According to the city of South Beach, CA, the
green lane on 2nd Street has increased cycling in the travel lane, outside the door zone, by 300% since its installation. The green lane is essentially a paint and center-of-the-lane sharrow treatment that advertises the legitimacy of cyclists controlling the travel lane as drivers of vehicles. It doesn't "separate" or "protect" cyclists; it essentially just tells them "to get out there and mix with traffic" while at the same time telling the motorists to accept it. It seems to be working. 300% is nothing to sneeze at. I wish more cities had this kind of courage to endorse proper bicycle driving where drivers can't pass without changing lanes.
I like the green lane because it markets cycling, which cycling advocates including myself want, but it doesn't require cyclists to operate according to different rules than other drivers or force them to use a separate facility with greater conflicts with junction traffic, car doors, pedestrians, etc.
I am concerned about some other sharrow installations, however, that have been placed on the right edge of marginal width lanes. I believe that sharrows should be used to market the legitimacy of cycling anywhere in the lane, and not be placed where they could be misconstrued as directing cyclists to ride curbside or too close to parked cars.