Designing Safer Streets

With a goal of eliminating traffic fatalities and serious injuries by 2030, we are being proactive and redesigning our streets to make them safer and more complete for all users.

A Complete Street approach

Complete Streets is a design goal for all SDOT projects. It is a comprehensive review of safety, how a street functions and the quality of the streetscape (trees, street furniture, etc.). On busier streets, one way to improve safety and keep traffic moving- is to turn a four-lane street into a two-lane street with a center turn lane. It also opens up space, providing opportunities for bike lanes, landscaping, widen sidewalks or more efficient transit. This type of design usually works well on streets with around 25,000 cars or less a day.

It might seem like changing the number of lanes would mean fewer cars could use the street, or that more congestion might occur. However, creating a turn lane in the middle allows vehicles to turn without blocking traffic; adding bike lanes creates more predictability; and a single lane of traffic helps manage drivers cutting in and out of lanes. There are a number of benefits to building complete streets.


Safer Streets for All. People drive closer to the speed limit. This is especially critical for people walking, traveling in a wheelchair, and riding a bike, as well as other drivers. When motorists move at slower speeds, they're better able to stop and prevent a crash.

Easier to Cross Streets. When people cross streets with four lanes they encounter a ‘double threat.' This is caused by drivers in the inside lanes not seeing them. Redesigning the streets makes it easier to cross.

Improved Bus and Freight Movement. Changing the road to two lanes usually means lanes can be a little bit wider. This makes it easier for freight and buses to travel.

Easier to Walk and Bike. Having a little extra road space means bike lanes or wider sidewalks may become an option. The more people are able to walk and bike the closer we are to being the walkable, livable city Seattleites want.

The results

The City of Seattle has transformed 36 different roads since 1972. We can confidently say that not only does redesigning our streets make them safer, but it keeps people and goods moving. The Federal Highway Administration agrees. A 2010 study looked at 30 redesigned street in Washington and California and determined there was a 19 percent reduction in collision rate.

Read our before and after studies to learn more.