San Francisco International Airport is one of the busiest
passenger facilities in the country, and
its transportation access has been massively upgraded in recent years.
A people-mover, known as AirTrain, serves all the terminals and also
provides access to the
car rental area, located some distance away.
the top level visible in this photo, and BART occupies the next level down.
A joint station, with its curved roof partially visible behind where one branch of AirTrain
veers off to the right, allows BART passengers to continue on to their specific
airport destinations on the circulator.