San Francisco’s Transbay Transit Center: A New Approach

Cross Section of the Transbay Transit Center, courtesy of transbaycenter.org

San Francisco’s Transbay Transit Center is an ambitious project consisting of a train and bus terminal, several gigantic high rise buildings and an elevated park above the terminal. The Center will replace the current Transbay Terminal bus facility, a relic of streetcar service across the Bay Bridge. The current facility has low ceilings, low capacity and is seismically unsound. It is also unable to accept underground train platforms.

With the understanding that a new transit center is needed, several options were explored regarding the train box under the station. In the original plan for the center, the bus platforms were to be built first, opening in 2015, with the train platforms and subterranean mezzanine being built later, under the functioning transit center. Such a plan contains the obvious fallacy that building a massive train station under an operating building is massively expensive, especially when the building was not conceived in the first place to accept such underground facilities. This argument was one of the main reasons why a new transit center is being built in the first place.

A stroke of fate has enabled the designers of the Transbay Transit Center to change their approach from top-down to bottom-up. High speed rail money from the Federal Railroad Administration and the California High Speed Rail Authority (CAHSRA) is paying the 400 million dollar cost of installing the train box at the same time as the rest of the transit center. 400 million may be difficult to stomach for a train station, but given the status of infrastructure spending in the United States, leaving the train box for later would likely have been its death knell. Estimates for the future cost of a train box under the completed transit center were nearly double the cost. I applaud the Transbay Joint Powers Authority (TJPA) and its consultants for bringing together this funding and ensuring that the transit center will fulfill its potential.

The inclusion of the train box at the beginning of the project brings many issues with its design to the forefront of discussions on the transit center. The CAHSRA has required platform space to run trains at five minute frequencies. This requirement is ridiculous. Not even Japan’s Shinkansen High Speed Rail Service, the busiest in the world, runs at such frequencies. As you can see in the image above, this mandate by CAHSRA robs platform space and tracks from Caltrain. The current train box arrangement would only allocate Caltrain two tracks and one island platform, limiting capacity into the Transbay Transit Center to less than current peak hour headways on the line. Any future service increases to cope with the inevitable increase in ridership due to electrification and direct service to Downtown San Francisco could only run as far as the current 4th & King terminal due to capacity constraints at the Transbay Transit Center platforms. This artificial constraint would defeat much of the purpose of the Caltrain Downtown Extension Project to connect Caltrain to the Transbay Transit Center. The train box will fit six tracks and three island platforms. Instead of a 4/2 split in favor of CAHSRA, the spilt should be the oposite with Caltrain being allowed use of 4 tracks. The demand and frequency for Caltrain’s local service along the peninsula will be much higher at all times of day, hence it should have more track space.

Another concern I have with the current design of the Transbay Transit Center is the lack of coordinated planning between the TJPA and BART about a possible future BART station in or adjacent to the complex. The need for a second Transbay Tube is widely recognized and a station at the Transbay Transit Center would be ideal, permitting a direct connection between high speed rail, Caltrain and BART. Provisions for a BART station could include simple, low-cost fixtures like entrance bellmouths, locations for fare gates and a larger mezzanine to accommodate future BART riders to the transit center. Like the train box, these (relatively) inexpensive inclusions to the project would eliminate future costs and integrate a future rapid transit station into the transit center.

My final concern about the current iteration of the Transbay Transit Center project is the slow speed at which construction on adjacent development is proceeding. Over six high rise buildings are planned as part of the project and much of the revenue TJPA is counting on is from the sale of currently vacant land owned by the authority to developers. Many of these towers were supposed to have begun construction in 2009 or earlier this year. Obviously current economic conditions have depressed property values and made large real estate developments less attractive. Fortunately, the towers near the Transbay Transit Center are transit oriented development in its purest form, with no limits on density or height. Hopefully developers will acknowledge this fact and gamble that the market for housing in urban areas will rebound, otherwise a large chunk of TJPA’s revenue will be lost.

With a nod to the future the Transbay Transit Center has refocused its priorities and now will be built in a more cost effective and timely manner. Hopefully this forward looking strategy will be further adopted, designing the terminal to be BART-ready for the time when the second transbay tube will be built. Regardless of this outcome, the Transbay Transit Center will be one of the most exciting transit stations in the world, connecting all parts of the Bay Area to the rest of California and providing the massive, Grand Central Terminal-style transit station that the Bay Area has always lacked.

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About Karl Tingwald

Civil engineering student at the University of Southern California with a severe transportation compulsion.

Posted on June 4, 2010, in BART, San Francisco Bay Area, Transbay Transit Center and tagged , , , , , , , , , . Bookmark the permalink. 1 Comment.

  1. It’s a lot easier to reallocate 2 of the HSR tracks to CalTrain after they’re built (and underutilised) than not building them at all. Overcapacity tends to be much less troublesome than undercapacity (or not building at all).

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