Iris Avenue Transportation Improvements Virtual Open House 3

Welcome! ¡Bienvenido!

July 19, 2024 — Transportation and Mobility Department

Welcome

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Goals of the Open House

Help us make travel on Iris Avenue between Broadway and 28th Street safer, more comfortable, and connected, no matter how you get to important community destinations.
Learn about the work that has been completed since the last open house in Spring 2024.

✓ What we’ve done since the last open house

We’ve completed the alternatives evaluation.
A recommended alternative has been identified.

Share your thoughts on the alternatives’ evaluation and recommended alternative.

Do the Community and Environmental Assessment Process (CEAP) and project specific evaluation criteria adequately assess the alternatives?
Is there anything we missed or haven’t yet considered?

WHERE ARE WE IN THE PROCESS?

The timeline infographic for the Iris Avenue Transportation Improvements project shows that Community Engagement happens throughout the life of the project. Corridor Analysis took place Summer through the Winter of 2023, Initial Screening took place in the Winter of 2024, Alternatives Development happened from the Winter through the Spring of 2024, and Conceptual Alternatives were shared in the Spring of 2024. The current phase in the project is selecting a Recommended Alternative in Summer 2024. The future phases of the project that remain are the City Council review in the Fall of 2024 and Final Design and Construction, which has a pending timeline.

About the Project

The Iris Avenue Transportation Improvements Project will identify and implement ways to make Iris Avenue between Broadway and 28th Street safer, more comfortable, and connected.

This map shows the core study area on Iris Avenue from Broadway to 28th Street. It also shows the secondary study area that extends north from Iris Avenue to roughly Norwood Avenue and south to Balsam Avenue/Edgewood Drive. The map highlights that the improvements at the bookends of the corridor from roughly Elmer’s Two Mile Trail to 28th Street and roughly 13th Street to Broadway will not impact the existing vehicular travel lane configuration. End-to-end improvements within the core study area include protected bike lanes as well as sidewalk and bus stop upgrades. There are four conceptual design alternatives developed between 13th Street and Folsom Street/26th Street.

This project will develop improvements focused on:

This map provides a zoomed-out view of Boulder, spanning from Table Mesa Drive in the south to Jay Road in the north, with boundaries along Broadway to the west and 61st Street to the east. It identifies the Core Arterial Network (CAN) streets. Broadway, Colorado Avenue, Arapahoe Avenue, 30th Street, and 61st Street are identified as CAN corridors. The downtown area is also highlighted as part of CAN. Iris Avenue, Baseline Road, Folsom Street are noted as Priority CAN corridors. 13th Street and 28th Street are noted as having corridors with existing enhancements. Arterial streets and key multi-use paths are also marked and identified on the map for easy reference.

Increasing mobility choices.
Improving safety for everyone.
Making walking, bicycling and taking transit more attractive and convenient.
Improving connections to local and citywide destinations.

Iris Avenue is the second of three priority corridors in the city’s Core Arterial Network (CAN) initiative.

What is the CAN initiative?

The CAN is a connected system of safe multimodal streets with protected bicycle lanes, intersection enhancements, pedestrian facilities, and transit facility upgrades. This connected system 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. The CAN initiative is one of City Council’s top priorities.

IRIS AVENUE IN CONTEXT

Why do anything to Iris Avenue?

Iris Avenue has five of the six risk factors that account for the most frequent and severe crashes. These factors place Iris Avenue from 19th to 28th Streets on the high risk network.

Infographic showing factors that place Iris Avenue on the high-risk network including: Daily vehicle traffic between 5,000 and 10,000 per travel lane, signalized intersections, major unsignalized intersection, businesses and a mix of land uses present, and 85 percent of vehicle speeds at or above 30 miles per hour.

City plans, federal guidance and community input call for proactive safety improvements to make Iris Avenue safer, and more comfortable and connected for everyone, including people biking. The below reasonings show why doing nothing is not an option.

Infographic showing City plans, federal guidance and community input for Iris Avenue. City of Boulder recommendations include the City’s 2019 Low-Stress Walk and Bike Network Plan which recommends protected bike lanes for Iris Avenue and to create more space between vehicle lanes and people walking. The Federal Highway Administration does not recommend removing an existing bike lane from a street. We’ve also heard from hundreds of members of the community that Iris Avenue feels unsafe regardless of mode of travel, vehicle speeding is an issue, and the street is too nosy and uncomfortable.

Why not direct people biking to parallel streets instead?

Parallel routes can offer lower stress bike connections for some of these trips, but are not always direct and so do not serve all trips.

I wish there was more direct routes via bike. All the comfortable biking options are windy such as Goose Creek Path. Taking such a circuitous route to go west takes time.
Person who drives and bikes on Iris Avenue

The city’s bike network serves diverse riders and trip purposes, providing essential connections for recreation, exercise and transportation needs such as work, medical visits or school commutes.

While parallel routes are available for choice, prioritizing Iris Avenue for improvements offers the largest safety and connectivity benefits for our community. Unlike Iris Avenue, parallel streets suffer from disjointed intersections, making navigation tricky for pedestrians and cyclists.

This map shows the parallel street routes north and south of the core study area on Iris Avenue from Broadway to 28th Street. It also shows the indirect routing areas and challenging crossing areas due to intersection offset and/or crossing streets with higher speeds/volume in the secondary study area.

Area Improvements

HOW WE ARE PRIORITIZING NEIGHBORHOOD STREETS

We’ve heard your feedback and are monitoring parallel streets

Speeding

In addition to speeding on Iris Avenue, speeding on the side streets is a concern and affects the safety and quality of life of residents and users of those streets. We’ve heard from the community that traffic diversion happens on these side streets today. Residents are concerned this will increase as a result of the Iris Avenue Transportation Improvements Project.

Routes Added

Neighbors identified some streets that experience diversion today, and staff added additional parallel vehicle routes to the list. Those street segments, along with the number and prevailing speeds of vehicles, are shown below.

Traffic Calming

Staff will identify the specific locations along these street segments to receive traffic calming. Street segments with the largest speeding problem will be prioritized first. These prioritized segments will receive speed mitigation and traffic management when the Iris project is implemented.

