New York has its first physically separated bike lane on 9th Avenue, where the parked cars sit between the bike land and traffic, protecting riders. I emailed DDOT’s Chris Ziemann about the 15th Street reconfiguration, suggesting a similar lane there. Ziemann responded that “separating the bikes from traffic is safer for bikes along the block, but much more dangerous at the intersections because right-turning cars don’t usually expect bikes (or anything as fast as bikes) if they’re hidden by parked cars.”

Is this true, or false? Are there certain types of streets where physically separated bike lanes would work, and others where they would not? I rode down 9th Avenue in a taxi yesterday, and the bike lane there has fairly sparse parking; it’s not a solid row of parked cars all along the block. Could this make the difference, if Ziemann is right about 15th?

I don’t know the answer. As more cities try these lanes, especially U.S. cities with similar traffic situations, we will get more data. I hope Washington DC will experiment with these as well, so we can find out for sure. And I’ll keep looking for more information about the real safety implications. As with one-way streets, it’s tough to separate fact from fiction.

David Alpert is Founder and President of Greater Greater Washington and Executive Director of DC Sustainable Transportation (DCST). He worked as a Product Manager for Google for six years and has lived in the Boston, San Francisco, and New York metro areas in addition to Washington, DC. He lives with his wife and two children in Dupont Circle. Unless otherwise noted, opinions in his GGWash posts are his and not the official views of GGWash or DCST.