The Portal, also known as the Downtown Rail Extension (DTX) project, will extend Caltrain service from Fourth and King Street to the multimodal Salesforce Transit Center, in the heart of downtown San Francisco and deliver the California High-Speed Rail Authority’s future high-speed rail service to the Bay Area.  It is a transformational, once-in-a-generation investment that will ultimately connect 11 transit systems from the Bay Area and Southern California.

Delivering the portal

A Key Regional Rail Connection 

The 1.3-mile rail extension (1.95 miles of total construction length) will be constructed principally below grade using cut-and-cover and mined tunneling methods underneath Townsend and Second Streets. The project includes an underground station at Fourth and Townsend Streets along with the Salesforce Transit Center's basement levels, six structures for emergency exit, and ventilation along the alignment, utility relocation, and rail systems work.

DTX Alignment Map.


Fourth and Townsend Street Station

The new underground station at Fourth and Townsend Streets will serve Caltrain commuters. The station entrances along the north and south sides of Townsend Street will lead to two levels below grade: a concourse mezzanine and a train platform. The concourse will accommodate passenger amenities such as ticketing; maps and schedule information; and restrooms. It will also house mechanical and electrical rooms and Caltrain staff areas. The Train Platform will feature a center platform with one passing track on the south side.



Transit Center Station

The already built two-level trainbox will serve as the Lower Concourse, and Train Platform levels when The Portal is complete.

The Lower Concourse will house rail ticketing, passenger waiting areas, and support spaces. At its east end, it will connect to the intercity bus terminal and a pedestrian tunnel leading to the Embarcadero BART/Muni station, approximately one block north of the Transit Center. Along with ticketing and passenger waiting areas for rail and support spaces, the Lower Concourse will contain retail space.

The Train Platform will contain six tracks and three platforms for Caltrain commuter and high-speed rail service. Back-of-house support spaces will also be built on the Train Platform level to support rail service.

Regional Collaboration

The TJPA is leading the delivery of The Portal in cooperation with five other agencies through the San Francisco Peninsula Rail Program
Memorandum of Understanding, a regional collaboration model to formally deliver the project.

the portal rail Operators


Caltrain already serves as a vital regional link by connecting San Francisco to the Peninsula, Silicon Valley, and San Jose, but it currently ends 1.3 miles from downtown San Francisco. The Portal will extend the Caltrain rail line into the new Transit Center, the heart of San Francisco’s new downtown. Extending Caltrain into downtown will directly save commuters almost an hour a day in travel time, and will result in less driving and more people taking the train into the City from the Peninsula. 


High Speed Rail Authority


The Portal will accommodate California’s High-Speed Rail service, which will connect the mega-regions of the state, and contribute to economic development and a cleaner environment. The California High-Speed Rail Authority estimates that the system will run from the Salesforce Transit Center in San Francisco to the Los Angeles basin in under three hours. 

learn more about the HSRA