Monitoring

Additional street segments that will be monitored for increases in traffic and speeds are also shown.

EXAMPLES OF NEIGHBORHOOD SPEED MITIGATION AND TRAFFIC MANAGEMENT STRATEGIES

Examples of speed bump on Floral Drive and turn restrictions at Broadway and Hawthorn Avenue.

Core and Secondary Study Area speed mitigation investments

The city has invested considerably over the last two decades in neighborhood speed mitigation on streets with direct connections to Iris Avenue.

This map shows the traffic calming investments north and south of the core study area on Iris Avenue from Broadway to 28th Street including existing traffic calming devices, turn restrictions, and all-way stops, and signalized stops. It also shows candidate street segments for traffic calming along with street segments being monitored for traffic calming.

Our Alternatives Development Process

We used community feedback, data analysis, technical expertise and best practices to develop four conceptual design options.

What we heard:

Safety is the primary concern, followed by high vehicle speeds and increased traffic congestion. Community feedback supports improving safety and comfort for biking, walking and crossing Iris Avenue. There is also a request for the city to recognize Iris Avenue’s role as a key east-west driving route and consider removing the bike facility from Iris Avenue.

Infographic showing that the City hosted 34 events where many engagement activities were offered by the city to receive feedback. The City has received more than 3,100 comments so far showing that there has been a lot of community participation on the project. Safety has been the top priority and concern of participants. Most support from participants is for travel choices (biking, walking and transit) along with safe and comfortable connections. Unique feedback from participants wanted the City to consider removing bike lanes from Iris Avenue.

What the data showed:

CORRIDOR CRASH DATA

There have been a total of 345 crashes, or roughly 43 per year along the Iris Avenue corridor from 2016 through 2023, six resulting in serious injury.
143 of those were rear-end crashes.
58 of those were approach-turn crashes, turning across oncoming traffic.
Iris Avenue from 19th Street to 28th Street is on the 2023-2027 Vision Zero Action Plan High Risk Network.

This map shows how many pedestrian and bicycle crashes happened in the core study area on Iris Avenue from Broadway to 28th Street. Between 2016 and 2023, there were 22 pedestrian and bicycle crashes along the Iris Avenue corridor with 45% of those crashes happening near the 26th/Folsom Street intersection.

What the guidance said:

City staff consulted best practices, design standards and guidelines to identify all potential solutions to the issues identified by the data and community engagement to develop 13 possible design options for Iris Avenue corridor.

HOW THE DESIGN OPTIONS WERE CHOSEN

The 13 possible design options included a range of solutions that explored different bike and pedestrian facility types, multi-use paths, as well as a range of lane configurations, from two to five vehicle lanes.

The designs were chosen because they supported plans, policies, and project and city goals and addressed the issues identified through community engagement, data analysis and preliminary traffic operations analysis.

SOME OF THE PLANS, POLICIES, AND PARNERSHIPS THAT IMPACTED THIS PROJECT

Infographic showing some of the plans, policies, and partnerships that impacted this project including: Boulder Design and Construction Standards, Boulder Vision Zero Action Plan, Federal Highway Administration Safe System Approach, American Association of State Highway and Transportation Officials Policy on Geometric Design of Highways and Streets, the National Association of City Transportation Officials Urban Street Design Guide, U.S. Access Board Public Right-of-Way Accessibility Guidelines, Federal Highway Administration Manual on Uniform Traffic Control Devices for Streets and Highways, and collaborative partnership with Colorado Department of Transportation and RTD.

CONSIDERATIONS USED TO DEVELOP THE FOUR CONCEPTUAL ALTERNATIVES

Project staff consulted city partners including Boulder Fire-Rescue, Boulder Police, Parks and Recreation, Forestry, Utilities and the Office of Disaster Management for the City of Boulder and Boulder County to apply considerations for disaster response, existing public street trees, utility relocation and stormwater drainage.

Traffic Safety

What does this mean? Potential to reduce speeds and severe crashes on the corridor.

CONSIDERATIONS:

Vehicle speed moderation
Crash reduction

Transportation Operations

What does this mean? Potential to impact vehicle travel time, vehicle turning movements and emergency response.

CONSIDERATIONS:

Corridor vehicle travel time
Vehicle turning movements
Vehicular Level of Service (LOS)
Day-to-day emergency response
Disaster emergency response

Safe and Comfortable Connections

What does this mean? Potential to enhance residential, neighborhood, and business access, low-stress walk and bike connections and transit experience.

CONSIDERATIONS:

Walking comfort
Biking comfort
Opportunity for protected intersection elements
Crossing safety and comfort

Sustaining Tree Canopy

What does this mean? Potential to preserve existing street trees and maintain the current tree canopy.

CONSIDERATIONS:

Preserves existing trees

Implementation Feasibility

What does this mean? The amount of time and cost needed to design and implement the project.

CONSIDERATIONS:

Time to design and implement
Maintenance
Right-of-way property acquisition
Utility relocation and stormwater drainage
Implementation cost

Reasons why nine of the possible design options did not advance

The Four Conceptual Alternatives

Alternative A

Spot improvements to existing sidewalk.
Two 10.5-foot travel lanes (one eastbound, one westbound).
One 10-foot center turn lane.
Two 5-foot one-way protected bike lanes (one eastbound, one westbound) separated from the travel lane by 3-foot protected buffers.

Map showing the Alternative A and C protected bike lane design for the core study area on Iris Avenue from Broadway to 28th Street. — Click image to enlarge

Map showing the Alternative A cross-section with one-way protected bike lanes and no change to the roadway width.

Alternative B

Spot improvements to existing sidewalk.
Two 11-foot travel lanes (one eastbound, one westbound).
One 10-foot center turn lane.
One 10-foot two-way protected bike lane (meeting minimum design widths with 5-foot travel lane in each direction) with one 5-foot bike protected buffer between the westbound travel lane and the protected bike lane on the north side of the street.

Map showing the Alternative B and D protected bike lane design for the core study area on Iris Avenue from Broadway to 28th Street. — Click image to enlarge

Map showing the Alternative B cross-section with two-way protected bike lanes and no change to the roadway width.

