The approximately $6 billion Transbay Transit Center/Caltrain Downtown Extension (TTC/DTX) project in San Francisco consists of following three interconnected elements. A replacement of the the outmoded Transbay Terminal at First and Mission streets with a modern terminal (Phase 1).The  extending of the underground Caltrain 2.09 km (1.3 miles) from current terminus Fourth and King streets to the new TTC at First and Mission streets, with accommodations for future high-speed rail service (Phase 2). The creation of a new transit-friendly neighbourhood with 3,000 new homes  and mixed-use commercial development.

The new modern regional transit hub will connect the eight Bay Area counties and the State of California through 11 transit systems: AC Transit, BART, Caltrain, Golden Gate Transit, Greyhound, Muni, SamTrans, WestCAT Lynx, Amtrak, Paratransit and future High Speed Rail from San Francisco to Los Angeles/Anaheim.

The Phase 1, should be done by December 2017, and will need funding  of an additional 2.5 million, and it will be completed by mid June.

The Phase 2 of the project, named the Downtown Rail Extension (DTX), will include a new intercity bus facility and the completion of the Transit Centre’s train station with a pedestrian connection to BART and Muni. It is expected to be completed by 2029. TJPA’s current costing estimate for Phase 2 (DTX) is $3.9 billion.

The 2.09 km rail extension will be constructed principally below grade using cut-and-cover and mined tunnelling methods underneath Townsend and Second Streets. The project includes an underground station at Fourth and Townsend streets, six structures for emergency exits, and ventilation along the alignment, utility relocation and rail systems works. A team led by Parsons Transportation Group has substantially completed work on preliminary engineering of Phase 2.

The route Caltrain and high-speed rail will take place once they enter San Francisco but this has yet to be decided  between the Mission Bay alignment or the Pennsylvania Street alignment. The Mission Bay alignment would go past the Warriors Arena and the AT&T Park onto 2nd Street and finish at the Transit Centre. The Pennsylvania Street alignment would go past the Potrero Hill neighbourhood past China basin and the existing  4th and King train yard making a left on 2nd Street and finally to the Transit Centre. The selection will depend on the cost of each alignment. City Hall and its supervisors will decide which alignment will better serve San Francisco.For further information click here and here. Visit http://www.sfcta.org/transbay-transit-center and http://tjpa.org/project/downtown-rail-extension. 15/18.