The dispatcher requests that all eastbound trains be held at Oakland. From Oakland to San Francisco is Westbound. On BART, if Eastbound trains need to be held, they are held in San Francisco, prior to entering the Transbay Tube. The Tube runs under San Francisco Bay and is more vulnerable to earthquakes than either the subterranean tunnels under SF or the elevated structures in Oakland.
When Evan and Dustin are riding her motorcycle over the Bay Bridge Eastbound (from San Francisco to Richmond), they drive over the top deck of the bridge. This deck is for Westbound traffic.