Traffic Calming

Under the Seattle Municipal Code, the speed limit on our non-arterial streets is 20 mph. Most people travel under the speed limit when the street is 25 feet wide and there is parking on both sides. 

When there is no curb, cars park on the planting area and traveling vehicles tend to go faster. Consequently, SDOT focuses traffic calming funds on streets that have no curbs. Other considerations for prioritization are areas around schools, parks and/or other pedestrian generators.

Residents in any area of the City may still pursue traffic calming. The funding for actual devices is possible through Other Funding Sources. A variety of traffic calming devices can be seen in the Engineering Toolkit. The following measures focus on bringing the community together to raise awareness and educate drivers that they are in a neighborhood where there is a strong desire for them to drive responsibly.

Radar Speed Gun 

You can borrow a radar gun from your nearest Customer Service Centers to determine typical speeds vehicles travel. When you go in to pick up the radar gun, you will receive instruction on its use. Most people who borrow the radar gun find that there is not a speeding problem on their street. SDOT defines a speeding problem as 15% or more of the traffic is going five miles over the speed limit. 

Speed Watch Trailer

Speed watch trailer

The speed watch trailer detects and displays the speed of oncoming vehicles.  Placing the speed watch trailer on your street is another reminder to drivers to drive responsibly. 


Getting a ticket is a strong deterrent to speeding. SDOT works closely with the Seattle Police Department (SPD) on periodic enforcement where speeds are excessive on arterial streets or near schools where there is a significant safety concern.

Yard Signs

Yard sign

Yard signs are intended to inform drivers that they are travelling on a neighborhood street and remind drivers to slow down. Learn how to get free yard signs for your neighborhood.

Parking Management

Street parking

Parking on both sides of the street can be an effective traffic calming tool. On wide open streets, some drivers can feel 'encouraged' to travel at high speeds.  Narrower streets force them to slow down.  On this street, if a driver faces an on-coming vehicle, each driver must find a spot to maneuver so they can pass.

Painted Intersection

Painted intersection

Painting a mural at an intersection can help give your community a sense of place, and is a great way to organize your neighborhood around a common goal.  Painted Intersections may have indirect effects on helping to slow traffic in your neighborhood by making drivers aware that this is a socially organized neighborhood, and helping encourage them to be respectful of the people that live there while driving down your street. Additional information about painted intersections is available in Client Assistance Memo 2506.