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Consider, if you will, the lowly sharrow. This awkwardly named symbol, painted in bright white on asphalt, combines a bicycle and an arrow. It’s intended to indicate that a lane should be shared on equal terms by people on bikes and people driving cars.

Accepted as a standard marking by the Federal Highway Administration since 2009, the sharrow is one of the least-loved types of bicycle infrastructure. It can be confusing to drivers who have never encountered it before, and is frequently dismissed by cyclists as an ineffective, cheap fix that allows cities to say they are accommodating bikes without committing much space, money, or political capital to the effort. ( Read the comments on this excellent Greater Greater Washington piece about sharrows to get an idea of the most common objections.)

Despite the haters, research shows that sharrows can have positive effects. A 2010 study done by the city of Austin, for instance, concluded that sharrows were “effective at reducing unsafe bicyclist behavior” and also “resulted in improved motorist behavior.” Like them or not, as a result of conclusions like these, sharrows have become increasingly common in cities around the country.

But what if transportation planners could create a better sharrow? That’s the question that prompted Oakland, California, to launch an experiment in 2013. The city tested what came to be called a “super sharrow,” in which the symbol is painted in white atop a five-foot-wide green strip down the middle of the lane.

City of Oakland

The marking—which is modeled on similar treatments in Salt Lake City, Minneapolis, and Long Beach, California—aims to clarify where people on bicycles should be riding. It’s designed to help riders to stay safe on a route without a dedicated bike lane—out of the dangerous “door zone,” where they can get clipped by drivers exiting parked cars. It’s also meant to reinforce drivers’ respect for the cyclists’ right to “take the lane,” as well as safe passing.

The super sharrow was striped on 40th Street in downtown Oakland, a heavily traveled and increasingly popular bike route near the MacArthur BART station that has long been a problem area for the city’s bike-network planners. The street has two travel lanes in either direction, a landscaped median, and parking on both sides. It is also an important bus route. Because of the competing demands of all these users and constituencies, says Jason Patton, Oakland’s bicycle and pedestrian program manager, it proved impossible to create a dedicated bike lane on this stretch of 40th Street, despite three different attempts to do so.

These symbols reinforce the message that cyclists are legitimate road users.

Enter the super-sharrow experiment, which had three phases. In the first, the street had no markings for bicyclists. In the second, the right-hand travel lane was marked with standard sharrows. And in the third, the enhanced super-sharrow configuration was created in that lane. Signs indicating that people on bicycles had the right to use the full lane were also installed.

Analysis of the data, published in the Transportation Research Record, showed mixed results. With the super-sharrow treatment, the number of cyclists staying clear of the door zone increased by a statistically significant margin. On average, the passing distance observed by motorists was the same on super sharrows as on regular sharrows. But the variability of that distance increased: With cyclists were riding further to the left, some drivers moved farther left, but some didn’t, thereby passing closer to the people on bikes. Also, neither kind of sharrow had an effect on whether cyclists passed drivers at a stopped light on the right, in effect “jumping the line”—a practice that can put people on bikes at increased risk of right-hook collisions.

Travel speeds for autos and transit were unaffected by the sharrows or the super sharrows.

Despite these mixed results, according to a survey done by the city, 58 percent of respondents had positive feelings about the super sharrows. Patton says that the treatment was successful enough that the city would like to continue it, and possibly install similar markings on other corridors where alternative bike infrastructure is not feasible. That will depend, he says, on whether the FHWA ends up accepting the enhanced sharrows as a standard street solution.

Patton understands that people who ride bikes often see sharrows as a mere token effort at bike infrastructure. “I think these are very valid criticisms,” he says. But he adds that, in the case of 40th Street, “for various practical reasons we find ourselves in the situation where something is better than nothing.”

If nothing else, says Patton, the presence of sharrows is indisputable proof that cyclists have the right to use the lane. “At least it gives cyclists the moral ground to stand on if they get into that argument.”

And the highly visible marking, with the accompanying street signs, is just one more way of making the bicycle symbol a pervasive presence on the streets of the city. These symbols, says Patton, reinforce the message that people on bikes are legitimate road users. In that way, he says, the super sharrows are doing more than just marking the place for cyclists to ride.

“Developing a bikeway network—particularly an ‘all ages and abilities’ network—is a time-consuming task,” writes Patton in an email following up on our phone call. And if you’re taking the long view, super sharrows might help to point the way forward.