I guess. I'm not sure it makes that much difference.
Here's my original example:
> BOS->WAS (413 air miles) is certainly the best example we have in the
> US, especially since there's no non-stop service into National from
> Boston: you have to get into Dulles instead. Interestingly, the
> Acela Express on this route takes a little over 6:30 one way.
Tokyo -> Hiroshima is 425 air miles and takes 4:39 and is on a straight route (as opposed to BOS->WAS having to detour into NYC). It's still way longer than flying (about 1:20, plus transfers).
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People who want faster trains in the US mostly just want the cities to be closer together. SEA->MIA is about 2700 miles; the longest leg of Shinkansen is less than 500 miles, and it takes all day; certianly too long to go r/t in the same day and still get some work done in the middle, which is my benchmark for "short, fast" trips.
Oakland -> San Diego is 446 air miles. I used to regularly drive to the airport from Berkeley, hop Southwest, rent a car, drive to La Jolla, work a good 7-8 hour day, and fly back, about 4:30 total travel time.
Sure, that's a long day; but it's just about impossible on Shinkansen.
/jordan