SAN FRANCISCO (CBS SF) -- San Francisco's new $2.2 billion Salesforce Transit Center -- heralded as the 'Grand Central of the West' -- will remain closed until at least next week after a second steel beam showed signs of cracking, though not as severe as a cracked beam discovered on Tuesday.
In a press conference Wednesday afternoon, Executive director Mark Zabaneh described the cracks as localized, and not evident in similar elements throughout the building.
"Our inspection last night indicated that an adjacent beam to the beam in question also suffered some cracking," he said. "Not to the same extent as the beam in question but still has some cracking," he told reporters.
Zabaneh said engineers have looked at the similar pieces and determined them to be okay.
"We don't know what the cause of the crack is at this point," said Zabaneh. "There may be three possibilities -- fabrication, installation and design."
Two San Francisco engineers say it's too early to point to a likely cause, but they say investigators will look at the beam's U.S. manufacturers, building's design and installation process.
Engineer David Friedman says the beams were likely delivered and installed without the crack two years ago, but the flaws appeared once they started supporting a rooftop garden and other loads.
Engineer Joe Maffei says the cracks could have been caused during installation, perhaps by quickly rising and falling temperatures caused by a welding torch.
David Bonowitz is a licensed structural engineer with 25 years of experience.
He says for any building to work, a lot of things have to work in concert. A problem with any single aspect could spell trouble.
"You can have a good design, but if the material is flawed that could end up turning into damage. You can have a good design properly built, but you get a load you didn't expect, that becomes damage," said Bonowitz.
As of Wednesday, the Joint Powers Authority outlined a three-step plan to get the transit center functional again. The plan includes shoring up Fremont Street before moving on to the cracked beams to get buses up and running again and finishing the project with the permanent fix.
However Bonowitz says just repairing the cracks without knowing the cause is like throwing penicillin at an illness without knowing the specific disease.
"If there is a crack or a damaged structural member, that's going to have to be either repaired in place or removed and replaced," said Bonowitz. "But that doesn't answer the question. Before you go about repairing something that's just going to be damaged again, you want to make sure what actually happened. That's going to take some time."
San Francisco Mayor London Breed took a tour of the terminal to see first hand the cracked beam -- built by Central Valley metal fabricator Herrick Corporation -- that was discovered Tuesday afternoon, forcing the closure of the facility that handles commuter buses coming from inside and outside the city.
"As the safety of the people of San Francisco is always of primary importance, we will continue to act cautiously and keep the Transit Center and block of Fremont Street closed until we have further answers," Breed posted on her Twitter account.
She further said that an investigation needs to launch immediately to determine how such a beam failure could have happened in a building that only opened last month.
"Someone needs to be held accountable once the cause is determined," Breed tweeted.
Zabaneh said workers discovered the crack early Tuesday while installing roofing tiles. He told reporters the crack appeared to be localized to one of the three buildings located on Fremont St.
"We are looking at other areas to make sure there are no other issues with the transit center," he said. "At this time, all indications are this is localized on Fremont St."
Enveloped in wavy white sheets of metal veil, the five-level center includes a bus deck, a towering sky-lit central entrance hall and a rooftop park with an outdoor amphitheater. Zabaneh said American steel was used in the center's construction.
According to Zabaneh, the beam was last inspected when it was first installed last year.
"It's very disappointing that we have to inconvenience the public but it's a safety issue and we take it very seriously. We can't take any chances," Zabaneh said. "We felt, out of an abundance of caution, that we should close the transit center and we're attempting to determine the cause of the crack and the measure we need to take to fix it."
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