For urban railways, stations are usually the capacity-limiting factor, so the top speed doesn't really enter into it, and besides > though I'm not sure it hits

For urban railways, stations are usually the capacity-limiting factor, so the top speed doesn't really enter into it, and besides > though I'm not sure it hits those speeds within San Francisco. due to the shorter station spacing I'd assume that, too. As for the stations, the limiting factor in turn consists of the sum of dwell time (wheel stop to wheel start) and platform reoccupation time (governed by the signalling system).