Thursday, April 22, 2010

Colored Bike Lanes, Comm. Ave EB at the BU Bridge

Posted by Shannon Brown

Commonwealth Ave is one of Boston’s busiest corridors and runs through most of the city, including the Boston University campus. This major road is particularly busy as it cuts through the campus; carrying not only cars but many pedestrians on the sidewalks and student bicyclists in the streets. With the increased demand for safer riding conditions for the bicyclists that frequent this street, the city of Boston installed 5-foot bike lanes in 2008 and colored them green at the intersection of Commonwealth Ave and University Rd, leading to the BU Bridge.

Commonwealth Ave is a two way road with three travel lanes on each side and T tracks running through the middle. At the intersection there are three 11 foot travel lanes on each side as well as right-turn lanes to the right of the bike lane which causes drivers to cut across the bike lane in order to get into the right turn lane. The solid colored bike lanes are placed in this area of heavy traffic in order to warn vehicles that cross the bike lanes that they are to yield to a cyclist should there be one present. From on-site observations, I found the painted lanes to be mostly effective when a cyclist was present. For example, when a vehicle wanted to cross the bike lane to get into the right-turn lane, more times than not they yielded to the bicyclist. The times when the prominent colored bike lanes were not effective in getting this message across were when many vehicles were turning left onto Commonwealth Ave from Mountford St. Oftentimes there would be congestion as vehicles were waiting to turn right onto the BU Bridge from Commonwealth, and the bike lanes would be blocked; causing bicyclists to weave around standing cars.

Another issue with the setup of this intersection is that there is no bike lane with the right turn lane on the WB side of Comm. Ave. for cyclist wishing to turn right onto the BU Bridge. They must share the lane with motorists. As of right now this is more of an issue than normal due to the construction that is currently taking place on the bridge.

This is not an issue on the EB side of Commonwealth Ave because the turning lane does not start as far back. There is some normal conflict with the right-turn lane at the intersection with Essex St but the right lane continues across the bridge over I-90 to be a right turn lane for the intersection of Commonwealth and Carlton St. There is no bicycle-vehicle conflict at this intersection because the lanes have already been established prior to approaching the intersection.

Overall, the colored bike lanes are effective in notifying drivers when they are crossing a bike lane. The design of the bike lanes at this intersection is geared more toward through bike traffic on Commonwealth rather than cyclists who might be turning off of that road.


  1. Good analysis, pointing out that the paint works to give bikes priority over moving cars, but not over cars standing still due to congestion who often block the lane.

  2. Good job noticing the lack of a right-turning bike lane, when a lot of cyclists are turning right. A bike lane could easily be provided there, where the expected (and actual) behavior is for bikes to keep to the right while cars pass (or queue up) on the left.