Bicycling

"Bike bays" make left turns safer

by Dan Malouff   •   December 6, 2012 1:46 pm

As American cities become more cycling friendly, bike lanes themselves are becoming more diverse. The toolbox of street design options available to planners is broadening to include new tricks and layouts. One such new bike facility is the "bike bay," which make left turns across traffic safer.

Bike bays, also sometimes called Copenhagen Lefts, combine the functions of a bike box, which provides a waiting zone for turning bikes, and a bike sneak, which directs cyclists onto a particular riding angle. The idea is to have cyclists who want to turn left exit off the main bike lane and onto a separate slip lane on their right, which then curves around 90 degrees and allows them to cross perpendicular to the original lane.

The idea should be familiar to anyone who has driven much in New Jersey, where the "New Jersey left" or "jughandle" essentially performs the same function for cars on state highways.

San Francisco recently opened a bike bay at the corner of Market Street and Valencia Street, where about 1/3 of cyclists going south on Market turn left, crossing over multiple lanes of traffic. Complicating matters, Market Street has streetcar tracks, which cyclists turning left have to cross over. Without the streetcar tracks a normal bike box might do the trick, but with them the bike bay is better.

Another example of a bike bay can be found in Cambridge, Massachusetts, right outside Harvard University at the corner of Massachusetts Avenue and Church Street. There a median separates the northbound lanes from southbound, preventing cars from turning left. Rather than forcing left-turning cyclists to cross over 2 lanes of cars and rush to make a sharp turn at the curb cut, it's better to have them cross perpendicularly, with the crosswalk.

But since the crosswalk is at a major entry gate to Harvard, there's a lot of pedestrian traffic, making it desirable to separate bikes from both cars and pedestrians. Thus a bike bay, which gives cyclists their own space right next to the crosswalk.

So far there are no bike bays in the DC area, at least as far as I know. But it's one more potential tool to use at complicated intersections. With more bike lanes and more streetcars on the way, it's possible this may someday be a useful concept for our region.

Cross-posted at BeyondDC.