The SFO AirTrain will shut down between 9:15 pm on Thursday, Oct. 18, and 6:00 am on Friday, Oct. 19 for power rail replacement. Another closure will occur during the same hours on Thursday, Nov. 1 into Friday, Nov 2. BART will continue regularly scheduled service during these times.
Frequent bus service will replace AirTrain between the terminals and to/from the Rental Car Center. Download the map (.pdf) for details. Passengers arriving on BART can either walk to the domestic terminals (the best option for Terminal 3 especially), or go outside the BART station to the front of the International Terminal, Center Island, where airport staff will direct them to the correct blue SFO Shuttle bus. Note that all buses leaving the International Terminal operate first to the Rental Car Center or long-term parking, so BART passengers should allow at least 20 minutes to get to their terminal, or alternately may wish to walk. Airport staff will be on hand at the bus stop to direct passengers.
Returning to BART from the terminals, the bus trip is direct and omits the Rental Car Center or long-term parking.
For more information about the SFO AirTrain or San Francisco International Airport visit http://www.flysfo.com/.
Updated October 16, 2012: Added link to SFO announcement, updated map