Q: Large cities with busy pedestrian populations frequently utilize a stoplight system at busy intersections when there is a period where all traffic is stopped and all pedestrian crossings signal “walk.” Then traffic flows when all are “don’t walk.” This eliminates the simultaneous cross-flow of pedestrian and traffic. Why hasn’t Ann Arbor implemented this fairly simple measure at busy crossings?
A: “The situation you describe is often referred to as a ‘pedestrian scramble’ whereby an intersection signal is programmed to allow for an exclusive pedestrian crossing in all directions,” emails Ann Arbor transportation manager Raymond Hess. The downside is that “it lengthens the wait time for everyone using that intersection: pedestrians, cars, buses, and bikes.”
While the pedestrian scramble “continues to be considered on a case-by-case basis, especially if this measure would have demonstrable safety benefits,” Hess writes, the city has chosen instead to program “all city-controlled traffic signals to have leading pedestrian intervals (LPIs). Signals with LPIs give pedestrian crossing signals a 3 second ‘head start’ before the vehicle signal turns green. According to the Federal Highway Administration, this measure has the benefits of: increased visibility of crossing pedestrians; reduced conflicts between pedestrians and vehicles; increased likelihood of motorists yielding to pedestrians; and enhanced safety for pedestrians who may be slower to start into the intersection.”
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