“Get in the bike lane!” the driver shouted as he rolled down his window at the red light. I didn’t expect an easygoing conversation. Angry drivers and cyclists rarely have a productive dialogue, especially after horn honks and arm gestures. But in this instance, I was more confused than anything else. There wasn’t a bike lane, or even a shoulder that might pass for one. I told the driver as much. Then he pointed to a symbol—a white bicycle outline topped with two chevrons—on the road. “There!” he said. “You have to ride there.”
For something that ought to help clarify rules of the road, the shared lane marking—more commonly known as the “sharrow”—can cause tremendous confusion. The distance between what it’s supposed to mean and how it’s actually used is a source of frustration for cyclists and drivers alike. But it doesn’t have to be this way. The sharrow, though often maligned and misunderstood, can have its proper place on our shared streets. That can only happen, however, if we understand its uses and limitations.
So let’s demystify the sharrow, perhaps the most divisive piece of the road cycling puzzle.
Sharrows first appeared in Denver in the 1990s, but the word itself (a portmanteau of “share” and “arrow”) was coined in San Francisco in the early 2000s. The term has been included in the Federal Highway Administration’s Manual on Uniform Traffic Control Devices—the traffic engineer’s bible—since 2009. Elaborated in the manual is what, exactly, sharrows are supposed to achieve.
First things first: A sharrow is not a bike lane, as it does not create road space nominally reserved for bicycles. Instead, it is meant to be used in situations where cyclists and drivers must coexist in the same lane. (Think slower-moving neighborhood streets; you’re never supposed to see sharrows in areas with speed limits above 35 mph.) Primarily, it’s a positioning tool that tells you where to ride to avoid both flung-open car doors and vehicles passing too closely. In theory, if you ride where the sharrow is placed, you won’t find yourself squeezed in a lane too narrow for cars and bikes together.
The sharrow also conveys information. It’s meant to help cyclists stick to recommended bike routes, avoid wrong-way riding, and find gaps where a bike lane might temporarily disappear. It should also alert drivers to the likely presence of bikes, encouraging them (supposedly) to move a little farther to the left if they want to pass a cyclist.
But do drivers and cyclists actually follow these directions? Maybe a little bit: According to FHWA spokesperson Neil Gaffney, multiple studies have found that sharrows “increase the distance by which motorists pass bicyclists, reduce wrong-way riding, and reduce the number of bicyclists riding on the sidewalk.” He pointed to a 2004 study conducted in San Francisco, which found that passing drivers tended to give cyclists more than two extra feet of space when sharrows were present. Additionally, a 2010 FHWA report found that cyclists generally had more space to maneuver after sharrows were installed on roads in Seattle; Cambridge, Massachusetts; and Chapel Hill, North Carolina.
The big question, then, is not whether sharrows can produce results, but whether they have come to replace cycling infrastructure that performs much better. After all, sharrows are easier to install, tempting planners to slap them down instead of face the political headache of carving out space for bike lanes (which might involve removing parking spaces for cars). But officials seem to agree that since they don’t establish any separated space for cyclists, sharrows are not an acceptable stand-in for the real thing.
“Shared lane markings should not be considered a substitute for bike lanes, cycle tracks, or other separation treatments where these types of facilities are otherwise warranted or space permits,” reads the Urban Bikeway Design Guide, put out by the National Association of City Transportation Officials. Sharrows can complement bike lanes, but they won’t bring the same kind of increase in cycling or improvement in bike safety.
This raises the additional question of whether sharrows are necessary at all. Most cyclists can already tell the difference between a quiet neighborhood street and a high-speed arterial where space and safety are bigger concerns. Will some extra paint on the ground really help that much?
New research indicates that it won’t. A 2016 study found that sharrows failed to dramatically increase the amount of bicycling on Chicago roads between 2000 and 2010. More notably, streets with sharrows saw less of a decrease in cycling injuries than streets with no bike markings whatsoever. “It is time that sharrows are exposed for what they really are, a cheap alternative that not only fails to solve a pressing safety issue, but actually makes the issue worse through a sense of false security,” the authors concluded.
Indeed, planners are beginning to turn away from sharrows. Darren Buck, bicycle planner for the District Department of Transportation in Washington, D.C., noted that their use has changed over time. “When sharrows were introduced, many in the bike community hoped that they might result in some driver behavior change around bicyclists, or that they would make many riders feel more comfortable on busier streets,” he told Bicycling. “We don’t think there’s a lot of evidence out there to support those hopes. We have moved away from installing sharrows on streets where the separate space of a bike lane would be more appropriate.”
Even bike advocates have grown skeptical. Liz Cornish, executive director of Bikemore in Baltimore, said, “I don't think sharrows are ever enough to overcome what in Baltimore can often be a pretty hostile experience sharing the road with people who drive. And because they are not used consistently, how would anyone actually know what they mean?”
Does Bikemore ever ask for sharrows as part of its advocacy? “Never,” Cornish said. “Our mission is to create a healthy bicycling city. That means we have to get more people riding. Enough cities have made this transition for us to know that is only possible when you commit to a network of high-quality protected infrastructure and multi-use trails. Sharrows don't even rank.” (Help get someone riding with Bicycling's exclusive Get Someone Riding Kit.)
Are sharrows completely useless, then? Some say they can still serve an important role.
“They can work great on naturally calm streets. I find them reassuring,” said Will Handsfield, a Washington, D.C.-based transportation planner and former policy advisor to the D.C. city council. “I would love if cities were more open to narrowing travel lanes for a block to fit in a bike lane, and maybe that will happen, but that’s not always the case.”
Sharrows offer a recognition of reality: Not every street has room for bike lanes and, in many cases, cyclists and drivers will be forced to interact. The goal of the sharrow is to make these interactions more predictable and safer, reducing the potential for conflicts that might arise when different road users try to share a common space.
The reason why sharrows have such a poor reputation, according to Handsfield, is their misapplication—when they appear on high-speed roads, for instance. “Engineers need to take more seriously their responsibility to not put sharrows where they don't belong,” he said. “It's not the tool that's wrong, but it's the way the tool has been mismanaged that gives it a bad rap.”
It’s hard to predict what the future holds for the sharrow. As cities build more bike lanes, the use (and abuse) of this road marking could slowly fade away. It might come to be seen as an intermediate step on the path to more bikeable streets. Or it might evolve, performing the same task with better design and greater visual distinctiveness. In the meantime, for all its flaws, the sharrow will continue to insist that everyone should just try to get along.
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