Центральный тоннель метро в Сан-Франциско

Light rail tunnel in San Francisco, California

The Central Subway is a Muni Metro light rail tunnel in San Francisco, California, United States. It runs between Chinatown station in Chinatown and a portal in South of Market (SoMa), with intermediate stops at Union Square/Market Street station in Union Square and Yerba Buena/Moscone station in SoMa. A surface portion runs through SoMa to connect to the previously existing T Third Street line at 4th and King station. The project was initiated after the Embarcadero Freeway was torn down following the 1989 Loma Prieta earthquake, as activist Rose Pak "almost single handedly persuaded the city to build" the Central Subway to compensate Chinatown for the loss of the fast cross town connection. Originally set to open in late 2018, the subway initially opened with a weekend only shuttle service between Chinatown station and 4th and Brannan station on November 19, 2022. Full service as part of the T Third Street line began on January 7, 2023. With the addition of the Central Subway, the T Third Street line is projected to become Muni Metro's highest ridership line by 2030. The budget to complete the Central Subway was $1.578 billion. The project was funded primarily through the Federal Transit Administration’s New Starts program. In October 2012, the FTA approved a Full Funding Grant Agreement, the federal commitment of funding through New Starts, for the Central Subway for a total amount of $942.2 million. The Central Subway was also funded by the State of California, the Metropolitan Transportation Commission, the San Francisco County Transportation Authority and the City and County of San Francisco.

The tunnel is about long, including of non revenue tail tracks, and includes three subway stations; the surface tracks built as part of the project are long and include one surface station. These surface tracks begin at 4th and King and continue northwest along 4th Street to 4th and Brannan station. The line enters the Central Subway at a portal under the Interstate 80 viaduct. Yerba Buena/Moscone station is located under 4th Street at Folsom Street. At Market Street, the subway crosses under the Market Street subway, with a reverse curve to align under Stockton Street. Union Square/Market Street station is located under Stockton Street between Market Street and O'Farrell Street, with an outside fare control connection to Powell Street station. The line continues north to Chinatown station at Washington Street. The twin subway tunnels continue north under Stockton Street and terminate under Columbus Avenue near Union Street, where the opportunity for extracting the excavators existed. The platforms of all stations on the Central Subway can only accommodate two car trains, limiting the capacity of the line.

In 2000, the estimated cost of the Central Subway project was $530 million. By 2001, the cost had risen to $647 million and completion was projected for 2009. When construction began in 2012, the cost had reached $1.6 billion. the $840 million contract was up to $120 million over the budgeted amount, which took up nearly two thirds of the entire project's contingency. In particular, they note that Muni's own estimates show that the project would increase Muni ridership by less than 1% and yet by 2030 would add $15.2 million a year to Muni's annual operating deficit. Previous transit access to these areas was provided entirely on the surface through small blocks that feature intense pedestrian activity and narrow streets with multi modal street congestion. Other, lower cost rapid transit options were explored, such as bus rapid transit (BRT), but were rejected in part because these conditions do not support the basic features of efficient BRT operations. Compounding these conditions is the fact that many Chinatown residents are transit dependent and do not own cars, helping rationalize funding for a subway. The high ridership Muni bus lines serving Chinatown (e. g., the 1 California and the 30 Stockton) are typically over capacity. In October 2012, the Federal Transit Administration (FTA) announced it would provide $942.2 million for the project under its New Starts program after indicating it would approve the grant in January. This award included the recognition that better, more comfortable service for an already intensively used transit corridor, particularly for low income residents as in Chinatown, justifies the investment even if it does not attract a high percentage of "new" riders the way a new rapid transit investment might somewhere that is not already served by extremely slow, uncomfortable high ridership local service. Voters approved the Central Subway in 2003, and the alignment was selected in 2008. Ground was broken for the project on February 9, 2010, however, physical work did not begin until June 2012. The first phases of work included preparation of the tunnel boring machine launch site and headwalls for the Yerba Buena/Moscone Station.

