JMann brought up a good point: what about the station tracks and maintenance yard? Granted, Caltrain does their major maintenance down south somewhere (Cahill St.?), but they need a parking place in SF to stage peak time trains. That will be especially true once they move (someday) to the Transbay because there won't be nearly a dozen tracks available in the station to park trains on all day - more like 6 or so if I remember earlier discussions correctly - so trains will need to be staged nearby and moved in/out of the terminal as needed. But Ed wants Caltrain gone from SoMa (and it is potentially valuable land); so where else? I don't think staging in, say, SSF or Bayshore would work well for managing a stub-end terminal 4-5 miles away when you're trying to dispatch trains from the terminal every few minutes in the PM or absorb that many inbounds in the AM.

Caltrain, as the story notes, has been working on a connection that essentially peels off the existing tracks and goes underground from near the 4th St. station to the Transbay. Ed's scheme throws a box of wrenches at that idea, which has already had a lot of money spent on it (preliminary environmental, concept engineering, planning for electrification, even some HSR diddles). Ah well, so it goes in The City these days. Remember when it was The City That Knows How?