The temporary facility will serve bus passengers while the Transbay Transit Center is being built, according to the Transbay Joint Powers Authority.
The center is scheduled to be completed in 2014, and will serve as a hub for bus and train service, including the California High Speed Rail to Los Angeles.
Officials estimate the center will serve about 100,000 passengers each day.
Today's groundbreaking takes place at 11 a.m. at the Temporary Terminal site at Beale and Howard streets.
