Muni Metro  The Muni Metro is a light rail system serving San Francisco, California, United States, operated by the San Francisco Municipal Railway (Muni), a division of the San Francisco Municipal Transportation Agency (SFMTA). With an average weekday ridership of 157,700 passengers as of the fourth quarter of 2019, Muni Metro is the United States' second busiest light rail system. Muni Metro operates a fleet of 151 Breda light rail vehicles (LRVs), which are being supplemented and replaced by Siemens S200 SF LRVs. Muni Metro is the modern incarnation of the traditional streetcar system that had served San Francisco since the late 19th century. While many streetcar lines in other cities, and even in San Francisco itself, were converted to buses after World War II, five lines survived until the early 1980s, when they were rerouted into the newly built Market Street subway. The system today traverses a number of different types of rights of way, including tunnels, reserved surface trackage with at-grade street crossings, and streetcar sections operating in mixed traffic; surface stops range from high-platform stations to traditional curbside streetcar stops. Recently, the system has undergone expansion, most notably the Third Street Light Rail Project, completed in 2007, which started the first new rail line in San Francisco in over half a century. Other projects, such as the Central Subway, are underway. The first street railroad in San Francisco was the San Francisco Market Street Railroad Company, which was incorporated in 1857 and began operating in 1860, with track along Market Street from California to Mission Dolores. Muni Metro descended from the municipally-owned traditional streetcar system started on December 28, 1912, when the San Francisco Municipal Railway (Muni) was established. The first streetcar line, the A Geary, ran from Kearny and Market Streets in the Financial District to Fulton Street and 10th Avenue in the Richmond District. The system slowly expanded, opening the Twin Peaks Tunnel in 1917, allowing streetcars to run to the southwestern quadrant of the city. By 1921, the city was operating of electric trolley lines and of cable car lines. The last line to start service before 2007 was the N Judah, which started service after the Sunset Tunnel opened in 1928. In the 1940s and 1950s, as in many North American cities, public transit in San Francisco was consolidated under the aegis of a single municipal corporation, which then began phasing out much of the streetcar network in favor of buses. However, five heavily used streetcar lines traveled for at least part of their routes through tunnels or otherwise reserved right-of-way, and thus could not be converted to bus lines.