Ah, thanks for the reminder there are passing tracks already.
Are passing tracks really practical? Wouldn't they have to be extremely long to accomodate high speed trains mixed with local Caltrains? I have a hard time picturing this all working out even under ideal circumstances.
Usually they pass when the local train is at the station. This doesn't take all that much space; speed delta is 80mph (125mph once they grade-separate everything). Everything is computer controlled.
It occurs to me that this might be why they've chosen those particular areas. Sunnyvale, Redwood City, Hillsdale, Millbrae, and South San Francisco (just south of Brisbane) are all baby bullet stops, where all of the local, limited, and express trains stop, and so you can reliably count on every Caltrain stopping there and letting a HSR train pass. Cal Ave is the odd one out, but it still has local + limited service.
Are passing tracks really practical? Wouldn't they have to be extremely long to accomodate high speed trains mixed with local Caltrains? I have a hard time picturing this all working out even under ideal circumstances.