> What takes 10 hours in a flight will take 13 hours on fast trains.

How do you figure that? I'm thinking out loud here: If we use some real examples: I'm lucky in that most of my family lives near major travel hubs, so I can fly direct most of the time. However, they all live in various places along the east coast of the US whereas I'm on the west coast. My trip last summer to see one group of them represented a 3100 mile / 5000 kilometer journey.

The flight was 5 hours and 30 minutes. Let's add 2 hours of airport shenanigans to cover showing up ahead of boarding, handling bags, picking up luggage on the far side, etc. So 7 hours 30 minutes of travel (not counting commute to or from airport, but you'd have to get to your high speed rail station as well)

(as an addendum, I was able to take public transit on both sides - busses & BART on the bay area side, and a local commuter rail on the far side. I had to get picked up by car from the train station though, no busses in that town)

The fastest Japanese and European high speed trains go 300 km/hr. That's 16 and a half hours of rolling at top speed - no stops, slowdowns, sharing slower track, etc. If you stop at major cities along the way (say one stop per US state), you're probably looking at 20 hours of time on the train - each stop meaning you have to stop for 5-10 minutes, slow down and speed up, generally not be able to hit top speed in the confines of the city, etc.

The transit time would be nearly triple in the best case scenario for a coast to coast flight in the US.

The only thing I can think that would mitigate this is, as you said, sleeper cars. West coast to east coast is generally considered a lost day between the travel time and the timezone shift. I guess if you start your train journey in the early morning and sleep on the train that evening, arriving in the early morning next day, it could make up for the "get to the family's place and immediately go to sleep" pattern. You're just sleeping enroute rather than at your destination.

For "mid range" journeys, take a bullet train trip I did in Japan: Sendai -> Hiroshima. I spent 6 hours on the train, the flight would've been about and hour and a half plus the extra 2 hours of airport fun. Because it was a vacation I wasn't going to meaningfully fill the "saved" 2 to 3 hours and the train was way more comfortable. But, for business travel, this wouldn't have been good. In the US it's not an uncommon pattern to take a flight to the next major city for same-day business to avoid hotel costs.

For flights so short the airport time exceeds or matches the train difference, obviously this doesn't matter (e.g. SF <-> LA travel if California high speed rail manages to survive until completion).

But you may be sent from SF to Chicago and be expected to attend meetings upon arrival. Can't do that with high speed rail. Even if they went 50% faster, it'll take 7-8 hours to reach Chicago from California.

For the record, I love high speed trains. I've enjoyed using them in the countries that have them. But the longest journey I've ever taken on one is that Sendai to Hiroshima trip, and the second longest is Munich to Berlin (I originated in Innsbruck, Austria but the leg to Munich was not on a high speed train).

It'd be great if we could replace "intra-state" or "neighboring-state" flights with trains, places where they really are faster or at comparable travel times. Obviously none of this is looking at the fact that all of these high speed trains are electric, so they could be powered from zero-carbon or carbon-neutral sources, whereas air travel is a significant source of emissions. But that's a separate argument.