Alternative C

Four travel lanes (eastbound: one 10-foot and one 11-foot travel lane, westbound: one 10-foot and one 11-foot travel lane).
Two 5-foot one-way protected bike lanes (one eastbound, one westbound) meeting minimum design widths separated from the trave lane by 3-foot protected buffers.
South side variable width buffer/planting area where feasible.
Six-foot wide sidewalk on the north and south side.

Map showing the Alternative C cross-section with one-way protected bike lanes and a widened roadway.

Alternative D

Four travel lanes (eastbound: one 10-foot and one 11-foot travel lane, westbound: one 10-foot and one 11-foot travel lane).
One 10-foot two-way protected bike lane (meeting minimum design widths with 5-foot travel lane in each direction) with 3-foot protected buffer between the westbound travel lane and the protected bike lane.
Six-foot sidewalk on the north side of the road.

Community Priorities

Community engagement is a priority. Iris Avenue users have had an opportunity to shape the future of this important street.

Since summer 2023, staff have met the community on walks, bike rides and accessible roll and strolls, at grocery stores, recreation centers and community parks, at two in-person open houses, a business luncheon and at the Boulder farmers markets.

Community priorities: How Iris Avenue users ranked the design considerations

Infographic showing the highest priority (more than 100 responses), the medium priority (between 100 and 20 responses), and the lowest priority (less than 20 responses) rankings of community participants. The highest priority design considerations were: corridor vehicle travel time, crash reduction, biking comfort, crossing and safety comfort, vehicle speed moderation, and preserving existing trees. Medium priority design considerations were: disaster emergency response, time and cost to design and implement, vehicle turning movements, walking comfort, day-to-day emergency response, transit accessibility, and opportunity for protected intersection elements. Lowest priority design considerations were: stormwater damage, right-of-way property acquisition, and utility relocation.

HOW WE SELECT A RECOMMENDED ALTERNATIVE

The city uses the CEAP* process to identify a recommended alternative by evaluating each conceptual alternative against the criteria of the three cornerstone components of this process: the CEAP Checklist, Project-Specific Evaluation Criteria and Community Input.

Infographic showing the three steps toward staff recommendation of an Alternative. The first step is the CEAP Checklist. The CEAP checklist evaluates potential social and environmental impacts of each alternative. This provides an opportunity to balance multiple community goals in the design of a capital project by assessing consistency with policies outlined in citywide and departmental plans, like the Boulder Valley Comprehensive Plan, Transportation Master Plan and Vision Zero Action Plan. The second step is project-specific evaluation criteria. Project-specific evaluation criteria provide more detailed information on each alternative to be er compare and contrast them and how they meet project and city goals. The 17 criteria evaluate for safety, safe and comfortable connections, transportation operations, implementation feasibility and whether the alternative sustains the public street tree canopy. The third step is community input. Community feedback builds on the checklist and project-specific evaluation criteria and informs the staff recommendation. Major themes included vehicle travel time, crash reductions, biking and walking safety and comfort, crossing safety and comfort, vehicle speed moderation and preserving existing trees.

What is the next step in the project process

Infographic showing the project process for the Iris Avenue Transportation Improvements project. The first step was to Establish Guiding Plans and Policies. The second step was to Understand the Corridor. The third step was to Identify Improvement Options. The fourth step was to Develop Improvement Options Screening Criteria. The fifth step was to Screen Improvement Options for Feasibility. The sixth step was to Refine Remaining Options into Conceptual Alternatives. The seventh step was to Present Four Feasible Conceptual Alternatives for Feedback. The eighth step is CEAP Alternatives Evaluation. The current and ninth step is to Present CEAP Alternatives Evaluation and Staff Recommendation for Feedback. The tenth step will be Finalize CEAP Alternatives Evaluation and Staff Recommendation. The final and eleventh step will be to Present CEAP Alternatives Evaluation and Staff Recommendation for Board and Council.

*The Community and Environmental Assessment Process (CEAP) is a formal review process that assesses the potential impacts of capital improvement projects to help select the best alternative.

EVALUATION RESULTS

Chart showing the results of the four conceptual alternatives evaluation weighing design considerations and CEAP checklist criteria.

Recommended Alternative

ALTERNATIVE B provides the most safety benefits with lower costs and time to implement

Each alternative has trade-offs and competing priorities. Alternative B best balances community priorities, advances city policies and implements federally recommended safety improvements.

Alternative B Benefits

Reconfigures vehicle lanes (between 13th Street and Folsom/26th Street) to achieve the most safety benefits like moderating vehicle speeds and reducing crashes and crash severity with minimal added travel time.
Doesn’t widen the roadway, costing less and taking less time to implement.
The center turn lane reduces common vehicle crash types, supports vehicles turning in and out of side streets and driveways, and provides dedicated space for day-to-day emergency response.
The two-way protected bike facility supports all ages and abilities riding, disaster emergency response, and year-round maintenance.
Preserves the existing public street trees.
Protected intersections provide safer crossings and implements the recommendation for reducing Vision Zero Action Plan common crash types: right-turn crashes and pedestrians/bicyclists crossing the street.
Signal changes to separate turning vehicles from people walking and biking at major intersections, which has greater safety benefits for people biking, and smaller vehicle travel time impacts than a one-way protected bike lane.

CONCURRENT EFFORTS

A concurrent effort includes side street traffic calming and management in prioritized locations.

These benefits respond to the highest community priorities for crash reduction, moderating vehicle speeds, providing bike and pedestrian comfort and preserving trees with minimal added travel time.

This map shows the core study area on Iris Avenue from Broadway to 28th Street. Between Broadway and 13th Street, it also shows the Broadway Bookend Improvements area, and between 28th Street and Folsom/26th Street is the 28th Street Bookend Improvements area. The Recommended Alternative Improvements area is between 13th Street and Folsom/26th Street.

Alternative B Conceptual Design Tour

Conceptual Design Notes

Vertical separation material for the protected bike lanes and raised transit boarding island details to be determined in next phase of design based on detailed floodplain analysis.
Emergency Access to two-way protected bike lane to be determined in next phase of design.
Spot improvements will be made to existing sidewalks to improve accessibility and side street crossings.
Temporary Construction Easements to be determined in next phase of design.

