SF Transbay Transit Center Cracks Isolated to Beams, Say Experts

Phil Matier and Andy Ross report that an investigation into problems with San Francisco’s Transbay Transit Center have turned the focus onto construction materials and not the design of the facility:

That’s good news for the troubled transit hub. A design flaw might have meant the beams couldn’t support the weight of the building’s bus deck and three-block-long roof garden, and required a major redesign that could have shuttered the center indefinitely.

The center was closed down in September after cracks were found in a pair of support beams. Since then, experts have been working to determine the cause of the cracks, which were not found in other girders.  

“While [Mike] Engelhardt said it’s too early to draw conclusions, he described the cracks as ‘brittle fractures’ typically caused by either bad steel, a rough spot or other welding defect, combined with high stress levels in the affected area,” say Matier and Ross.

The beams have been removed and sent out for analysis. Transit officials say they do not want to jump to conclusions before the additional testing is complete and, for now, they are waiting to hear about possible repair strategies. The Transbay Transit Center will likely be closed for months while any necessary repairs are made.