The maximum one-way fare including all possible surcharges is $17.50, the journey between San Francisco International Airport and Oakland International Airport. The farthest possible trip, from Antioch to Berryessa, costs less ($9.95 with Clipper) because of the $4 additional charge added to SFO trips and $6 additional charge added to OAK trips. Entering and exiting the same station within three hours accrues an excursion fare of $5.75. Passengers without sufficient fare to complete their journey must use a cash-only Add Fare machine to pay the remaining balance in order to exit the station.