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Transbay Transit Center and Caltrain Downtown Extension

SalesForce Transit Center

Rooftop park amphitheater rendering


The Transbay Transit Center/Caltrain Downtown Extension (TTC/DTX) project will transform downtown San Francisco and regional transportation well into the 21st Century. The project consists of three interconnected elements: replacing the outmoded terminal with a modern terminal; extending Caltrain 1.3 miles from Fourth and King streets to the new TTC at First and Mission streets, with accommodations for future high-speed rail service; and creating a new transit-friendly neighborhood with 3,000 new homes (35 percent of which will be affordable) and mixed-use commercial development.

The total program budget is currently estimated at $6.2 billion in year-of-expenditure dollars. In June 2016, the Transbay Joint Powers Authority (TJPA) Board adopted a $2.26 billion revised budget for Phase 1, which consists of the TTC, bus and pedestrian ramps, and the train box, which is the underground portion of the TTC building that will house the Caltrain and high-speed rail station. This revision came as a result of a risk analysis refresh conducted in September 2015 that updated the risk model, and a Cost Review conducted by the Metropolitan Transportation Commission (MTC) also completed in September 2015. TJPA’s current estimate for Phase 2 (DTX) is $3.9 billion. 

This is the largest project in the Prop K Expenditure Plan. The Expenditure Plan specifies that the TTC and the DTX are to be built as a single integrated project. To date, the Transportation Authority has allocated $205 million in Prop K funds to the project, in addition to $16 million in state and federal funds. This includes $6 million in One Bay Area Grant funds toward bicycle and pedestrian improvements associated with the TTC.


  • Improved access to rail and bus services
  • Improved Caltrain service by providing direct access to downtown San Francisco
  • Enhanced connectivity between Caltrain and other major transit providers
  • Modernization of the Transbay Terminal that meets future transit needs
  • Reduced non-transit vehicle use
  • Accommodating projected growth in travel demand in the San Jose-San Francisco corridor
  • Reduced traffic congestion on US Highway 101 and I-280 between San Jose and San Francisco and reduced vehicle hours of delay on major freeways in the Peninsula corridor
  • Provide connectivity to a future Geary line
  • Improved regional air quality by reducing auto emissions
  • Direct access to downtown San Francisco for future intercity and high-speed rail service
  • Alleviation of blight and revitalization of the Transbay Terminal Area
  • Support of local economic development goals.


The new transbay transit center, named the Salesforce Transit Center, is now open for public use. It replaces the seismically deficient Transbay Terminal with a modern regional transportation hub connecting transit systems throughout the Bay Area. The transit center features a 5.4-acre rooftop public park, a public art program and 100,000 square feet of shopping and dining.

MUNI began full operations out of the Bus Plaza at street level in June. On August 12, 2018, AC Transit commenced inaugural service from the Salesforce Transit Center’s Bus Deck which connects directly to the Bay Bridge via a dedicated aerial bus ramp. Other regional transit agencies, including Amtrak, Greyhound, Westcat Lynx, and the MUNI Treasure Island will also provide service from the Bus Deck.

The basement of the Sales Force Transit Center will be the terminal station for Caltrain once it is extended from its current location at Fourth and King streets. It will also be the northern terminus for California’s High-Speed Rail system.


Caltrain DTX

With Phase 1 wrapping up, the TJPA has  shifted its focus toward Phase 2, the DTX.  The project is in the early design phase and  faces a significant funding gap. The TJPA has been working with the Transportation  Authority, City agencies and other funding  partners to build consensus on the DTX  alignment, identify ways to lower costs,  evaluate construction methods to reduce  construction impacts, and develop a funding   strategy to move the project forward.

At the direction of the Transportation  Authority Board, staff assembled an expert  panel to conduct a peer review of three    operational analyses related to the DTX with  the goal of helping policymakers decide whether the DTX should have two or three tracks as it approaches the Salesforce Transit Center. The panel presented its findings in April 2018, which unanimously concluded that three tunnel tracks are required to provide reliable and dependable service into the Salesforce Transit Center. Prop K sales tax also funded the Tunnel Options Study, which evaluated different construction methodologies to minimize cut-an-cover along the DTX alignment in recognition of the impacts this has on local businesses and street activity in the construction zone.

In July, the Transportation Authority Board approved $9.7 million in Prop K sales tax funds for the TJPA’s to advance design toward 30% for the DTX. The funding also supports follow-up to the Tunnel Options Study, value engineering and the development of a bottoms-up cost estimate. TJPA is managing the Parsons Transportation Group-led consultant team that is working on design. TJPA anticipates reaching 30% design in fall 2019.

DTX is one of only two new regional priorities for federal New Starts funds in Plan Bay Area, the Regional Transportation Plan/Sustainable Communities Strategy that MTC adopted in July 2017. This designation also contributed to the MTC’s support for the inclusion of $325 million for DTX in the Regional Measure 3 (bridge tolls) expenditure plan approved by Bay Area voters in June 2018.


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Aug 2010   Demolition of old terminal begins
Aug 2018   Bus Operations begin


Construction update photo courtesy Rocor via flickr Commons.