Radar Speed Sign

Radar speed signs use radar to detect and display the speed of passing motorists. These signs are normally placed on arterial streets with chronic speeding issues.

Radar speed signs can also be temporarily displayed via a trailer. A radar speed trailer is normally deployed for a few days to remind drivers to travel the speed limit.

How does SDOT consider where to install a radar speed sign?

  • If 15% of people drive five miles per hour or more over the speed limit a radar speed sign may be considered.
  • While the sign is in place, we might be working on more permanent design strategies.
  • In other places, such as at construction sites or around schools, we might deploy a radar speed trailer to remind drivers to follow the speed limit.

How does the community request a radar speed sign?

The community might choose to pursue funding sources such as Your Voice Your Choice or the Neighborhood Matching Fund.

How much does a radar speed sign cost?

$1,500 to deploy a radar speed trailer and $25,000 to install a permanent sign (on an arterial street).

How long does it take to install a radar speed sign?

Three months to a year. 


Greg Spotts, Director
Address: 700 5th Ave, Suite 3800, Seattle, WA, 98104
Mailing Address: PO Box 34996, Seattle, WA, 98124-4996
Phone: (206) 684-7623

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The Seattle Department of Transportation (SDOT) is on a mission to deliver a transportation system that provides safe and affordable access to places and opportunities for everyone as we work to achieve our vision of Seattle as a thriving, equitable community powered by dependable transportation.