Even better would be another connection between the two outer tracks, so that a Caltrain departure opposite a parallel Caltrain+CHSR arrival is possible.

From the diary:

The only player that strikes me as having the opportunity to say, "wait a minute, here's a fix that won't cost all that much to implement" is Caltrain. But ... under the solution above, they are giving up a 900 ft. platform, connected to the tail tracks, for what could end up being a 800 ft. platform, with only one connection to the tail track, and that connection only available when the closest HSR platform track is empty.

So, yes, the above, which would make it operationally feasible to squeeze 8tph into four terminal platforms, and which may or may not be physically feasible, does knock on to make things even worse for Caltrain. Efforts to squeeze extra capacity out of the same infrastructure tend to generate bad trade-offs like that.

If there is going to be three tracks, the ideal would be an access track on the one side, an egress track on the other, a bi-directional track in the middle with switches at several points along the tunnel, and an adequate 3:6 fan out including as many dives as necessary to avoid blocking movements.

But the TBT is a property redevelopment project using a transit project as its hook, with the location itself the wrong place for a central rail terminus, and while cut and cover tunneling for the station throat can be useful as an excuse to take over and redevelop certain sites, extra money for an adequate platform access or extra tunneling for dives (and its basically tunneling in mud, so it'll be fairly expensive) ... they are kind of "only if someone else pays for that part".


I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.