One thing that nobody has mentioned - autonomous cars. Close to the time this will be completed, I assume I'll be able to sit in my vehicle and be shuttled from SF to LA in 5 hrs in the comfort of my own vehicle.
I suppose if you regard sitting in a seat not being able to move as comfortable.
But before you get too relaxed in that glorious possible future:
1) high speed trains exist and proven - no new science or engineering to figure out
2) autonomous cars are constrained by the realities of space to put the vehicles. Too many vehicles, autonomous or otherwise = congestion and slow travel.
3) At 6 hours, this is nearly twice as long as the train will be.
4) In the autonomous car, you will need to stop for food and bathroom break. The train does not need to stop. So your trip time is extended, especially true with kids.
5) At 3.5 hours, someone can leave for LA at 6am - get to a 10am meeting and return in time for dinner and bed. Not going to happen if each direction takes 5-6 hours.
I really like high speed trains but have you paid for them? They are great for business where you need to go somewhere and come back, but for a family of 4 they are extremely expensive. From Tokyo to Osaka ~350 miles, it's about $130 per person each way on the Shinkansen. For 4 of us (2 adults, a child, and a free toddler), it would be ~$650 for round trip tickets.
The problem is that same person can pay about $50 for gas to go from SF to LA and have the car with them in LA or pay $130 for a one way ticket (I haven't read the numbers but that's about the cost in Japan and I expect other countries with high speed rail). Then you have to get to the station which might be a little far for some.
I really love the high speed rail system in Japan and Europe but it's not cheap.
Normally I'm as skeptical of autonomous vehicle timeframes as anyone. But this is a case where even just the highway portion would be a huge win. And one of the cities (as well as pretty much all the intermediate locations) aren't very public transit or pedestrian friendly.
If I'm leaving SF and will be in LA in 5-6 hours (door-to-door) with a minimum of driving [ADDED: with my own vehicle], how attractive is that train?
I do get the efficiency of train travel but if you're already skeptical that the numbers work...
Once autonomous driving works well, I see no reason why cars can't scream along I-5 at twice the current speed, too. So five hours could become three and a bit, door to door.
They could even autonomously draft behind each other for maximum efficiency. Cars could be designed with high speed drafting aerodynamics in mind. With that, a line of cars might actually be more energy efficient than a high speed train running at typical occupancy levels, or at least competitive.
I'd be surprised if a "car train" running on rubber tires, even if as aerodynamically efficient somehow as a high-speed train, could ever match the same efficiency per occupant-mile. Ignoring everything else, steel wheels on steel rails have a massive efficiency advantage from lower rolling resistance alone - and a train carrying 400 people is going to have far fewer wheels per passenger than a "car train" carrying 400 people.
Yep, rolling resistance is the big factor in favour of the train.
The big factors for the car-train are much smaller cross sectional area and the fact that it's always exactly as long as it needs to be, unlike the train which needs to run even when it's mostly empty.
Once you have steel wheels, air resistance is the main problem. For trains it largely only depends on the nose of the train, then the length doesn't really matter. Since your "car train" isn't smooth, it'll have much more overall air resistance.
The car is slower, and an order of magnitude less efficient. And efficiency matters -- there's a limit to how much energy can be sustainably spent, and if transportation is more efficient, we get to do more other things.
Not to mention that the US is going to continue to expand in terms of population. We've added 60 million people in 20 years, nearly equal to the population of France. We'll add another 20+ million in the next decade.
Simultaneously we'll become slightly less rural and more urban in terms of population concentration.
Even if the autonomous electric vehicle has a huge role to play in improving traffic in the US - which it clearly does - high speed rail (whether hyperloop-like, above ground, below ground, whatever) will still make sense alongside that. There is going to be plenty of demand to go around, such that having multiple approaches will be useful. Sometimes the autonomous car will make sense, sometimes rail will make sense.
Only in theory - current estimates are that by the time stops, noise abatement, track changes, etc have all been factored in, the CAHSR trains will average under 100MPh - closer to 80, which is easily achievable on i5 by a car.
