Can Downtown Extension to Transbay be built by 2022?

At Thursday’s board meeting of the Tranbay Joint Powers Authority, the Transbay staff presented a proposal intended to connect the Caltrain tracks to the Transbay terminal by 2022 – two years ahead and half a billion dollars below current expectation – by creating a Public Private Partnership that would toll Caltrain riders ~$1.25 for the last stop to the financial district, and maintain the tunnel.

The board discussion raised many questions with the proposal.   Board member Reiskin and an SFCTA representative noted that the funding in the proposal includes multiple items that aren’t yet confirmed, including:

DTX funding proposal



Another question raised by board members Metcalf and Kim concerned the alignment of the tunnel.  The city and others have raised questions about the efficiency of the stairstep design.   The City of San Francisco is commissioning a study, to start early next year, to look at alternative alignments that would also extend the tunnel further down the corridor, enabling grade separation of the highly congested 16th street interchange and potentially facilitating a project to take down the end of the 280 freeway in order to use the land underneath to extend San Francisco neighborhoods.

Yet another concern regarded the capacity of the Transbay station.  How will Caltrain and High Speed Rail’s current plans to have separate platforms affect the number of trains that Transbay can serve?  The San Francisco study will also explore capacity scenarios.

DTX alignment

The proposal did include an additional structure intended to facilitate a later extension of a tunnel to grade-separate 16th and 7th.    However, Mayor Lee’s Transportation policy leader Gillian Gillett raised concerns that this structure, and a ventilation shaft in the proposal would not be compatible with the city’s plans to develop real estate at the 4th and King railyards; the tunnel structure couldn’t support a building above, and the ventilation shaft would occupy an otherwise prime building location.

Head start on extending tunnel

The time savings, according to the presentation, would come from the private partner’s motivation to get the project done quickly to reduce their cost of capital, and the money savings would come from lower contingency fees and greater overall efficiency. The time and money savings would make up for project delays from the 2020 date projected in 2008, and budget increases for additional grade separation at 16th and 7th, contribution to reconfiguring the 4th and King railyard, extending the train box for longer trains, and a few other changes.

Board members asked for more information and discussion about the risks of the public private partnership approach in addition to potential benefits.    After hearing this presentation, the board plans to spend the next several meetings drilling down into various aspects of the proposal.

Board members also asked about how the proposal for the Transbay operator to toll passengers would work with the operations of Caltrain and High Speed Rail.    The last slide in the presentation proposed exploring an option to create a contract not only to Design-Build-Finance-Maintain the tunnel but to Design-Build-Finance-Operate-Maintain, including the potential for a joint venture with Caltrain and/or High Speed Rail.   This sort of contract would be much larger  in scope, and a major change for how Caltrain is run.

In his comments, Muni Executive Director and Transbay Board Member Reiskin said that “there is no bigger transportation project for San Francisco than getting this built.”    The staff presentation highlighted why the project is so critical – there are 180,000 jobs within ½ mile of Transbay, and the project is forcast to increase Caltrain riders into San Francisco by more than 50%

The staff presentation and board discussion surfaced many important questions about how the Downtown Extension will be financed and built, and how the rail service will be managed in the age of electrification, DTX and the blended system. In the coming months there will be important conversations and debates about how the rail line will be extended downtown, how it will be paid for, and how the overall system will be managed.