Traffic calming faces bumpy road

Residents of San Mateo's Aragon neighborhood are embroiled in a debate over the use of "speed cushions" to slow traffic on Edinburgh Street.

The city's public works department, at a meeting last Wednesday, summarized the results of a speed study to residents of the neighborhood and left them to discuss the implications. With the official meeting over, the residents opted to stay and continue the lively talk.

The study showed that drivers on residential Edinburgh Street had slowed down by about 5 mph since the city installed temporary rubberized "speed cushions" there last year at the residents' request. Six out of every seven cars were now obeying the street's 25 mph speed limit.

To plenty of Edinburghers at the meeting, that sounded like a smashing success -- proof that the hard-won traffic-calming devices should be installed permanently, in asphalt form. But their view was hotly contested by residents of neighboring streets, highlighting the tensions inherent in the city's efforts to respond to concerns about speeding.

Bruce McNamara, a resident of nearby Sonora Drive and a member of the neighborhood steering committee on traffic calming, said he wasn't convinced that the speed cushions solved anything.

The catch is that while speeds on Edinburgh decreased, so did the number of cars. Where did they go? Judging from the study, at least a few may have avoided the speed cushions by using even smaller streets nearby, such as Sonora Drive and Castilian Way.

Of course, that's tough to prove. Larry Patterson, the city's public works director, explained that speed studies come with a certain degree of statistical "noise" because conditions can vary from day to day.

So the question of the day at Wednesday's meeting was whether the increases in traffic measured on Sonora, Castilian and other streets were big enough to be significant. It was a question the city declined to answer.

"We don't want to take sides," Patterson said. "If we step in and say, 'This is below threshold of any significance, you end up with half the room ready to tar and feather you.'"

Instead, the matter will be resolved democratically. The city is asking area property owners to vote on whether the cushions should stay or go. The results of the mail-in ballot will go to the public works commission on Feb. 14 for a final decision.

This will likely be the last time the city installs cushions for a test period before deciding whether to put them in permanently, Patterson said.