Pedestrian "head start" signal timing, also referred to as "leading pedestrian interval" or "early release timing", and is a way to improve pedestrian safety and comfort at busy intersections. The technique is to hold all cars for a few seconds while pedestrians are given a "Walk" symbol. After pedestrians have entered the intersection, vehicles are less likely to try to preempt their right-of-way when making turns. The City and County of San Francisco Department of Parking and Traffic (DPT) recently implemented this signal-timing plan at tow intersection in downtown San Francisco-3rd & Folsom Streets and 3rd & Howard Streets. Both of these intersections have dual turn lanes, with northbound 3rd Street traffic turning right onto Folsom and left onto Howard. These signal timing changes were based on requests from pedestrian groups and seniors in the area. DPT conducted a before and after study for the five-second timing plan, observing pedestrians and vehicles for one hour in the afternoon. They defined a pedestrian right-of-way (ROW) violation as a case where a car cut in front of a pedestrian crossing in the crosswalk on the green light. If the car waited until the pedestrian has passed, but had not yet reached the curb, was not counted as a ROW violation. Northbound pedestrians (leaving from the near side of the intersection next to the right turn lane) had their ROW violated by 3.8% of the time prior the head start timing. After the change, the percentage dropped to 0.9%, a 76% drop. After one year, when the head start interval was changed to 4 seconds, the number of ROW violations remained low-0.4% or an 89% drop from the original "before" condition. The southbound pedestrians (leaving from the far side of the intersection facing northbound right turns) had their ROW violated 20.6% of the time before the study and 7.2% afterwards (a 65% drop). After one year, even with only 4 seconds of head start timing, the number of ROW violations was only 0.7%, a 98% drop from the "before" conditions.


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  • Pagination: 3p

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Filing Info

  • Accession Number: 00803447
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Dec 19 2001 12:00AM