From A History of BART

Between 1957 and 1962, engineering plans were developed for a system that would usher in a new era in rapid transit. Electric trains would run on grade-separated right-of-ways, reaching maximum speeds of 75-80 mph, averaging perhaps 45 mph, including station stops. Advanced transit cars, with sophisticated suspensions, braking and propulsion systems, and luxurious interiors, would be strong competition to "King Car " in the Bay Area. Stations would be pleasant, conveniently located, and striking architectural enhancements to their respective on-line communities.