Cracked Beam Closes Month-Old Structure > ENGINEERING.com

The Transbay Transit Center, completed in August 2018, spans two major roadways. One of those spans was shut down after cracks were found in both of the span’s supporting beams. (Image courtesy of Transbay.)

The Transbay Transit Center, completed in August 2018, spans two major roadways. One of those spans was shut down after cracks were found in both of the span’s supporting beams. (Image courtesy of Transbay.)

The Transbay Transit Center is the pride and joy of San Francisco’s transit system. An innovative train/bus station featuring an organic façade and a rooftop garden, the center is also closed after being open to the public for less than a month, because of significant cracks in its support beams.

The Transbay Joint Powers Authority—the organization responsible for overseeing the center’s construction—is not yet sure why the support beams collapsed. It will be working with its primary contractor and the structural engineering firm that helped create the design to try to determine exactly what went wrong.

Until they return their verdict, here are some of the facts surrounding the building and the beams, and some of the reasons they might have cracked.

The Center is a $2.2 billion bus and train station, informally called “the Grand Central of the West.” The terminal is meant to serve 100,000 customers per weekday, in a facility that includes a bus deck, a train station and a 5.4-acre rooftop park. The terminal opened this past August after being under construction for nearly a decade, with workers breaking ground back in 2010.

The center stretches three blocks and passes over two major roads, with the spans supported by four 60-foot-long…

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