[M II A II R II K]

The Sharrow


March 28, 2010



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On the confirmation side, Trevor Haag, 22, who lives in University City, turned his cycling enthusiasm into a study of shared-lane markings on narrow streets — stylized arrows and bike symbols called “sharrows.” The question he tackled was whether driving and cycling behavior changes in the presence of these markings.

“I didn’t think it would have a significant effect on behavior,” Haag said, and therefore formal bicycle lanes would seem to be the safest way to separate cars from bikes.

Haag did his field work on Pacific Street in Oceanside, among the county’s first use of sharrows markings. He noticed that motorists tend to steer away from the space marked by the arrow and bike symbol and cyclists lean to the left side of the markings away from parked cars, when at any moment a driver could open a door and cause an accident with oncoming rider. Earlier, he surveyed users of the street, and few realized the markings were there

“I was really surprised how the surveys and field research contradicted each other,” he said. “I expected people would change their behavior if they noticed the markings, but I didn’t have a strong reporting of it.”

He checked narrow streets in Pacific Beach where there are no markings and found driving and bike-riding behavior were not as safe.

The conclusion: Caltrans engineers knew what they were doing when they painted the sharrows markings — motorists subconsciously look out for cyclists when there is a periodic reminder painted on the pavement.

“These findings contradict the popular belief that drivers and bicyclists are cognizant of their routine actions,” Haag said in his 21-page paper.