Central Subway

Mining of the Chinatown station

transparent spacer image Above: The completed tunnel at the portal at 4th St., under I-80. Below: Excavation of the Yerba Buena/Moscone Station has reached the invert. Bottom: construction at Stockton and Market.
Yerba Buena Moscone Station Construction
Market Union Square station construction


The Central Subway is the second phase of the Third Street Light Rail line, which opened in 2007. The Central Subway will extend this line northward from its current terminus at 4th and King Streets to a surface station south of Bryant Street and go underground at a portal under I-80. From there it will continue north to stations at Moscone Center, Union Square—where it will provide passenger connections to the existing Powell Street BART and Muni Station— and at Chinatown, where the line will terminate. The Central Subway is expected to carry nearly 73,000 passengers a day, making it the second most utilized rail project in the Federal New Starts Program. On March 30, 2010 the Transportation Authority Board adopted a Baseline Budget, Schedule and Funding Plan for the project. Revenue service is scheduled for late 2018. The total project budget is $1.58 billion, and the San Francisco Municipal Transportation Agency (SFMTA) has full funding commitments from a combination of local, state, and federal sources. The primary funding source for the Central Subway is the federal New Starts program. To date, the project has received $140.5 million in funds programmed by the Transportation Authority (including $124 million in Prop K funds) and $769 million in federal New Starts funds. It also received $61.3 million in Prop 1A High Speed Rail connectivity funds. On October 11, 2012, the SFMTA received the Central Subway project’s Full Funding Grant Agreement (FFGA), from the Federal Transit Administration (FTA), the most significant funding-related milestone in the New Starts process The FFGA represents the FTA’s official commitment of the $942 million in federal New Starts funds to the project, a major milestone that allowed the project to move forward into the main construction phase.

Final Design was completed in October 2012. It was delivered under three contracts: DP1-Tunnels, DP2-Stations, and DP3-Systems. The project is being delivered in four construction packages, all of which have been awarded: Utility Relocation 1, Utility Relocation 2, Tunnels, and Stations and Systems. Both utility relocation contracts and the Tunnels contract have been completed, and work is underway on the Stations and Systems contract.

The Tunnels contract was awarded in June 2011, to the Joint Venture of Barnard/Impregilo/Healy. The $233.9 million contract consisted of 1.5 miles of twin-bore tunnels underneath Fourth Street and Stockton Street, from I-80 to North Beach. Its major components included tunnel boring machine (TBM) procurement, construction of the TBM launch box and cross passages, construction of extraction shaft and portal, and headwalls for the Union Square and Moscone stations, among other elements. The contractor procured the TBMs from The Robbins Company, headquartered in Solon, Ohio. With the completion of this contract in May 2015, on schedule and $16 million under the baseline budget, the Central Subway project achieved a major milestone. Reaching this milestone retired one of the major risks of the project.The Stations and Systems contract was awarded in May 2013 to Tutor Perini Corporation. At $838 million, this is the largest single construction contract ever awarded by the SFMTA. The contract consists primarily of the three underground stations, one surface station and the project-wide systems, which include track, overhead contact system, communications, signals, ventilation, and fire protection among others. Other associated components include a connection between the existing Powell Street station and the new Union Square station.




As of January 31, 2017, the Central Subway Project was 65% complete. At the Chinatown Station, the headhouse has been mostly excavated and mining of the station cavern is underway. PG&E work on Stockton and Washington Streets has been completed. At the Union Square station, work continues in excavation and shoring of the station box and at the station headhouse on the Union Square garage. Meanwhile, at the Yerba Buena/Moscone station, excavation has reached the invert and the tunnel liners have been removed within the station box. After installing the rat slab and waterproofing, rebar is being installed for the five-foot-thick invert slab. For the surface station at 4th and Brannan Streets and Systems package, work has been completed on the special trackwork at 4th and King Streets, the 78 in. sewer reconstruction and the 48 in. sewer installation. Ductbank and pavement renovation is also underway.As of January 2017, the Stations and Systems contract was 54% complete, with substantial completion anticipated by February 2019.

The SFMTA continues with its construction outreach program, keeping the neighbors in the vicinity of the project informed about ongoing and upcoming construction activities, lane closures, and general project information. Transportation Authority staff and project delivery oversight consultants will continue to work closely with the SFMTA project team as the project progresses the construction phase. Revenue service is scheduled for December 26, 2018.


  • Extend the north-south corridor of Muni's Metro System
  • Provide shorter travel times for passengers
  • Relieve congestion on the Stockton Street corridor
  • Provide connectivity to a future Geary line.


Date and Milestone

Conceptual and Preliminary engineering: Oct 2003–Dec 2009
Supplemental engineering: Jul 2005–Oct 2008
FTA Record of Decision: Nov 2008
Final Design: Jan 2010–Oct 2012
Full Funding Grant Agreement: Oct 2012
Right of Way Acquisition: July 2009–Dec 2012
Construction: Jan 2010–Feb 2019
Startup and Commissioning: Mar 2018–Sep 2019
Revenue Service: Sep 2019 


Download the latest Central Subway Fact Sheet.