Seattle Recalculates Walk Signal Timing to Make Crossings Safer for Pedestrians

The new formulas for calculating the length of walk signals are designed to give people more time to safely cross the street.

April 2, 2021, 7:00 AM PDT

By Diana Ionescu @aworkoffiction


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"Determining how much time a pedestrian needs to safely cross the road at a crosswalk is surprisingly complicated," writes Michelle Baruchman in the Seattle Times. City engineers employ "a set of formulas that consider the width of the street, an average walking pace and intersection design, among other things" to calculate the amount of time needed for each intersection. Until recently, the Seattle Department of Transportation (SDOT) used an average walking speed of 3.5 feet per second. "Now, through conversations with a pedestrian-focused advisory group, SDOT has updated its guidelines to give people a little more time to cross — a move celebrated by advocates for seniors and people with disabilities."

Pedestrian advocates applaud the move as one of many possible "seemingly small tweaks" that "can make a big difference in street safety, without requiring major construction or costs." Akira Ohiso, a social worker with Sound Generations, an organization that provides activities for seniors, cited prior conditions as unsafe, saying that "crosswalks in busy urban streets do not allow enough time for older adults to cross safely, especially four-lane streets." The new guidelines call for recalculating the timing "when existing intersections are modified, when community members request a change and when new signals are installed." For drivers, the changes will "mostly balance out," according to SDOT spokesperson Ethan Bergerson, as "slightly longer red lights usually also lead to longer green lights."

The change comes as part of a broader move to improve pedestrian safety in the city that includes curb bulbs, leading pedestrian intervals, and guidance on whether intersections require push-to-walk buttons or automatic signals.

Monday, March 29, 2021 in The Seattle Times

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