With an average weekday ridership of 173,500 passengers as of 2012, Muni Metro is the United States' third-busiest light rail system after Boston and Los Angeles, operating a fleet of 151 light rail vehicles (LRV) with an average weekday ridership of 173,500 passengers.
The Muni Metro system consists of 71.5 miles (115.1 km) of standard gauge track, seven light rail lines (six regular lines and one peak-hour line), three tunnels, nine subway stations, twenty-four surface stations and eighty-seven surface stops.
All subway and surface stations are wheelchair-accessible. In addition, several surface street stops are also wheelchair-accessible, often consisting of a ramp leading up to a small platform for boarding. Above ground, there are twenty-four surface platform stations. Two stations, Stonestown and San Francisco State University are located at the southwestern part of the city, while the rest are located on the eastern side of the city, where the system underwent recent expansion as part of the Embarcadero extension and the Third Street Light Rail Project. However, many of the stops on the system are surface stops consisting of anything from a traffic island to a yellow-banded "Car Stop" sign painted on a utility pole.
Muni Metro has two rail yards for storage and maintenance:
The Rail Vehicle Maintenance group is responsible for providing clean, safe and reliable rail vehicles in sufficient numbers to provide scheduled service levels to the riding public of San Francisco on a daily basis.
Rail Vehicle Maintenance is responsible for maintaining 151 Breda light rail vehicles, 52 historic rail vehicles and 40 cable cars (28 Powell Line cars and 12 California Line cars). We work safely and efficiently to provide direct on-vehicle maintenance including:
In addition to direct vehicle maintenance the Rail Vehicle Maintenance group maintains a full-service Machine Shop with two satellite locations, Electric Motor Shop, Sheet Metal Shop, Electronic Shop and HVAC repair shop. These support shops repair and overhaul components that have been removed from the vehicles and fabricate new components when necessary. The support shops provide support to the rubber tire fleet, cable car infrastructure as well as light rail vehicles and historic vehicles.
On February 18, 1980, the Muni Metro was officially inaugurated, with weekday N Line service in the subway. The Metro service was implemented in phases, and the subway was served only on weekdays until 1982. The K Ingleside Line began using the Metro subway on weekdays on June 11, 1980, the L Taraval and M Ocean View lines on December 17, 1980, and lastly the J Church Line on June 17, 1981. Meanwhile, weekend service on all five lines (J, K, L, M, N) continued to use PCC cars operating on the surface of Market Street through to the Transbay Terminal, and the Muni Metro was closed on weekends. At the end of the service day on Sunday, September 19, 1982, streetcar service on the surface of Market Street was discontinued entirely, the remaining PCC cars taken out of service, and weekend service on the five light rail lines was temporarily converted to buses. Finally, on November 20, 1982, the Muni Metro subway began operating seven days a week. Current Muni metro service has expanded along the waterfront south of the Embarcadero and onto Third Street where it now terminates at the city line.