Seattle traffic engineer: ‘Our street design is harming people’

A recent report released by the City of Seattle revealed that 2020 was the deadliest year for traffic-related deaths since 2013. While there are likely a few factors driving that increase, one city traffic engineer says it really comes down to the way Seattle’s streets are designed.

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A separate recent report cites reckless driving habits as one of the primary factors behind a nationwide increase in traffic deaths. Seattle traffic engineer Dongho Chang believes the problem is far more systemic than that.

“Our street design is harming people,” Chang said on Twitter on Tuesday. “Conforming to the rules is hurting and killing people outside the vehicle in urban cities where people are the priority.”

He cites rules that have engineers forced to prioritize “excess traffic lanes” that encourage speeding, as part of “conditions dictated by our profession.” Efforts to design streets in ways that prioritize pedestrian safety can often flout existing rules, too.

“In order to protect people quickly, we are forced to break the rules,” he described. “(Traffic design rules) must not be a barrier to safety of people outside the car.”

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In order to mitigate against that, Chang recommends organizing streets in ways that “reflect the community.” That means supporting lower speed limits, building out streets limited strictly to pedestrian traffic and community gathering spaces, and installing “speed mounds” that significantly slow vehicle traffic.

Let's add speed mounds for pedestrians in our professional street design tool box pic.twitter.com/5puvP8aayw

— Dongho Chang (@dongho_chang) March 23, 2021

Seattle made progress toward at least one of those goals in early March, when it finished lowering speed limits on most city streets to 25 miles per hour. That was a decision driven by case studies indicating “a 20-40% drop in crashes on streets where Seattle lowered speed limits.”

But it’s also going to take more than simply lowering driving speeds, Chang argues, stating that context is what really matters when it comes to designing city streets versus freeways.

For freeways, he points out how “uniform design matters.” But for residential, urban streets, “place matters.”

“Small changes can have big impact on how we perceive and experience our streets,” he said. “It can also significantly improve safety.”

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