Do lower speed limits make roads safer?

Recently, the Washington State Department of Transportation lowered the posted speed limits on Aurora Ave in Shoreline from 40 mph to 35 mph.

This provoked, shall we say, “strongly held opinions” from some drivers on social media.

A social media post from the city of Shoreline announces lower speed limits on Aurora

Almost ten years ago, Seattle lowered speed limits city-wide.

According to follow-up studies, just lowering the speed limits alone and only posting new signs, without increasing law enforcement, and without reengineering the roads resulted in a 22% reduction in all crashes.

And the studies found there was also an 18% reduction in the worst crashes: the crashes that kill people and cause permanent, serious injuries.

Data from a Seattle study showed that lowering speed limits city-wide reduced crashes and speeding.

Last year, the neighboring city of Lake Forest Park reduced speed limits to 20 mph on local streets and 25 mph on arterials.

But, unlike neighboring cities, and despite the safety benefits, the city of Shoreline has been reluctant to lower speed limits city-wide.

The Shoreline city council reviewed a study that recommended lowering speed limits to make roads safer in 2021. But after debating the data and evidence, the Shoreline city council pumped the brakes and slightly lowered speed limits on only some roads.