"The proposed station would not be large enough to accommodate half the passengers expected to be using the system by 2030. In addition, the current scheme poses engineering challenges for a Caltrain extension to the Transbay Terminal downtown, officials said."
"The problems have transportation officials scrambling to find fixes to assure that the rail projects don't miss out on federal stimulus funds."
"As it stands, the first phase of the project would be built without a "train box," the skeleton of the underground train station. The idea is to build it later, when funding becomes available. But building the train box in the first phase could shave an estimated $100 million off the $490 million cost."
"The Transbay Joint Powers Authority board must decide by summer whether to move up building the train box in order to keep on schedule, said Adam Alberti, spokesman for the Transbay Authority. Construction on the new terminal is expected to start in early 2010."
"But even if Transbay officials put the train box on the fast track, there's still debate over whether the current design - one platform and two tracks for Caltrain and two platforms and four tracks for high-speed rail - would be sufficient."