Unfortunately my comment about BART was only half in jest.

I doubt that the engineers at HSR are at all excited about building any one of the three levels of European railway you describe. BART broad guage was not a fluke - the bosses did not want interchange or interoperability. You start to see the same pattern of blunders with the HSR and you have to wonder who's puppeteering this time.

I'll probably get into trouble for this comment but perhaps it best illustrates my way of thinking. Europeans will never fully understand Americans because in Europe intelligence is revered whereas in the US we just love our professional, in your face and proud of it stupidity. When I was a kid in the fifties my friends and I used to memorize the comic routines of Lenny Bruce, who was our guru in those dim McCarthyite days. He used to do an imitation of Oral Roberts which ended with something like:

"Yes I am dumb. I don't know how much a whole lot of 9's are. Yeah I'm dumb, I got three Lincoln Continentals - that's how goddam dumb I am!"