UPDATE: September 27, 2018: The Transbay Joint Powers Authority on Wednesday announced that inspectors found a second cracked steel beam at the Salesforce (Transbay) Transit Center, this one adjacent to the member that crews initially identified on Tuesday as having a fissure. The authority said it will carry out ultrasonic testing in order to determine how much damage there is. Nevertheless, the authority has authorized a shoring plan that will relieve stress on the structural steel in that area and, hopefully, prevent additional damage.

As soon as it is safe to do so, the authority will re-open the center and then make permanent repairs; however, it doesn’t anticipate commuters being able to use the center until at least the end of next week.

The authority said inspections at other areas of the transit center have not revealed any similar problems.  

According to a report from the San Francisco Chronicle, Skanska USA Civil West performed the steel work under a $189 million contract but sued general contractor Webcor/Obayashi for the cost of extra work resulting from construction documents that were "substantially defective and incomplete."

More than a dozen manufacturers made steel for the project, but, according to the Chronicle, the beams with cracks were produced by Stockton, California-based Herrick Corp. Both cracks are in 60-foot beams, and the first fissure runs 2.5 feet from side to side and four inches from bottom to top but reportedly is not located in the main section of the beam.

Dive Brief:

• The Transbay Joint Powers Authority, the agency that oversees the $2.2 billion Salesforce (Transbay) Transit Center, announced a temporary shutdown of the facility on Tuesday after workers discovered a cracked steel beam in the ceiling of the third-level bus deck. The new center opened last month.
• The structural member, which is described as having a major crack or fissure, is part of the support system for the 5.4-acre rooftop garden and park, which includes, according to the San Francisco Chronicle, a 5- to 6-foot layer of soil. The authority said it made the decision to close transportation hub "out of an abundance of caution" after speaking with engineers and contractors. The project's construction manager and general contractor Webcor/Obayashi, along with structural engineer Thornton Tomasetti, will determine the cause of the crack and repair the beam and will also inspect the rest of the building's steel beams.
• “The safety of everyone who visits the Salesforce Transit Center is our obligation and highest priority,” Mark Zabaneh, executive director of the authority, said in the announcement. “While this appears to be a localized issue and we have no information that suggests it is widespread, it is our duty to confirm this before we allow public access to the facility.” Commuters will use the old transit center while crews work to ensure the safety of the new center.

Dive Insight:

Until inspections are complete, there's no way to know the cause of the crack. Possibilities include a production error, a flaw in the original structural design or incorrect installation, but at this point it's all speculation. Adding to the mystery, however, is a report from the Chronicle earlier this month that the footpath that encircles the center's rooftop park is already crumbling and has developed "the walking equivalent of potholes." The park cost more than $32 million to build, and the walkway's price tag was $673,000.

The transit center's troubles have taken the spotlight, for now, off of one of its infamous neighbors, the Millennium Tower. The luxury condominium high-rise, which opened its doors to residents nearly a decade ago, has sunken about 18 inches so far and is leaning approximately 6 inches at the top. Residents have demanded a fix, but the one proposal that could be the most feasible — anchoring the building into bedrock — would cost an estimated $500 million. The latest problem with the Millennium is a window crack at the 36th floor, which could signal additional structural issues. Inspectors are still investigating potential causes.