San Francisco has transit-only lanes on 30 miles of streets and plans to add 20 more miles in the next decade. It has even highlighted some busy lanes with red paint to make them more visible to drivers, resulting in fewer cars blocking the lanes. The SF Municipal Transit Authority filed a 2017 report analyzing the effect of red, designated transit lanes over a three year pilot period.
Zendrive analyzed 100,000 driver trips in a recent study of a new dedicated lane for public transit on a major San Francisco street, and found major reductions in excessive speeding, acceleration, hard braking, and risky phone use.