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Exclusive First Look at Transbay Transit Center Construction

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Long-armed excavator on bridge above work site [Photo by <a href="">Patricia Chang</a>]
Long-armed excavator on bridge above work site [Photo by Patricia Chang]

[Photo by Patricia Chang] In case you haven't heard, San Francisco's Transbay Transit Center is kind of a big deal. (Emphasis on big.) This massive bus and train station will nearly stretch from 2nd to Main streets, and will be 5 levels with a 5.4-acre rooftop park and surrounding plazas. It will be completely enveloped in glass perforated aluminum, and house all major regional bus lines, Caltrain, and maybe, eventually, possibly, California High-Speed Rail. We recently took tour of the site to find out just how big this project is.

We arrived near the eastern portion of the site, between Beale and Fremont streets, where excavation is just beginning. Workers have already installed a bridge over Fremont Street to allow for excavation under the street. They're in the process of installing a trestle bridge that will allow cranes and excavators to roll over the top of the site, removing mountains of dirt and debris (to find some really cool stuff), and lowering in temporary supports to maintain the structural integrity of the pit until concrete can be poured.

As we traveled west toward 2nd Street, where the first days of construction began, the depth and scale began to increase dramatically. We eventually found ourselves 65 feet below street level, looking up at the towers surrounding us. Workers at this end have completed excavation and ground stabilizing, and are currently testing out the waterproofing that will eventually turn the entire site into a giant bathtub. The next step for the site will be pouring the 6+ feet thick foundation. 3000-4000 cubic yards of concrete will be poured at a time (that's 300-400 trucks per pour) in what we can assume will be chaotic overnight sessions.

When the first phase is completed in late-2017, the entire above ground building will be completed, along with the "train-box" in the lowest level of the station, and the all bus ramps, a bus storage facility, and the landscaping of parks/plazas. Phase 2, which does not have a definitive start date at this point, will involve outfitting the train-box for passenger service and digging a tunnel from the current Caltrain depot at 4th and King streets to the terminal itself.
· Skin Deep: Changes to the Transbay Transit Center Design Reflect Budgetary Realities [Curbed SF]
· Transbay Transit Center Project Digs Up Woolly Mammoth Tooth and Jaw [Curbed SF]
· Transit Center Video Reveals Stuff We Know About, in Sexy Detail! [Curbed SF]
· Transbay Transit Center [Homepage]