Concord Avenue west of rotaries,
Cambridge, Massachusetts

In 1998-1999, Concord Avenue was restriped with three travel lanes, plus bike lanes. This configuration is much more attractive for bicycling, and does not significantly increase congestion for motorists. The two lanes eastbound (far side of the Avenue in photo below) allow left turns without bringing other traffic to a stop. The Avenue borders Fresh Pond Park, where there is only one lightly-used entrance -- at a signalized intersection, so there is little problem with left-turning traffic's blocking through traffic in the single westbound lane.

The bicyclist in the photo below exemplifies the saying "you can lead a horse to water but you can't make him drink." This bicyclist is probably coming from Fresh Pond Park and/or planning to turn left after the park, and he wants to avoid having to make a left turn across the Avenue. There is little pedestrian traffic on the south sidewalk, as there are few destinations along it.

Note also the transit bus stopped in the bike lane. It is correct of the bus driver to merge into the bike lane. Stopping outside the bike lane would encourage bicyclists to pass the bus on the right, risking collisions with passengers who are getting on and off the bus. However, bicyclists riding on the sidewalk also risk such collisions.

All in all, the restriping of Concord Avenue has resulted in a significant improvement in bicycling conditions. The improvement is achieved by the reduction of the number of travel lanes. The bike lanes amount to window dressing, as bike lanes so often do, but fortunately, they do not cause many problems here. Guide stripes without bike lane designation would in this author's opinion have been preferable, because they would not encourage motorists to stay outside the bike lane before turning right. 

The Concord Avenue bike lanes end at the large rotary intersection with Alewife Brook Parkway (location A in aerial photo).