AirTrain is a fully automated people mover at San Francisco International Airport (SFO) that opened on February 24, 2003. It operates 24 hours a day on two separate lines, covering a total of three miles (4.8 km). The service charges no fares; it is funded by a fee charged to rental car customers. The system is located outside of the sterile area of each terminal, meaning passengers must exit and re-enter through a security checkpoint when using AirTrain to travel between terminals.