The two tunnel boring machines (TBMs) are named "Big Alma" and "Mom Chung" (for "Big" Alma Spreckels and Dr. Margaret "Mom" Chung, respectively). Preparations for tunnel boring began on June 12, 2012, with the start of excavation for the TBM launch box on Fourth Street between Bryant and Harrison. and in late July 2013, "Mom Chung" began digging the tunnel for southbound T Third trains. "Big Alma" began digging north in November 2013 at a slightly faster rate, , compared to the average of "Mom Chung". The initial plan was to remove the two TBMs near Washington Square in North Beach in 2014 once boring was complete. On July 31, 2012, a lawsuit was filed in Superior Court by Marc Bruno and Save North Beach, a 501(c)(4) organization of North Beach merchants and residents who believed that the removal of the equipment on Columbus Avenue would cause permanent harm to the neighborhood near Washington Square. The petitioners pointed out in their suit that they are in favor of the city's "Transit First" policy and that they would favor the removal of the equipment if a subway stop was planned, approved and financed for their neighborhood. Muni General Manager Ed Reiskin announced a plan in December 2012 to extend the tunnel to Columbus and Powell, using the site of the long closed Pagoda Palace theater to extract the TBMs, with a potential option to purchase the Pagoda as the site of a future North Beach station. In 2013, MTA reached a lease agreement with the owners of the Pagoda to tear down the old building and use its site for TBM removal. This will reduce impact of construction on the public space. On June 11, 2014, "Big Alma" broke through to the North Beach extraction shaft at Columbus and Powell Street in North Beach, joining "Mom Chung", which had arrived on June 2. The arrival of the TBMs marked the completion the boring operation phase. The twin tunnels were fully complete by May 2015, when Mayor Ed Lee toured the project underground. Each completed tunnel is 8500 feet (2591 m) long and 20 feet (6 m) in diameter, supported by 1,750 concrete rings placed during the boring operation.

Residents and workers near the 4th Street portal and North Beach extraction sites noted an increase in the visible number of rats after construction began. Construction of the Union Square/Market Street station required closing Stockton Street just north of Market, which depressed traffic to retailers in Union Square. During the excavation, workers accidentally breached a water main in July 2014, causing basement level flooding in shops along Geary between Stockton and Grant. The ensuing cleanup took several days and required a few businesses to keep stores closed. Since Stockton Street has been closed between Geary and Ellis, starting in 2014, construction is suspended in December and the area is transformed into a pedestrian plaza known as "Winter Walk". Some have called for Winter Walk to be made a permanent year round fixture, but notable opposition included Rose Pak, who wanted to retain Stockton as a link from Market to Chinatown. Workers breached a natural gas pipeline in May 2015 while working on the Yerba Buena/Moscone station, forcing the evacuation of the nearby Yerba Buena Center for the Arts.

On September 20, 2022, the SFMTA announced that service in the Central Subway would begin on November 19, 2022. Initial service was a "soft launch", running only on weekends, while operator training continued on weekdays. This early service ran only between Chinatown station and 4th and Brannan station. The T Third Street line continued to use the Market Street subway during this period. Additional shuttle trains signed "S Chase Center" will operate between and for events at Chase Center. Initial ridership was "tepid" – the T only saw a modest increase in ridership, while the parallel route 30 and 45 buses saw small drops. In February 2023, the three subway stations averaged 2,966 daily boardings and 4,501 daily exits. Half the ridership was at Union Square/Market Street.

Ten permanent installations were built as part of the project: three at each subway station and one at 4th and Brannan. A draft of the Central Subway Arts Master Plan was presented to the San Francisco Arts Commission in September 2008. Artworks are divided into "landmark" and "wayfinding" categories. Candidates were announced in July 2010 and the winning entrants were announced that August. Temporary artworks were also installed during construction. "One Hundred Years: History of the Chinese in America", a mural painted by James Leong originally for the Ping Yuen housing project in Chinatown, was enlarged, printed, and wrapped in 2012 around the Hogan & Vest building at Stockton & Washington, at the future Chinatown station site, prior to that building's demolition. In addition, temporary murals were painted on the construction barricades erected around the Chinatown and Yerba Buena/Moscone stations. The art was printed on adhesive vinyl and wrapped onto the plywood panels, measuring approximately 2.44 m high by 57.91 m long at Chinatown, along Stockton, or 48.77 m long at Yerba Buena/Moscone, along Folsom. Temporary art was also installed around the Pagoda Palace Theatre from 2014 to 2017, while it was being used to extract the two tunnel boring machines.

A proposed third phase would build an extension beyond Chinatown, including new stations at Washington Square in North Beach and Fisherman's Wharf. In preparation, the tunnels were bored past Chinatown station, and the tunnel boring machines were extracted from the intersection of Powell and Columbus, near Washington Square. San Francisco Chronicle architecture critic John King wrote there was "a compelling power to the idea of an extension that, if nothing else, would make the Central Subway seem less like a boondoggle and more of a factor in the shaping of tomorrow’s city. The empty lot of the Pagoda was a starting point for dreams. Let’s see if it can become a starting point of something real as well." The SFMTA published a concept study in January 2015 on the feasibility of several options for phase 3. A conceptual fourth phase has been advanced by SFMTA and transit advocates to further extend the line west of Fisherman's Wharf to the Presidio.