Complex sentence: As someone not from the Bay-area, BART is really the only use of the acronym I think of, cursory skim of the DAB page brings up no others that would be any more primary a topic than the rapid transit system.
Split into simpler sentences: As someone not from the Bay-area, Bay Area Rapid Transit is really the only use of the acronym I think of when I hear it. A cursory skim of the DAB page brings up no others that would be any more primary a topic than the rapid transit system.