When Chicago brags about its recently added bikeways, one item on the list is sharrows: By late 2015, the city had nearly 50 miles of streets painted with a bike symbol and arrows pointing down the middle of the lane, in a space shared with cars.
They also have protected and "buffered" lanes, regular bike lanes, neighborhood greenways, and off-road trails. But what do the sharrow-covered streets do?
They don't necessarily keep cyclists safer or convince more people to ride bikes. Preliminary research from a PhD student at the University of Colorado found that although bike lanes encourage more ridership and reduce the number of crashes, a street with sharrows doesn't seem to do either.
"Sharrows have always been interesting to me," says researcher Nick Ferenchak, whose paper is under peer review now. "I have maybe a mile or two stretch on my commute where a bike lane transitions to sharrows, and I've always just wondered—is that actually doing anything for me as I'm riding my bike?"
It's possible that they might serve other purposes, he says. "The purpose might just be way-finding, putting them on streets that are already friendly for bicycles, to just help bicycles navigate through specific routes. But when we put sharrows on streets that aren't already bicycle-friendly, it doesn’t make them any safer."
A previous study of streets in Toronto and Vancouver found that streets with sharrows might even be a little more dangerous than a street with nothing bike-related at all.
Despite no evidence they really help cyclists, sharrows are increasingly popular in cities across the U.S. "Bike lanes take up space, they're expensive, you have to maintain them—putting a sharrow down is just a little piece of paint, it's 10 minutes, costs a few dollars, and then cities can say 'We have 100s of miles bike infrastructure, we're so progressive!'" says Ferenchak. "But is that actually bike infrastructure?"
"I just want to start the conversation," he says. "I don't want to say never put any sharrows in, but we have to think about what they're actually doing."