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Broadway Bookend

A) Two-way protected bike lane continues to intersection and connects across Broadway to path to Foothill Elementary and Newlands neighborhood. The vehicle lane configuration does not change.

B) Shared Bus Stop accommodates protected bike lane.

C) Improvements to Boulder County Campus driveways and multi-use path gap to be determined in next phase of design.

15th Street Crossing

A) Modified median refuge island to provide separate crossings for people walking and biking.

B) To 13th Street GreenStreet and Downtown.

C) Details to manage conflicts between turning vehicles and people biking at unsignalized intersections to be determined in next phase of design.

19th Street Protected Intersection

A) Transit boarding island eliminates conflicts between buses and people biking and shortens the distance to cross Iris Avenue by approximately 20'.

B) Protected Intersection corner islands physically separate people walking, biking, and rolling from vehicles up to and through the intersection and make it easier for these travelers to see and be seen by drivers. Signals changes will separate vehicle and bike movements.

C) Dedicated right-turn lanes separate turning vehicles from vehicles traveling through the intersection. The number of westbound and eastbound lanes on approach to intersection remains unchanged in Alternative B.

Hermosa Drive Crossing

A) Bike ramp and path extension allow people biking to more easily transition between Hermosa Drive and the signalized crossing of Iris Avenue.

B) Additional crossing enhancements to be determined in next phase of design.

C) Northside two-way protected bike lane allows for easy connections to the path to Kalmia Avenue.

Folsom/26th Street Protected Intersection

A) Transit boarding island eliminates conflicts between buses and people biking and shortens the distance to cross Iris Avenue by approximately 20'.

B) The number of eastbound lanes on approach to Folsom/26th Street remains unchanged in Alternative B.

C) An eastbound bike lane is maintained along with the existing south side multi-use path to provide direct connections along the south side of Iris Avenue.

28th Street Bookend

A) The northside two-way protected bike lane transitions to sidewalk-level at Elmer’s Twomile Creek and continues to 28th Street. Separate projects are planned to improve connections to the Wonderland Creek Greenway and the future Diagonal Bikeway. The sidewalk will also be improved adjacent to the bike lane.

B) A southside sidewalk-level two-way protected bike lane begins at the connection to the Elmer’s Twomile Creek Path and continues to 28th Street. The sidewalk will also be improved adjacent to the bike lane.

C) The westbound left-turn to Safeway will be prohibited due to a recurring crash pattern. All commercial driveways will be reconstructed to current standards.

TRAFFIC SAFETY

Alternative B moderates vehicle speeds and reduces the number and severity of crashes.

Redesigning the road addresses the common crash types on Iris (rear-end, left-turn and right-angle crashes) and responds to community priorities for crash and vehicle speed reduction.

Community priorities

The community told us high vehicle speeds cause excessive street noise and feelings of insecurity for people traveling across all modes.
When considering the alternatives for Iris Avenue, crash and vehicle speed reduction are two of the community’s highest priorities.

In the last 10 years my family has been involved in two accidents on Iris Avenue. My mother-in-law was in a vehicle accident that totaled her car and left her with a broken arm. This occurred on Iris Avenue where another driver trying to turn left onto Iris Avenue through multiple lanes pulled out in front of her colliding with her. I have personally had several near-misses on my bicycle navigating Iris Avenue daily but was struck once by a vehicle turning onto Iris Avenue at 19th street.
Boulder resident

Even though Iris Avenue serves as a major connection between Diagonal and Broadway, it should not be a speedway. I would like to see the speed limit kept low for the safety of all. Everything is easier and safer if people drive slowly.
Boulder resident

Plan, policy or data guidance

The Vision Zero Action Plan identified crashes involving people speeding as an area of concern.
Though the posted speed limit on Iris is 35 mph, most people are driving over the speed limit – at 40 and 45 mph or more.
Speed increases the risk of serious injury or death: a pedestrian has 47% chance of dying on Iris when hit by a vehicle driving these speeds.

Federal Highway Administration guidance

A roadway reconfiguration, converting an existing four-lane roadway to a three-lane roadway with a center two-way left-turn lane, can improve safety, calm traffic, provide better mobility and access for all road users, and enhance overall quality of life.

How the design considerations were evaluated

Vehicle speed moderation

Reduction in prevailing speed and/or speeding by reducing the number of lanes and providing vertical/visual friction (trees, bike lane separation).

What the evaluation showed Vehicle lane repurposing can reduce prevailing speeds by up to 5mph and vertical friction from bike lane separation can reduce prevailing speeds up to 2mph. Alternative B potential speed moderation of up to 7 mph.

Crash reduction

Reduction in the number and severity of crashes by: reduced number of conflict points; addition of turn lanes; separation of vulnerable road users; reduced speeds (based on vehicle speed moderation criteria); motorist-bicyclist interaction and expectation.

What the evaluation showed Lane repurposing from four lanes to three lanes can reduce vehicle crashes by 25% to 50%. Implementing a protected bike lane can reduce vehicle-bike crashes by 35%. Alternative B reduces both vehicle crashes and vehicle-bike crashes.

CEAP Checklist: Need for additional transportation improvements

Assesses for transportation improvements.

What the evaluation showed Alternative B has a positive effect on transportation because it provides greater separation for people walking from vehicle travel, a two-way protected bike lane, and opportunities for safer crossings.

VEHICLE SPEED MODERATION

Left: Map showing the Iris Avenue existing conditions cross-section with four vehicle lanes and conventional bike lanes two-way protected bike lanes between 13th Street and Folsom/26th Street. Right: Map showing the Alternative B Recommended Alternative cross-section with two-way protected bike lanes and no change to the roadway width between 13th Street and Folsom/26th Street.

MAIN CRASH TYPES

The main crash types on Iris Avenue are rear end and turn-related. Alternative B would reduce both vehicle crashes and vehicle-bike crashes.

THREE VEHICLE LANE ROAD CONFIGURATIONS

Three vehicle lane road configurations can reduce the number of conflict points and the severity of crashes when they do occur. The number of typical crash types are reduced by 50% when a road reconfiguration, from four lanes to three, is introduced.

TRANSPORTATION OPERATIONS

Alternative B prioritizes important safety improvements with minimal change to travel time.

