John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
A year after the city built four styles of protected bike lanes, one design stands out as problematic.
Last fall, San Francisco rolled out its first raised bike lane on downtown’s busy Market Street. The short, experimental lane incorporated stretches of different design types: some with sloped curbs and some with 90-degree curbs, wider versus narrower paths, and different heights relative to the sidewalk. The goal was for the city to study what works and what doesn’t in bike-lane design.
Well, the San Francisco Municipal Transportation Agency has published a thorough analysis of the lane’s first year, and one thing that appears not to be working so great is the 90-degree curb (“Option D” below). That section of pathway was the site of at least two collisions, according to the analysis, one resulting in a “major injury” when a cyclist tried to enter the raised lane. These accidents will no doubt come into discussion as the agency continues to install raised paths throughout the city. (An SFMTA spokesman said Thursday evening he was looking into the accidents.)
Despite the collisions, the part of the lane with the vertical curb showed some benefits. In fact, about a third of people interviewed by SFMTA said they liked it best, partly because it is perceived as a barrier to vehicles entering the bike lane. However, if you combine the two designs with 6-inch-wide sloping curbs (one is closer to sidewalk level), survey respondents liked this option better. These designs allow cyclists to enter and exit the lane without much deceleration, though anyone who’s actually ridden on them knows they don’t prevent motorists from intruding onto the path for parking, unloading, or other reasons.
Whatever kind of raised lanes the city rides with in the future, in some places it’s likely to implement additional safety measures, such as painting the lane green or installing safe-hit posts to keep cars out. Here’s more about the Market Street pilot from the SFMTA’s blog:
Based on the evaluation, for busy commercial streets like Market we recommend a bikeway design that’s level with the sidewalk (similar to that in option C), has a vertical curb (as used in option D) and includes buffer areas between both the traffic lane and the sidewalk.
For protected bike lanes to work in commercial areas in general, ideally they should have a parking-protected configuration, with a lane of car parking and loading zones between the bike lane and roadway. If the bike lane is level with the roadway, it should be separated from the road by a concrete curb or median.
Mountable curbs, which are angled so vehicles can roll up them if necessary, tend not to be effective deterrents to illegal parking in commercial areas.
If further measures are needed, we recommend adding green paint to make them more visible and using plastic safe-hit posts to separate them from the road where appropriate.
On Market, where three of the four sections of our raised bikeway had mountable curbs, incursions by delivery trucks and other vehicles remained common. Last month, we installed safe-hit posts along the entire raised bike lane, which has helped prevent this from happening.