Traffic Calming

Throughout the year, city staff review resident concerns alongside speed, volume, and crash data through the Neighborhood Traffic Calming Program. Locations that meet the program's eligibility requirements are scored and prioritized, so that limited resources are allocated to the locations with the greatest safety need.

As resources allow, staff aim to move forward an annual package of traffic calming projects for the top priority locations from Phase 1. The package of projects is designed and installed using modular, lower cost materials such as rubber temporary curb, delineators, and paint. Testing a design this way allows staff to evaluate a treatment on the street and adjust it if needed, before committing to the cost of permanent construction. While in this phase, a project is often referred to as a "Pilot." 

After the package of traffic calming projects is installed, staff collect data on vehicle speeds and traffic volume, typically starting at least three months after the project is in place. Projects generally remain in Pilot status for at least 12 months, giving travel patterns time to stabilize and allowing staff enough data to draw meaningful conclusions. Staff also gather public feedback on how the project functions day to day, including access concerns, visibility, and emergency response. 

A summary of evaluation results and decisions will be published on this webpage to maintain transparency and accountability.

Using the evaluation data collected in Phase 3, staff determine whether the current treatment and design is meeting its intended project goals. If the treatments installed do not yet meet the desired goals, a project is moved back to Phase 2 to allow staff to adjust the design, such as the placement or spacing of materials. Once revisions are in place, the project moves forward again in the process to Phase 3 and is re-evaluated. Once staff determine the project meets its goals, it moves to Long Term status and remains in place using its current materials. 

Traffic calming projects that meet their intended goals and prove to be effective are flagged as candidates for concrete construction. Whether and when that happens depends on several key considerations:

• Right of way available for the improvement
• Project construction costs
• City staff resources needed to manage and deliver a project
• Staff and budget available for ongoing operations, maintenance, education, and outreach
• Key partnerships and coordination with other agencies

Projects that have been evaluated and shown to be effective are prioritized for concrete construction based on these considerations, along with how well a project can be incorporated into existing and future capital investment projects. Aligning permanent construction with other planned work in the area helps staff coordinate planning and construction efforts and make good use of public resources. 

Traffic Calming Terms

Vertical Protection 

• Delineator: A flexible, plastic post that is between 2 to 4ft tall and bolted into the roadway or on top of a temporary curb to provide a clear visual signal to drivers that a space is not meant for vehicles. Also called flex post or plastic bollard. 
• Temporary Curb: A durable, plastic curb that is raised on both sides and is bolted to the road. These are typically installed with delineators on top of them. 

Slow Speeds

• Bulb-out: Delineators and temporary curb are used to extend the corner of the curb at an intersection out into the street and shorten the crossing distance for pedestrians while reducing vehicle turning speeds. 
• Chicane: A combination of two or more alternating bulb-outs placed mid-block to slow vehicle speeds by narrowing and realigning the roadway. 
• Pinch-point: Delineators and temporary curb are used mid-block to extend the curb space and narrow the roadway to slow down vehicle traffic and provide a safer crossing on low-volume streets. 

Safe Pedestrian Crossings 

• Advanced pedestrian signs: Traffic signs are placed before crosswalks or pedestrian areas like school zones to alert drivers to the presence of pedestrians and encourage them to slow down and yield. 
• In-street crossing signs: Pedestrian traffic signs that are placed within the roadway at a crosswalk to increase driver awareness and visibility of pedestrians, often helping to slow traffic through crosswalks. 

Additional Strategies 

• Daylighting: Delineators and temporary curb are used to restrict drivers from parking at intersections and adjacent to crosswalks to provide visibility for crossing pedestrians.
• Short-term striping: Low-cost paint is used that fades in about 9 to 12 months. 

Other Terms

Street Types

• As defined in the 2019 Transportation Master Plan, street types factor in the typical functional classification system while also accounting for the surrounding land use intensity and character which affect the street’s operation and design.
• See Transportation Master Plan(PDF, 14MB), page 40 and page 125, for more details

Average Daily Traffic (ADT)

• Average daily traffic (ADT) is the number of vehicles that pass a given point on a road during a specific time period.
• The City collected ADT through various methods including tube counters, radar counters, and in-person observations.

85th Percentile Speed

• The speed at or below which 85% of drivers travel on a road.
• The 85th percentile speed is typically taken from speed data collected during a 24-hour weekday period.

Serious Injury and Fatal Crashes

• A fatal injury is any injury that results in death within 30 days of the reported crash.
• A serious injury is any injury other than a fatal injury which prevent the injured person from walking, driving, or normally continuing the activities they were capable of performing before the crash occurred.

Why was my street chosen for one of these projects?

• The City selects locations for traffic calming projects based on a combination of factors, including the following:
  • Speed and Traffic Data - Streets with high vehicle speeds or traffic volumes may be prioritized to improve safety.
    Planned Roadway Improvements - Locations scheduled for repaving or restriping provide an opportunity to test safety enhancements efficiently.
  • Crash History- Areas with a history of crashes, particularly those involving people walking and biking, may be chosen for safety interventions.
  • Roadway and Land Use Context - Factors such as street width, number of lanes, nearby schools, parks, or businesses influence project selection.
  • Community Feedback - Input from residents and stakeholders helps identify areas where safety concerns exist.

How long will construction last?

• Because the City uses low-cost, modular materials for these projects, construction is typically completed within a few days. Larger projects, such as those spanning an entire corridor, may take multiple weeks. However, timelines can vary depending on weather conditions. The City's goal is to minimize disruption while making safety improvements as efficiently as possible.

Why does the City use plastic and rubber materials instead of concrete for these treatments?

• The materials the city uses for most traffic calming projects are quick to install and moveable if we need to make revisions to the project design, all at a much lower cost than using concrete. These materials can be installed by City staff in a matter of days, as well as temporarily removed, if necessary, due to emergencies, heavy snow, or other conditions. Just like a seamstress would use a lower cost fabric to test how the project fits and adjust as needed before investing in a more durable, high-quality fabric, the city is first using lower-cost, quick-to-install materials to test and refine the design and materials before seeking to make them permanent.