SPUR’s report Critical Cooling recommends 42 options for reducing local carbon emissions. This is one of them. To learn about all 42 ideas, read the full report

Build the Transbay Transit Center/Downtown extension of Caltrain

Urbanist Article
Annual savings potential:
Annual public cost:
Public cost per ton:
Implementing agency:

Horizon year:
28,200 tons
Transbay Joint Powers Authority, Caltrain Joint Powers Board


  • Construction of the Transbay Transit Center and Caltrain extensions will add an additional 10,000 daily transit trips in the Caltrain corridor, most of which will be diverted from auto travel
  • There will be an annual reduction of 78 million VMT in the Caltrain corridor
  • Even with an increase in required propulsion energy for trains, there will be a net decrease of 28,100 tons of CO2 emissions from the transit improvements
  • Our analysis excludes the emissions associated with construction, which can be significant in the case of large infrastructure projects


Construction of the Transbay Transit Center and Caltrain Extension would move Caltrain service (and California High Speed Rail) closer to San Francisco’s downtown, and it would create a state-of-the-art transfer facility for buses and trains in the Financial District. By improving transit connections, the project will encourage some drivers to choose transit, reducing regional emissions. As with other transit projects, the high capital costs of the project mean that it cannot be justified on the basis of emissions abatement alone. However, emissions abatement is an important co-benefit to consider alongside other impacts of the project.

Relative Impact
There are will be 145.93 million daily vehicle miles traveled in the Caltrain corridor by 2030, generating approximately 15.54 million metric tons of CO2 emissions per year.1

What we do now
Caltrain tracks terminate at Fourth and King streets in the South of Market Area, well outside the Financial District. The nearby Transbay Terminal serves as a destination and transfer point for trans bay buses.

What we could do
The construction of the Transbay Transit Center includes three related projects: The construction of a new transfer center to replace the existing Transbay Terminal between Mission and Howard streets, northeast of Second Street. Caltrain will be extended 1.3 miles to the new site. The redevelopment area around the site will be upzoned to permit new transit-oriented development, including 3,400 residential units, 1.2 million square freet of office space and 60,000 square feet of retail space. The terminal itself will be part of a very large new tower office building, which will be built by Pelli Clarke Pelli Architects as chosen through a design and development competition in May 2008. The extension will improve the convenience of Caltrain to downtown San Francisco, and improve the connectivity of regional transit systems. California High Speed Rail, recently approved by California voters, will utilize the Caltrain right-of-way. If the extension is built, High Speed Rail will serve the new terminal.

Cost and cost components
The Transbay Joint Powers Authority’s most recent cost estimates place the capital cost for the extension at approximately $3 billion. According to the project’s final environmental impact statement, it also will generate significant revenue that will help to offset the cost somewhat. Revenue includes $140.2 million in net new operating revenue; $287.9 million in land sales; $50.2 million from a leveraged lease transaction; and $534.2 million from tax increment financing. The remaining capital cost, financed at 5 percent over 50 years, would yield an annualized cost of $108.87 million.

Carbon savings potential
Construction of the Transbay Transit Center and Caltrain extensions will improve the convenience of travel by Caltrain, adding an estimated 10,000 daily transit trips in the Caltrain corridor by 2030, about 80 percent of which will be diverted from auto travel. The final environmental impact statement estimates that the project will lead to a reduction of 260,000 vehicle miles traveled per day.2 The estimated annual reduction will be 78 million VMT in the Caltrain corridor. Required new propulsion systems will create just 515 metric tons per year of new emissions, and the net annual emissions reduction will be 28,200 tons per year. The cost per ton of emissions abatement will be $3,861.

1 Final EIS/EIR Transbay Terminal/Caltrain Downtown Extension/Redevelopment Project http://www.transbaycenter.org/TransBay/content.aspx?id=114
2 Ibid