The recent changes to the Seattle speed limit have been a long time coming, but are just an incremental step in a larger plan for safer streets. 

The process of setting speed limits for streets and highways is surprisingly complex.

Maximum speeds are set by each state legislature, which must balance the interests of stakeholders statewide. The social costs and benefits of lower speeds often lose in a head-to-head competition the economic and political benefits of higher speed limits.

Historically, lawmakers have prioritized speed over safety. The consequences have been deadly.

“U.S. streets have long been designed to promote speed at all costs, with deadly consequences”

Linda Bailey, Executive Director of NACTO

The irrefutable fact is that excessive speed causes more crashes—and increases the odds of fatalities in those crashes.

Setting Washington State speed limits

Our state law gives considerable latitude to city and county entities, including Washington State Department of Transportation (WSDOT) and Seattle Department of Transportation (SDOT), to increase or reduce speed limits.

In recent years, the Washington State Legislature has given localities more ownership over setting speeds and managing their roadways.

That could mean allowing higher speeds in some areas. Under Washington State law, freeways can theoretically have speed limits up to 75 mph. But the most recent attempt to increase the speed limit to 75 mph on I-90 in eastern Washington was shut down after a safety study.

In most places, including Seattle, speed limit reduction has become the goal.

Seattle speed limit changes

SDOT sets Seattle speed limits, but WSDOT manages the state routes—like SR 99. Recently, state and local agencies have worked together to make Seattle streets safer for everyone.

In March 2021, SDOT and the Mayor’s office launched a program to uniformly lower speed limits to 25 mph on most arterial streets.

With the approval of WSDOT, SDOT also started lowering speeds by five miles per hour on sections of state routes.

Case study data provides ample justification for these changes.

Lower speed, more signs: a study on injury crashes in North Seattle has surprising results…

Previously, the speed limit signs were spaced at least a mile apart in each direction on many streets. Or worse, there were no speed limit signs at all. No signage means drivers should follow the state’s default speed limit—which was not particularly clear.

Now, all completed streets include new reduced speed signs spaced every quarter-mile in each direction. On some state routes, the new signs are bigger and more visible.

Setting a consistent Seattle speed limit of 25 mph helps to create predictability for drivers. Adding speed limit signs provides regular reminders.

These are great changes, but they are just one step in the right direction in making our city streets safer for all Seattle residents.

– Attorney Kevin Coluccio, Seattle