Maintenance of lane configuration at bookends preserves travel time reliability for all users. In general, travel time increases of around 40-60 seconds or less are mostly imperceptible changes a driver wouldn’t feel over time.

Community priorities

The community told us Iris Avenue is an important east-west vehicle route in north Boulder.
When considering the alternatives for Iris Avenue. Vehicle travel time along the corridor is a high community priority.

Because this is one of only a few continuous east-west vehicular travel routes in this part of the city, I prioritize commuting travel time via vehicles and bikes.
North Boulder resident

I place almost zero priority on travel times by car, even though I’ve only driven Iris and haven’t biked on it. It’s a high priority to me to place people above vehicles. We can never win by trying to improve car travel times. Only reducing traffic will help.
Boulder resident

Plan, policy or data guidance

End-to-end travel time was considered. End-to-end travel times are measured from the center of the intersection and include any time spent waiting in queued traffic on a red signal at the corridor ‘bookend’ intersections at Broadway and 28th Street. Times reflect the morning and evening peak travel periods. Travel time varies by direction, time of day, speed limit compliance, and seasonal variability such as school being in session.
Today, the average end-to-end travel time is between 3 and 4 minutes and the slowest trips can take between 4 and 5 minutes.

How the design considerations were evaluated

Corridor vehicle travel time

Traffic modeling identified the potential travel time change for the average trip, for most trips (the 95th percentile or the travel time 95% of drivers experience), and the slowest trips (5% or less of all vehicle trips) to drive Iris from end-to-end.

What the evaluation showed Traffic modeling shows the travel time for the average trip increased by up to 46 seconds, most trips increase by up to 58 seconds, and the slowest trips increase by up to 2 minutes 09 seconds.

WHAT TRAVELERS EXPERIENCE ...

Chart showing how high travel delays over a year of time is what travelers remember. People driving tend to remember outlier moments even if they happen less than 5% of the time, and only during certain days of the week or times of the year. The chart is for illustration purposes only. Travel times typically vary by direction, time of day, and speed limit compliance.

EXISTING CONDITIONS AND ALTERNATIVE B AM AND PM TRAVEL TIME DATA COMPARISON

Chart showing the combined AM and PM peak travel times in percentage of trips and corridor travel time in minutes and seconds between Alternative B and the Existing Conditions along the Iris Avenue corridor. The existing average travel time is 3 minutes and 25 seconds. The existing 95th percentile travel time is 4 minutes and 21 seconds. The maximum existing travel time is 5 minutes and 17 seconds. Existing times are based on traffic model and differ slightly from observed times.

IRIS AVENUE TRAVEL TIME INCREASE

Chart showing the combined AM and PM peak increase in travel times for each Alternative along the Iris Avenue corridor. For Alternative A average trips would increase by 1 minute and 3 seconds, most trips (95th percentile) would increase by 1 minute 4 seconds, and the slowest (maximum) trips would increase by 1 minute and 42 seconds. For Alternative B, the recommended alternative, average trips would increase by 46 seconds, most trips (95th percentile) would increase by 58 seconds, and the slowest (maximum) trips would increase by 2 minutes and 9 seconds. For Alternative C average trips would increase by 17 seconds, most trips (95th percentile) would increase by 27 seconds, and the slowest (maximum) trips would increase by 1 minute and 8 seconds. For Alternative D average trips would increase by 25 seconds, most trips (95th percentile) would increase by 36 seconds, and the slowest (maximum) trips would increase by 1 minute and 10 seconds. — Combined modeled AM and PM peak travel times

Alternative B provides dedicated space for turning vehicles and emergency response.

Center turn lanes enhance safety and traffic flow by creating a dedicated space for left turns, reducing conflicts with oncoming or passing traffic. This space, along with the two-way protected bike lanes during a disaster, can be utilized by emergency vehicles to respond to emergencies.

Community priorities

The community told us safer neighborhood and business access is essential, maintaining vehicle travel is important, and they wanted to preserve emergency response.
When considering the alternatives for Iris Avenue, vehicle travel time is a high priority, and vehicle turning movements and emergency response are medium priorities.

Turning out of my neighborhood is kind of difficult, especially during higher traffic times.
North Boulder resident

I would like to see maximum throughput for vehicles preserved for fast moving wildfire scenarios. Parents would potentially need to drive to fetch their children or other family members and then escape in the case of a fast-moving wildfire. Iris is currently the only corridor potentially capable of handling that scenario. To reduce the number of lanes would be irresponsible given the everincreasing likelihood of wildfires in the hills above this area of the city.
Boulder resident

Plan, policy or data guidance

The Vision Zero Action Plan identified common crash types that occur on the High Risk Network: left turn crashes, right turn crashes, right on red crashes, and pedestrian crashes while crossing the street. The High Risk Network is 7% of city streets that have roughly five times more risk than all of Boulder’s arterials combined. Iris Avenue is on the High Risk Network.

Federal Highway Administration guidance

Roadway reconfiguration with lane repurposing opens a more predictable and practical path for emergency responders.

How the design considerations were evaluated

Vehicle turning movements

Access to properties via dedicated turn lanes rather than through travel lanes provide safety and operational improvements by separating through and turning movements.

What the evaluation showed The center turn lane provides space for all turning movements on and off of Iris Avenue, which helps traffic flow and reduces crashes by removing turning vehicles from through lanes.

Vehicular Level of Service

Traffic modeling to identify how many eastbound and westbound vehicles can travel Iris Avenue from end to end during a given time period.

What the evaluation showed Signal changes to separate vehicle and bike movements at intersections, in accordance with industry best practices for protected bike lanes, may increase driver delay at intersections. These changes provide acceptable levels of vehicle level of service.

Day-to-day emergency response

Provides space for emergency response vehicles to move through traffic.

What the evaluation showed The center turn lane provides dedicated space for day-to-day emergency operations.

Disaster emergency response

Provides four lanes with the same amount of space for private vehicles to evacuate during a disaster and for disaster emergency response vehicles to have dedicated space to move through traffic.

What the evaluation showed The two-way protected bike lane is wide enough to accommodate emergency vehicles and would serve as an emergency priority lane during a disaster.

