Friday, January 7, 2011

Taxi Driver Complains about New Signal Timing on Masonic: Best Indicator of Change

Southbound drivers on Masonic may notice change in signal light timing

No good reason to speed traveling north on Masonic

When a taxi driver complains that it's no longer possible to exceed the speed limit, you know traffic signal changes are working. That's what seems to be happening on Masonic Avenue after the southbound signals were adjusted late last year to keep traffic moving at the 25 mph speed limit. Javad Mirabdal, city traffic engineer and project manager for the Masonic Avenue Street Design Study, said the complaint was one indication that the changes were having an impact. "Taxi drivers basically know every street," Mirabdal observed. "They know when changes are made." The driver called the San Francisco Municipal Transportation Agency (SFMTA) and reported he was hitting red lights while travelling southbound on Masonic.

With the change in timing, motorists travelling south from Geary to Fell will find generally that when they exceed the 25 speed limit, they'll get more red lights. Mirabdal said the agency adjusted the signals in the southbound and downhill direction because that's where drivers tend to go faster. He added, "Timing will control the platoon of traffic, but it doesn't control speed for the ending (those drivers at the end of the pack)." Mirabdal explained that those in the back may have an opportunity to catch up with the traffic flow and momentarily exceed the speed limit. "It depends where you are in the platoon."

Only the southbound signals have been adjusted since two-way traffic, as on Masonic, poses too many traffic engineering problems to make bi-directional adjustments. "Once you push one direction, you limit what you can do with the other," Mirabdal said. One-way traffic roadways are the ideal candidates for the best outcomes from signal timing changes.

The signal adjustments were one of several traffic calming measures that Masonic area neighbors have asked the SFMTA to study and implement during the period before the full treatment for a better Masonic begins. The SFMTA has yet to respond to the other interim measures. Mirabdal said the final report with recommendations for comprehensive traffic calming on Masonic would likely be completed by the end of next week. The report will be posted on the SFMTA website.

For previous stories in the A Better Masonic series, check here.

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