Department of Transportation Scott Kubly, Director
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Neighborhood Traffic Operations: Traffic Calming Program

Radar GunUnder both state law and the Seattle Municipal Code, the speed limit on our non-arterial streets is 25 mph. Addressing community concerns about speeding requires active participation by residents, working in a strong partnership with Seattle Department of Transportation (SDOT). The majority of residents that start working with us realize that most drivers are traveling the speed limit, which is good news!! Please read through the following information, which provides an overview of the steps we’ll take in working with you, and let us know if you want to work with us to address speeding on your street.

Phase I

  • Step 1 - Preliminary Assessment

    SDOT staff will conduct a brief preliminary assessment and respond to you. If the preliminary assessment suggests that your street is suited for any of SDOT’s programs, SDOT will respond to you with information on those programs, including the Neighborhood Traffic Calming Program.
  • Step 2 – Neighborhood Speed Monitoring

    Neighborhood Speed Monitoring is an important step in the educational and enforcement aspects of the traffic calming program. During this step, you will collect information, using a radar speed gun, about vehicle speeds on your street. This information serves as a good “snap shot” of how drivers are behaving as they travel through your neighborhood.
  • Step 3 – SDOT Review

    Next, SDOT staff will compile the results of your radar speed gun data. We will calculate the “85th percentile speed”. This is the speed that 85% of drivers are traveling at or below, and is a good measure of overall driver compliance with the speed limit. If it appears that the 85th percentile is over 30 mph, SDOT will order a traffic study for the street.  If that study shows an 85th percentile speed of 30 mph or higher, the street will be considered for Phase II of the traffic calming Program.  If the 85th percentile speed is under 30 mph, residents are welcome to explore community-oriented traffic calming measures. These measures may consist of signs, parking management, and educational tools that encourage drivers on your street to slow down.

Phase II

If the 85th Percentile speed is over 30 mph, SDOT will work with the community to identify which (if any) Physical Traffic Calming Measures may be effective at  reducing speeds. All physical traffic calming measures have advantages and disadvantages, but there may be measures that are suitable for use on your street.  Streets identified for potential traffic calming projects are prioritized based on speed and funding.  Residents are also encouraged and supported if they apply for Alternative Funding.

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