quickest" of the options studied, SP stated they did not want to share the existing tracks (and freight service) with increased passenger rail operations, making plans to extend the rails to Second and Market unfeasible. The Third and Townsend Depot was demolished in the late 1970s after the current station at 4th and King opened one block away in 1975. PERSUS and PENTAP In 1975, the Metropolitan Transportation Commission (MTC) published the Feasibility of Upgrading Peninsula Passenger Rail Service (PERSUS) report. PERSUS noted the single largest destination, San Francisco's downtown Financial District, was not directly served by the SP Peninsula Commute and called the Townsend Street station "an obstacle to the [Central Business District]-destined commuter who must expend additional time and fares, and a deterrent to the off-peak rider who must contend with less frequent transit service or pedestrian hazards on the streets." In addition, SFO was "the largest traffic attractor located between San Francisco and San Jose" and "physical conditions for establishing a [rail] link are unusually favorable" because the SP line approaches the airport quite closely. PERSUS proposed three alternatives, which could be implemented in successive phases: Minor Upgrade: retain the existing service and terminals, but improve access to stations on the Peninsula and San Francisco. Major Upgrade: move the San Francisco terminal, increase service frequencies, and begin investment of public funds. Transit Conversion: increase service frequencies so passengers would wait no more than fifteen minutes between trains, separate passenger and freight rail traffic with additional tracks, complete grade separation, and build an airport station. An extension to the Transbay Terminal would be part of the Major Upgrade, with an alternative to terminate SP service at by rerouting the SP line onto the Coast Line through Colma, which had discontinued service after the completion of the Bayshore Cutoff in 1907. The Transit Conversion would free casual riders from having to look up specific timetables and plan trips, obviating the need for a Peninsula BART extension, and it was projected to more than double ridership. PERSUS was followed by the Peninsula Transit Alternatives Project study (PENTAP) in 1977. PENTAP recommended upgraded SP service, including more frequent reverse-peak trains (southbound in the mornings, and northbound in the evenings). As an alternative to extending SP to the Financial District, PENTAP advocated for more frequent bus service to the SP terminal at Fourth and Townsend. The Caltrans CalTrain By the late 1970s,