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fter debating for numerous years behind closed doors, the Transbay Joint Powers Authority has decided to take down the last mile of Interstate 280 and replace it with a highway that can be connected to an electrified Caltrain and high-speed rail tracks.
Additionally, a part of the San Francisco Transbay Terminal project and largest project in the Prop K Expenditure Plan — the Transbay Joint Powers Authority’s California Downtown Extension (DTX) — will transform the San Francisco transportation system. The extension will be roughly 1.3 miles long, from Fourth and King Streets to the new Transbay Transit Center (TTC) and will include an underground tunnel, the creation of a neighborhood with 3,000 new homes and mixed-use of commercial development.
According to the Transbay fact sheet, the primary goals of the new DTX include improved access to rail and bus services, improved Caltrain service and other major transit companies, reduced motor vehicle use, reduced traffic congestion, improved air quality and support of local economic development goals.
Greg Riessen, the city planner who developed the idea, told the San Francisco Bay Guardian that the main goal of the new extension and high-speed rail is to elevate Interstate 280, better integrate the city’s Mission Bay and Potrero neighborhoods and decrease traffic.
“If you get the freeway out of the way, it’s a ton of space,” Riessen said. “The whole corridor of the freeway is blocking the ability to do anything else.”
The new extension will connect Caltrain, AC Transit, Golden Gate Transit and SF Muni, according to the Bay Alliance. Moreover, the DTX will be able to accommodate a new “blending system” in which the new high-speed rails will merge with the original Caltrain rails.
According to the Green Caltrain Bay Alliance blog, the new corridor will be able to handle up to six Caltrain trains per direction per hour, and up to four high-speed rail trains per direction per hour.
The program budget is estimated to be around $4.1 billion. In May 2010, the Transbay Joint Powers Authority (TJPA) acquired $1.6 billion for the first steps of the new DTX project, which includes pedestrian ramps, a train box and a high-speed rail station; the TJPA believes that the next steps will cost about an additional $2.5 billion.
However, a downside of the DTX includes its effect on a train’s ability to turn. The time for the high-speed rail to turn the opposite direction is roughly 15 to 20 minutes, in comparison to a BART train, which only takes five minutes.
The TJPA will be working to amend this aspect of the high speed rail trains. In addition, because of the development of the new Golden State Warriors arena, unaddressed traffic issues may be exacerbated with the introduction of the new Caltrain system.
“[The traffic] could drown the city, this tsunami of cars, particularly with all the development planned all the way down to Hunters Point,” former San Francisco Mayor Art Agnos told the Bay Guardian. “I like the idea, but we need a serious discussion of the details, particularly with all these development proposals.”
The DTX is scheduled for completion in June 2018. However, due to lack of funding, the project is currently on hold.
The TJPA, the city of San Francisco and other funding partners will work to support the first phrase of the project and to advance ideas to close the funding gap for the second phase with construction beginning in 2017.
