We are looking at the intersection of Commonwealth Avenue eastbound with Charlesgate East. Note the green-carpet-painted bike lane coming in from the left side of the picture.

What is the vertical green bar in the picture? Clearly, it is intended to be a bike box, with the bicycle symbols in the two travel lanes closest to the bike lane. The intention is to direct bicyclists to swerve across in front of two lanes of motor traffic, to continue on the left-side bike lane partly hidden under trees at the right side of the photo. But the bar extends across all four travel lanes, suggesting that bicyclists swerve across four lanes. as they might to make a U turn. Is there any special signal timing to warn bicyclists that the signal is about to turn green as they swerve across? The aerial (or satellite) photo appears to have been shot just after the traffic light had turned red for Commonwealth Avenue -- note cars still in the intersection, while traffic is queuing at the left side of the photo. Motor vehicles are encroaching into the bike box/crosswalk in three of the four lanes. A look farther to the east along Commonwealth Avenue confirms the signal timing -- there are moving vehicles in the travel lanes there. (Click on the up arrow at the top of this page to get to the index page with the map.)