Central Subway

Central Subway tunnel at the 4th Street Portal

transparent spacer image Above: The completed tunnel at the portal at 4th St., under I-80. Below: The roof slab for the Chinatown station is now complete. Bottom: construction at Stockton and Market.
Chinatown station roof slab complete
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 $124 million in funds programmed by the Transportation Authority and $469.2 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 $849 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 have been completed, the Tunnels contract is substantially complete and in the closeout phase, 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 include 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. The Stations and Systems contract was awarded in May 2013 to Tutor Perini Corporation. The contract consists primarily of the four stations and their associated systems, including heating, ventilating, and air conditioning (HVAC), vertical transportation, and lighting. Other associated components include a connection between the existing Powell Street station and the new Union Square station, and installation of fare collection equipment at all new stations.


As of April 30, 2015, the Central Subway project was 49.75% complete. 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 have been completed, work is nearing completion on the Tunnels contract, and the focus has shifted to the Stations and Systems contracts.

On April 15 the $241.29 million tunnels contract reached substantial completion, on schedule and slightly under the baseline budget. Contract closeout and restoration activities will continue until June 2015, when final completion is expected. Reaching this major milestone means that one of the major risks of the project has been retired.

Tutor Perini, the contractor for the $838.24 million Stations and Systems contract, the largest single construction contract ever awarded by the SFMTA, is proceeding at all four station locations. At the Chinatown station, excavation for the surface level slab has been completed and concrete was placed on three-fourths of the station headhouse area. In addition, mass excavation is under way. At the Union Square station, work continues at the Union Square garage with installation of tiebacks in preparation for demolition, installation of I beams for the roof deck from Maiden Lane to the south side of Geary Street, and demolition of the BART annex on Ellis St. At the Yerba Buena/Moscone station, construction continues on the roof slab, where all roof slab segments on the west side have been completed. At the surface station at 4th and Brannan Streets, work was completed on the installation of the cast-in-place drilled piles. As of the end of April, this contract was 30.09% complete. Substantial completion of this contract is scheduled for February 2018. As of the end of April 2015, the contractor had spent 523,775 job hours without a reportable safety incident.

MTA 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 on 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.


Download the latest Central Subway Fact Sheet.


Date and Milestone

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