CEAP Checklist: Need for additional police and fire services

Increased need for police and fire services.

What the evaluation showed The center turn lane and two-way protected bike lane in Alternative B have positive effects on police and fire services by providing dedicated space for emergency operations for both day-today and disaster emergency response scenarios. Roadway reconfiguration will improve safety, reducing the need for emergency response.

Map showing the Alternative B vehicle lane design for the core study area on Iris Avenue from Broadway to 28th Street. Design includes Broadway Bookend Improvements, Existing Median Refuge, Center Turn Lane, 19th Street Dedicated Right Turn Lanes, Second Eastbound Lane Added at Folsom Street, 26th Street Dedicated Right Turn Lane, and the 28th Street Bookend Improvements.

Typical 4 lane street (left); Typical 3 lane street (right)

Infographic showing in day-to-day scenarios, the Boulder-Fire Rescue and Police departments can utilize the center turn lane for emergency operations.

DAY-TO-DAY EMERGENCY RESPONSE

In day-to-day scenarios, the Boulder-Fire Rescue and Police departments can utilize the center turn lane for emergency operations.

Infographic showing that roadway design features for the use of the center turn lane as a second eastbound evacuation lane are being coordinated with ODM, BPD, and BFR. In a disaster scenario, the two-way protected bike lane in Alternative B is wide enough to accommodate emergency vehicles.

DISASTER EMERGENCY RESPONSE

In a disaster scenario, the two-way protected bike lane in Alternative B is wide enough to accommodate emergency vehicles.

SAFE AND COMFORTABLE CONNECTIONS

Alternative B provides safer and more comfortable walking and biking facilities and provides more space for protected intersection elements because it repurposes a vehicle travel lane.

One-way and two-way protected bike lanes (PBLs) provide similar safety benefits, but there are applications where one better meets the needs of a corridor. A two-way PBL is the best alternative for Iris Avenue due to community input, citywide goals and best practices. Below are our findings that show why the two-way protected bike lanes will be safe, comfortable and intuitive for people biking along and across Iris Avenue.

The north side of Iris Avenue has fewer conflict points between bikes and vehicles and provides the best connections to the bookends.
The extra width of a two-way PBL and adjacent five-foot buffer makes it the most accessible bike facility. It allows people biking to ride side-byside, farther from traffic, and pass safely, which is especially important with the growing use of e-bikes.
The two-way PBL is beneficial for disaster emergency response because it is wide enough for emergency vehicles to use in the event of an evacuation.
The north side two-way alignment is easier and more cost-effective for the city to maintain. Standard snowplows and street sweepers can service it, unlike narrower one-way PBLs requiring specialized equipment. Northern sunlight exposure also helps snow melt faster in winter.
To reduce potential conflicts with turning vehicles who need to look for people biking in both directions, the project will implement signal changes that separate vehicle and bike movements, install protected intersection elements and add two-way signs and markings along Iris Avenue.

Community priorities

The community told us they want connectivity and safety for walking, rolling, biking and taking transit, and to be able to cross Iris Avenue safely and conveniently.
When considering the alternatives for Iris Avenue, biking comfort, pedestrian crossing safety and comfort, and bike crossing safety and comfort are high priorities and walking comfort and transit accessibility are medium priorities.

This arterial is vital to become a transit and multimodal city. But for users to use this corridor it must feel safe for all roadway users. Speeds should be reduced, and protection should be put in place for bicycles and pedestrians and safe transit accessibility for the less mobile.
Palo Park commuter

Crossing Iris has been unsafe for years, cars are going very fast, and very often do not yield to bikes/peds even at the designated crossing locations.
Boulder resident

Plan, policy or data guidance

The Vision Zero Action Plan identifies specific actions and strategies to reduce the most common crash types, including right-turn crashes and pedestrians/bicyclists crossing the street.

Federal Highway Administration guidance

Roadway reconfiguration with lane repurposing improves crossing safety for people walking and biking by providing space for pedestrian refuge islands, bicycle lanes or transit stops and reducing the number of vehicle lanes they have to cross.

How the design considerations were evaluated

Walking comfort

Provide a pedestrian route that addresses the City of Boulder Low Stress Walk and Bike Network Plan pedestrian stress factors.

What the evaluation showed Alternative B addresses the Low Stress Walk and Bike Network Plan pedestrian stress factor of separating people walking from vehicles. The north side two-way protected bike lane provides greater separation for people walking from vehicle travel. The attached sidewalk on the south side does not provide a buffer between pedestrians and vehicle traffic for about 37% of the corridor.

Biking comfort

Provide a bike route that implements the City of Boulder Low Stress Walk and Bike Network Plan recommendation.

What the evaluation showed The north side twoway protected bike lane implements the Low Stress Walk and Bike Network Plan recommendation, allows people biking to move in both directions, allows for passing and side-by-side riding, and is located on the north side of the street where there are fewer conflicts with turning vehicles at side streets and driveways.

Opportunity for protected intersection elements

Evaluate the extent to which protected intersection elements can be incorporated into signalized and unsignalized intersections.

What the evaluation showed Alternative B repurposes a vehicle travel lane which provides space for protected intersection elements at intersections.

Crossing safety and comfort

Evaluates how well space for safer roadway crossings, like pedestrian refuge islands, can be provided.

What the evaluation showed Alternative B repurposes a vehicle lane and includes a center turn lane and so provides opportunity for pedestrian refuge islands.

CEAP Checklist: Effects on special populations

Assesses the effects the project may have on or would benefit special populations.

What the evaluation showed The sidewalks, ADA curb ramp improvements, shorter crossings, and protected intersection elements of Alternative B have positive effects on people living with disabilities, older adults, and children and youth.

HOW ALTERNATIVE B PROVIDES SAFE AND COMFORTABLE CONNECTIONS

Photos showing examples of an End-to-End Two-Way Protected Bike Lane, Center Turn Lanes, Protected Intersections, Transit Stop Enhancements, and Safer Pedestrian Crossings.

