Transbay Transit Center Construction Reaches Halfway Point

Transbay Transit Center

An aerial view of the Transbay Transit Center construction site, viewed from 201 Mission St. (Mark Andrew Boyer/KQED)

“No great thing is created suddenly.”

The quote, attributed to the Greek philosopher Epictetus, is splashed across plywood panels at Fremont and Mission streets in downtown San Francisco. It’s part of an ad campaign for the soon-to-be-built Salesforce Tower, but it could also apply to the neighboring Transbay Transit Center, the grand transportation terminal that has rendered a large chunk of SoMa a construction zone for the past several years.

Workers officially broke ground on the transit center in 2010, beginning with the demolition of the old Transbay Terminal. Nearly four years later, the site still looks like a 1,500-foot-long chasm, buttressed by dozens of huge steel tubes. But that will change soon. According to the Transbay Joint Powers Authority, construction is at about the halfway point. After two years of underground work, the above-ground portion of the building will begin to take shape this fall.

Last week, the TJPA conducted a tour of the construction site to show off its cavernous underground portion before vertical construction begins.

Transbay Transit Center

The walls are supported by a series of horizontal steel pipes, which are 3 feet in diameter. (Mark Andrew Boyer/KQED)

It’s difficult to get a sense for the scale of the project from street level, because all of the work up to this point has been underground. “You get your exercise,” said Chris Jones, who serves as the project’s quality assurance coordinator. “Basically, if I do my rounds, that’s one lap around the project. It’s half a mile.”

To give you an idea of just how big it is, two Transamerica Pyramids, laid down end to end, would nearly fit in the hole. During excavation, workers removed enough material to fill 120 Olympic swimming pools. (Other excavation trivia can be found here.)

The steel that will support the new building will come from seven fabrication shops that are spread out all over the country. “Our job numbers just came in, and I think we’re employing upwards of 6,000 people from around the country to create the steel,” said Stephanie Reichin, a spokeswoman for the TJPA.

Transbay Transit Center

“We’re employing upwards of 6,000 people from around the country to create the steel,” said TJPA spokeswoman Stephanie Reichin. (Mark Andrew Boyer/KQED)

The center’s $1.9 billion first phase will include a five-story bus terminal, which will stretch across four blocks. The building will be topped with a 5.4-acre rooftop park, which has been compared toNew York’s High Line. Future phases, which have yet to receive funding, will link high-speed rail and Caltrain to the station.

One of the biggest challenges associated with the site is groundwater. In the 1840s, the bay’s shoreline was roughly where First Street is today. So, when workers began to dig, they encountered a lot of water.

“We created, essentially, a bathtub,” said Reichin. That enabled workers to excavate the site without disrupting the surrounding water table. Crews pounded 100-foot-long I-beams into the ground, creating underground walls that are supported by a series of horizontal steel pipes, which are 3 feet in diameter. Those walls serve to prevent dirt and water from the surrounding neighborhood from pouring into the site.

Transbay Transit Center

Workers tour the lower levels of the Transbay Transit Center construction site. (Mark Andrew Boyer/KQED)

Workers found more than just water when excavating the site. They famously discovered a 1,300-year-old woolly mammoth tooth, some gold chips and a treasure trove of Gold Rush-era artifacts.

Recently, the transit center has been making headlines for its escalating price tag. Last month, the Chronicle reported that the project’s costs had risen by $150 million, forcing officials to drop more than $50 million in “cosmetic” expenses.

The enormous size of the building is an obvious contributor to the hefty price. But there are other reasons.

“We’re building it correctly,” said Reichin. “We have to build it for seismic structural integrity.”

The building must also conform to Federal Transit Administration and federal security requirements. The Bay Area’s recent construction boom is also to blame, enabling construction companies to take their pick of projects, driving up prices in the bidding process.

Standing at the base of the concrete chasm in a maze of scaffolding and rebar, it’s still pretty difficult to picture the curvy, metal-clad structure that will rise over the next three years. But construction is moving steadily forward. The first four decks of the lower concourse have been poured, and beginning this fall, the building will begin to take shape above ground.

Transbay Transit Center

Construction is expected to be complete in late 2017. (Mark Andrew Boyer/KQED)