. A bus driving in the bus lane and a private vehicle is making a right turn into a driveway from the bus and turn lane.

Benefits include more convenient and reliable transit service, including increased transit efficiency for the future CO 119/Diagonal BRT service. The project will provide additional travel choices for people commuting into and out of Boulder as well as employees of 28th Street businesses, one of the main commercial centers in the city. Additionally, the project will provide enhanced bicycle and pedestrian access along 28th Street with the installation of a continuous 10-foot-wide multi-use path on each side of the street. The project also supports the Core Arterial Network, the connected system of protected bicycle lanes, intersection enhancements, pedestrian facilities, and transit facility upgrades that will help reduce the potential for severe crashes and make it more comfortable and convenient for people to get where they need to go along Boulder’s main corridors.

This project is the last phase of a larger project that first launched in the 1990s and aimed to improve transportation on 28th Street between Baseline Road and Iris Avenue. 28th Street was chosen for improvements because it is one of the busiest corridors in Boulder, a major north-south connection serving many residents, commuters, and visitors, and a major center for retail and business. Additionally, 67% of crashes in Boulder that result in serious injury or fatality occur on our arterial streets, like 28th Street, according to the city’s Safe Streets Report. These factors, along with the recommendations from the Low Stress Walk and Bike Network Plan, make it a top candidate for travel enhancements.

As outlined in the city’s Transportation Master Plan, increasing transit capacity is key to meeting the needs of the Boulder community and all who live, visit, work and play here. The improvements on 28th Street will allow the corridor to provide future CO 119/Diagonal Bus Rapid Transit (BRT) service. This will help many current commuters who travel between Boulder and Longmont by car to switch to faster and more convenient transit service. Improving regional travel connections and providing more attractive, non-vehicular options for commuting is key to decreasing greenhouse gas emissions, meeting our city's Climate Commitment goals and providing more comfortable, efficient and convenient travel for all, no matter their mode of travel.

This project will increase transit service capacity by adding bus and turn lanes, improve regional travel options, and close gaps in the multi-use path system, all key goals of the city’s Transportation Master Plan and Low-Stress Walk and Bike Network Plan. It also supports the Core Arterial Network and Vision Zero Action Plan.

The bus and turn lanes being added to 28th Street will be used only by buses and right-turning vehicles, which will reduce conflicts between buses and through traffic. Currently, buses are required to merge with all other vehicles at multiple points along the corridor, reducing efficient bus travel and adding potential conflict points. The multi-use paths added along both sides of 28th Street will be complemented by raised driveway crossings, warning signage at driveway exits and colored conflict markings, all of which will increase safety and visibility for people traveling on and across the multi-use paths. This design aligns with current Vision Zero best practices intended to increase safety.

Additional safety enhancements include:

  • Reconstruction of the 28th Street/Mapleton Avenue and 28th Street/Glenwood Drive intersections to improve left-turn signal timing.
  • Addition of center medians on 28th Street at the 28th Street/Mapleton Avenue and 28th Street/Glenwood Drive intersections to better delineate vehicle travel lanes.
  • At Pine Street, addition of a raised north/south crosswalk and curb extensions to slow vehicle turning speeds, increase driver awareness of people crossing, and shorten pedestrian and bicyclist crossing distances. An extended median on 28th Street will be constructed and Pine Street will become right-turn in and out only. This will eliminate a crash pattern associated with left turns at this intersection and reduce the risk of conflicts in the crosswalk.
  • Evaluation of corridor traffic signals where Pedestrian Head Start signal timing could be added. Pedestrian Head Starts give people crossing a 3-7 second head start to enter the crosswalk before the light turns green for vehicles. This increases the visibility of people crossing and establishes their right-of-way, and can reduce pedestrian-vehicle collisions by as much as 60%.
  • Evaluation of vehicle turning movements to understand if any locations would benefit from right-turn-on-red restrictions or other traffic signal modifications.

A curbside lane (already striped as a bus lane in some areas) currently exists on the majority of the project corridor. This project will repurpose portions of the existing curbside lane into a bus and turn lane and expand the bus and turn lane where only two lanes currently exist to create an uninterrupted lane prioritized for bus service and right-turns. The bus and turn lane will not increase vehicle capacity along the corridor; rather, it will allow for better access to businesses along 28th Street and improve the convenience and attractiveness of transit service. Staff do not anticipate that this project will result in any noticeable increase in vehicle speeds, but will continue monitoring speeds along the corridor prior to and after project implementation.

These improvements are funded by a number of sources, including $1.3 million in city transportation funds and $4.7 million from the Denver Regional Council of Governments (DRCOG) Transportation Improvement Program (TIP).