San Francisco has been taking more steps toward improving Muni's on-time performance by making sure drivers know when they are in transit-only lanes.
Since last year, the San Francisco Municipal Transportation Agency has been coloring these types of lanes with red paint.
New work on Third Street between Townsend and Jessie streets is expected to be complete by the end of the week.
Weather permitting, the agency plans to begin work in the coming weeks on eastbound Market Street between Fifth and 12th streets, westbound Market Street between Eighth Street and Van Ness Avenue, and Geary and O'Farrell streets between Market and Gough streets, except for the segment between Powell Street and Grant Avenue.
The first red-colored transit-only lanes appeared last spring as part of a pilot project on Church Street between 16th Street and Duboce Avenue to improve the movement of J-Church trains and 22-Fillmore buses.
During peak commute periods, the pilot reduced J-Church travel times from six to seven minutes to four to six minutes, a 10 to 13 percent difference, according to SFMTA spokesman Paul Rose.
"As a transit-first city, we need to be smart about how we improve transit to make it an attractive, reliable choice for San Franciscans," SFMTA Transportation Director Ed Reiskin said. "These lanes represent a low-cost measure to decrease travel time by reminding and preventing cars from using transit-only lanes."