ALTERNATIVE B INTERSECTION AND DRIVEWAY ACCESS ALONG IRIS AVENUE

Map showing the Alternative B intersection and driveway access for the core study area on Iris Avenue from Broadway to 28th Street. There are 13 total north-side conflicts with five being unsignalized intersections or commercial driveways and 8 that are residential or low-volume driveways. There 34 total south side conflicts with 10 being unsignalized intersections or commercial driveways and 24 that are residential or low-volume driveways.

SUSTAINING TREE CANOPY

Alternative B preserves 92% of the existing public street trees.

Alternative B maintains the current tree canopy coverage of Iris Avenue by removing only 10- 12 of our 150 public street trees.

Community priorities

The community told us they want placemaking and attractive facilities – and public street trees are key to these goals.
When considering the alternatives for Iris Avenue, preserving the tree canopy is a high priority.

I am a believer that trees, safe bikeways, and safe walkways are the most effective ways to make an enjoyable experience while commuting. It’s been seen across the world in many cities. Cars should not take ultimate priority. End of story.
Boulder resident

Trees are of utmost importance. If shade trees are preserved and new ones planted, then Iris will become much cooler and friendlier for peds and bikes, and more of them will use it as a main corridor for travel.
Boulder resident

Plan, policy or data guidance

The City of Boulder Urban Forestry Strategic Plan and Boulder Valley Comprehensive Plan (BVCP) recognize the importance of the urban canopy, street trees and streetscapes, and the importance of the urban forest. The citywide overall canopy cover is 16%.
There are 150 public street trees along the Iris Avenue project area. These trees provide the project area with 25% canopy cover.

How the design considerations were evaluated

Preserving existing trees

Measures the number of public street trees to be removed.

What the evaluation showed Alternative B does not require roadway widening and so only removes trees to improve sightlines or provide clear space around existing or new sidewalks and bike lanes. Alternative B will remove 10-12 trees of the existing 150 trees to improve, or about 8% of total tree canopy on Iris Avenue.

CEAP Checklist: Impact to natural areas or features

Measures the potential for disturbance to or loss of significant species, plant communities, wildlife habitats, or ecosystems, and specifically, the disturbance to or loss of mature trees or significant plants.

What the evaluation showed Alternative B has minimal impacts to existing public street trees: 10 to 12 trees will need to be removed for sidewalk improvements and sightlines, or about 8% of the urban forest on Iris Avenue.

CEAP Checklist: Impact to water quality

Measures the potential impacts to water quality from construction activities, changes in the amount of hardscape, storm drainage, vegetation or pedestrian and vehicle traffic.

What the evaluation showed Alternative B does not require roadway widening and so does not require clearing, create an increase in hardscape, or make changes to site ground features, storm drainage or vegetation.

CEAP Checklist: Impact to air quality

Measures the potential shortand long-term impacts to air quality from mobile sources, like vehicle trips, and stationary sources.

What the evaluation showed Alternative B has no effect on air quality because the positive effects from retaining 92% of the existing public street trees and from providing safer non-vehicle travel options are offset by the potential for more emissions from increased vehicle travel time.

CEAP Checklist: Disturbance of riparian areas

Disturbance to a riparian corridor.

What the evaluation showed Alternative B does not encroach on the Twomile canyon creek on the northeast corner of Broadway and Iris Avenue.

CEAP Checklist: Impact to geology and soils

Change in soil or fill material on the site.

What the evaluation showed Alternative B can be implemented within the existing roadway width and so make no changes to soil or fill materials.

CEAP Checklist: Exposure to excessive noise

Potential exposure to excessive noise.

What the evaluation showed Alternative B can be implemented within the existing roadway width and requires few public street tree removals and so does not expose adjacent properties to excessive noise.

ALTERNATIVE B CAN BE IMPLEMENTED WITHOUT WIDENING THE ROADWAY, PRESERVING EXISTING TREE CANOPY

Example area where existing trees are preserved due to the roadway reconfiguration of Alternative B.

Map showing an example area along the Iris Avenue corridor where existing trees are preserved due to the roadway reconfiguration of Alternative B.

EXISTING TREES ALONG THE IRIS AVENUE PROJECT CORRIDOR

IMPLEMENTATION FEASIBILITY

Alternative B provides safety benefits without widening the roadway and is more easily implemented.

Recently completed projects, like Baseline Road, provide early estimates for how much Alternative B could cost – around $5 million –because it can be built within the existing roadway with other minimal impacts. The recently completed 30th Street multimodal projects from Arapahoe to Aurora Avenues have similar impacts to Alternatives C and D and could cost approximately 3-4 times more.

Community priorities

The community told us they want road conditions and maintenance to improve.
When considering the alternatives for Iris Avenue, time and cost to design and implement is a medium priority.
Utility relocations, impacts to stormwater drainage and right-ofway easements from nearby property owners are low priorities.

I’ve ticked ‘time and cost to design and implement’ because this project has already been in the air for a decade by some measures, and I’d selfishly like to see it completed in my lifetime. Or maybe even in time for my children to have safe options for independent travel around town as they get older.
Boulder resident

The three lane options are much nicer than the four lane options. People would still speed a lot with four lanes. It is essential that the bike lanes have good snow removal. A major problem with the current bikeway north of Iris is that it is not plowed and remains snowy and icy long after a storm.
Boulder resident

Plan, policy or data guidance

The Boulder Valley Comprehensive Plan prioritizes investments for the safe travel of people using all modes to ensure the safe and efficient use of existing travel corridors.

How the design considerations were evaluated

Design and implementation

Evaluates for the time and effort needed to implement the project, considering factors that could complicate implementation, like necessary permits.

What the evaluation showed Alternative B does not require roadway widening and so takes less time to implement.

Maintenance

Assesses added maintenance requirements for transportation infrastructure, snow and ice response, and street sweeping based on discussions with the maintenance division.

What the evaluation showed The two-way protected bike lane in Alternative B is easier to maintain, provides more space for snow storage and can better gain benefits of sun exposure in winter months due to its northside alignment to melt and evaporate snow and ice, supporting snow and ice response.

Right-of-way property acquisition

Analyzes the number and size of permanent and temporary construction easements required, based on alternative maps, rightof- way survey, and field walk data.

What the evaluation showed Alternative B does not require permanent right-ofway easements and requires one to five temporary construction easements.

