Transbay Transit Center and Caltrain Downtown Extension

Transbay Transit Center west end steel erection

Rooftop park amphitheater rendering

Project Overview

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 $4.5 billion in year-of-expenditure dollars. In May 2010, the Transbay Joint Powers Authority (TJPA) Board adopted a $1.60 billion 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. On July 11, 2013, the TJPA Board approved a revised budget of $1.899 billion for Phase 1 of the project. This revision was to respond to drastically changed market conditions, modifications necessitated by an updated Risk and Vulnerability Assessment, and resetting contingencies and program reserve at prudent levels. The TJPA has developed a strategy to secure the additional funds needed to cover the cost increase. The current estimate for Phase 2 (DTX) is $2.6 billion.

This is the largest project in the Prop K Expenditure Plan, which designates up to $270 million (in 2003 dollars) for this purpose. 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 $174.3 million in Prop K funds to the project, in addition to state Regional Improvement Program (RIP) funds.  The Transportation Authority has also allocated $6 million in One Bay Area Grant (OBAG) funds toward bicycle and pedestrian improvements associated with the TTC.

Project Goals

  • 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.


vehicle and bus ramps exit areaSignificant progress continues to be made on Phase 1. Final Design was completed in May 2014 by a team led by Pelli Clark Pelli Architects. A team headed by Webcor Builders is providing construction management/general contractor services. Construction of the Temporary Terminal was completed in mid-2010 and full operations commenced at the new site on December 11, 2010. The contract with Balfour Beatty for construction of the buttress, excavation and shoring systems, reached substantial completion in May 2014. Shimmick Construction, the contractor for the construction of the below-grade structure, has completed all of the third-lift walls in the central and west zones, the second lift wall in the eastern zone, and the Lower Concourse deck.

Meanwhile, erection of the steel superstructure is under way and fabrication of steel members for the superstructure continues, with 302 out of 304 cast nodes delivered. The contractor bridged First Street with the steel superstructure in April 2015.  On the Concrete superstructure contract, work is proceeding with the fourth-lift walls in the west and central zones. Work has also commenced on the plumbing and HVAC contracts.

Construction of the dedicated bus ramps from I-80 to the terminal is currently focused on column work. All the viaduct piles have been completed, and completion of the pile cap that will support the cable-stayed section of the ramp has also been completed. Construction of the entire TTC facility is expected to be complete by late 2016.

Bus operations in the new Transbay Transit Center are scheduled to start in August 2017.


A team led by Parsons Transportation Group has substantially completed work on preliminary engineering of Phase 2. The DTX was originally scheduled for completion in 2019; however, work is on hold due to a significant funding gap. However, work continues on the Supplemental EIS/EIR and coordination with Caltrain and the California High Speed Rail Authority.

In 2012, the Metropolitan Transportation Commission (MTC) identified DTX as only one of two new regional priorities for New Starts funds in Plan Bay Area, the Regional Transportation Plan/Sustainable Communities Strategy that MTC adopted in July 2013. The regional endorsement of DTX helps to position the project well to receive federal funding in the highly competitive federal New Starts program.

TJPA is exploring the feasibility of alternative project delivery options, including Public Private Partnership (P3) as means to reduce cost and accelerate delivery. Authority staff will continue to work closely with TJPA, the City, and other funding partners to support delivery of Phase 1 and to advance strategies to close the funding gap for Phase 2.

Project Schedule

TIMEFRAMEspacer image
Jun 1995–Mar2001   Planning/Conceptual Engineering
Jun 2000–Jun 2009   Environmental Studies
Jul 2004–Sep 2009   Right of Way Acquisition
Jul 2007–Jun 2012   Design Engineering
August 2010   Operations begin at Temporary Terminal
August 2010   Demolition of old terminal begins
December 2010   Shoring Wall and Buttress construction begins
February 2013   Sub-surface construction begins
November 2014   Structural Steel construction begins
April 2015   Exterior Enclosure construction begins
April 2015   Interior Finishes begin
October 2017   Bus Operations begin