Rapid Transit to the San Francisco International Airport: Alternate BART stub-end alignments to SFIA (1969)
"Alignment C, which stub-ends in the Central Space, may compromise the north-south service on the ultimate regional rapid transit system, if and when there is an extension of that system south. Yet, one should recognize that the technology for the ultimate system may not have the operating constraints of today. Perhaps it will be possible to fit special airport trains into the stream of traffic even in peak periods by the time of a possible extension south. Lacking even this type of improvement in the technology, the line into the airport could be changed to a shuttle."