Utility relocation and stormwater drainage

Quantitative counts of impacted ground-level utility features and drainage impacts, including inlets, manholes, and pipe lengths, based on alternative design, existing storm drainage data, GIS analysis, and field walk observations.

What the evaluation showed Alternative B impacts 8 stormwater inlets and requires 21 utility poles to be relocated, which are less than half the impacts from four lane alternatives.

Implementation cost

Order of magnitude engineering cost estimates for construction.

What the evaluation showed Alternative B does not require roadway widening and so costs approximately $5 million to implement, which is three to four times less than four lane alternatives.

CEAP Checklist: Economic vitality: Utilization of existing infrastructure

Evaluates the use of existing infrastructure, effects on operating expenses, effects on economic activity, and impacts to businesses, employment, retail sales or city revenue.

What the evaluation showed Alternative B can be implemented within the existing curb-to-curb width and so has no effect on existing infrastructure or operating expenses. Alternative B maintains current vehicle access and improves the safety and connectivity to the shopping centers between Folsom/26th Street and 28th Street and so has no effect on economic activity, and impacts to businesses, employment, retail sales and city revenue.

ROADWAY AREAS AVAILABLE FOR RECONSTRUCTION AND RECONFIGURATION

Infographic showing the existing conditions on Iris Avenue between 13th Street and Folsom/26th Street. The 50-foot existing roadway between the curbs would be available for street reconstruction. While the sidewalks and existing right-of-way where there are trees would be available for reconstruction. Alternative B minimizes impacts to utilities, ROW, and trees by repurposing one lane within the existing roadway width.

MAINTAINING PROTECTED BIKE LANES

Baseline Road protected bike lane (left); Specialized plow for protected bike lanes (right).

PROTECTED INTERSECTIONS

Alternative B reduces common crash types and the severity of crashes when they do occur at intersections by providing space for protected intersections.

From 2016 to 2023, there were 345 vehicle crashes on Iris Avenue. Among these, 22 involved pedestrians (4) and bicyclist (18). The intersection at Folsom/26th Street accounted for 45% of these crashes. In all cases involving pedestrians or bicyclist, the driver was at fault for not yielding at intersections or driveways.

Community priorities

I walk my kids to daycare at 26th and Iris every day. That intersection is very dangerous.
Boulder resident

Plan, policy or data guidance

Evidence from National Association of City Transportation Officials guidance found increases in drivers yielding to people walking and biking following protected intersection installation.

What the evaluation showed

The roadway reconfiguration proposed in Alternative B creates space for the highest quality safety improvements such as protected intersections, including at Folsom/26th Street.

It will reduce the Vision Zero Action Plan common crash types that occur on the High Risk Network (right turn crashes and pedestrians/bicyclists crossing the street). It will also reduce the severity of crashes when they do occur by moderating vehicle speeds.

Pedestrian and bicycle crash data on Iris Avenue

ALTERNATIVE B FOLSOM/26TH STREET INTERSECTION CONCEPT

This rendering shows how Alternative B at Folsom/26th Street intersection might look. Diagram is for illustrative purposes only and highlights the transition from three lanes to four lanes at the Folsom/26th Street intersection in the eastbound direction.

CONVENTIONAL INTERSECTION

Infographic showing how a wide radius allows fast turns which make looking for people walking and biking harder.

PROTECTED INTERSECTION

Infographic showing how adding corner islands, tightening intersections, slow turning vehicles therefore making crossings safer.

BOOKEND IMPROVEMENTS

The bookends have thoughtful design considerations that balance the community priorities of improving safety for all while keeping everyone moving.

Traffic modeling and analysis determined the bookends of Iris Avenue are key to moving people and providing travel time reliability for all who travel the corridor.

BOOKENDS BENEFITS

Infographic highlighting the overall bookend benefits which include maintaining the current vehicle lane configuration to preserve travel time reliability for all who travel along the corridor. The two-way protected bike lanes continue from end to end. Existing crossings and connections to key destinations will be optimized and access management at commercial driveways will reduce recurring crashes.

Infographic highlighting an overview of the Broadway Bookend Improvements with no changes to existing vehicle lane configuration between Broadway and 13th Street. Transit stops will be upgraded to shared stops to provide a larger boarding area and accommodate the protected bike lanes. Bike lanes and sidewalks will be separated from each other and from vehicle lanes to and through the intersection. Improved crossings of Broadway will provide a direct connection to the path that continues west to Foothill Elementary and the Newlands neighborhood. Traffic signals will be optimized and dedicated bike and pedestrian signal phases maintained. Infographic highlighting an overview of the Broadway Bookend Improvements with no changes to existing vehicle lane configuration between 28th Street and Folsom/26th Street. The protected bike lanes east of Elmer’s Two Mile Path are two-way sidewalk-level facilities on both sides of the street to provide direct connections to shopping centers, transit stops, 28th Street paths and routes east to the Wonderland Creek Greenway and the planned Diagonal Bikeway. Commercial driveways will be reconstructed to meet current standards and will include two-way signs and markings. The westbound left into the Safeway parking lot will be prohibited due to recurring left-turn crashes.

Our Next Steps

Where are we at in the process?

What is the next step in the decision process?

What’s next after the CEAP is finalized?

The final CEAP and recommended alternative will be brought to TAB.

TAB will make a recommendation to the City Council on the CEAP and recommended alternative.

The City Council will receive the CEAP and TAB’s recommendation and be asked to take action.

If the City Council approves the recommended alternative, final design and implementation will follow as funding is secured.

Open House Assistance

The City of Boulder is in the process of making all of its websites and applications more accessible. While much progress has been made, some features and actions in this virtual open house may be inaccessible for certain people. If you would like assistance using and navigating this map, click the following link to contact the City's ADA Coordinator for assistance: Accessibility Complaint or Request Form . You may also call the City's ADA Coordinator at 720-576-2506. Please know that the City is happy to assist you and do not hesitate to reach out.

Questionnaire

Thank you for reviewing the virtual open house for the Iris Avenue Transportation Improvements project. Please complete the questionnaire below to provide feedback. If the questions don't load or you have trouble submitting, view the questionnaire on a separate page.

Iris Avenue Summer 2024 Questionnaire