[hugh4]

> It will still win energy-wise.

What are we basing that on? Let's look at some numbers:

https://en.wikipedia.org/wiki/TGV

Let's take the Eurostar trains as an example:

> The Three Capitals sets are 394 m (1,293 ft) long and have 766 seats, weighing 752 tonnes.

Most of the other trains seem similar. The mass is about one tonne per passenger. So in terms of mass of metal you need to drag around per passenger, a full train is very similar to a small car (say, the latest model Mazda Miata which weighs 1056 kg) occupied by a single passenger.

But of course trains are very rarely entirely full (and cars average more than one passenger). But the whole mass of the train needs to make the journey regardless of whether there's people onboard or not! The train I caught the other day was probably dragging around ten tons of metal for every passenger. This is what makes trains a horrendously energy-inefficient means of transport.

Aerodynamics? Self-driving cars could draft behind each other at high speed. Probably not a drag coefficient quite as low as the aerodynamically designed train, but it also has a colossally lower cross sectional area, because a train is ridiculously high and ridiculously wide (in the interests of not being ridiculously long, and also for historical reasons).

What else? Oh yes, the car doesn't have to stop 'til it reaches the destination, trains tend to have stops along the route.

For speed, I don't see any reason why, once self-driving is solved, you couldn't have cars cruising at 200mph+ in self-organised "trains" on the existing I-5. No present car is really optimised for that kind of thing, so it's difficult to say how hard it would be, you'd need different tyre compounds for a start.

As for comfort I'll take the privacy of my own little bubble over travelling in the close company of four hundred random strangers.

[guard-of-terra]

It won't be your own little bubble. You're not going to own a 200MPH autonomous car. You will lease it by hour.

And even that is very far away. Meanwhile trains just work. No high-speed connection between LA and SF is an anomaly by world standards given size, proximity and economical importance of two cities.

Also, modern high-speed trains don't have 4-person compartments (or have those at premium), they are rows of seats not unlike plane business class seats. You usually have power, sometimes wi-fi. You can get coffee and a newspaper.

[lorenzhs]

ICEs in Germany have 6-person compartments at no extra charge. You can choose where you would like to sit when making a reservation (compartment or open space (table or no?), window or aisle seat?), or hope that there will be empty compartments.

[CamperBob2]

You're not going to own a 200MPH autonomous car. You will lease it by hour.

I don't want to own it. I don't have to own it. The transit authority can own and operate it.

This will be so much better than fixed-track transit it's not even funny.

[guard-of-terra]

Why? I can understand that for short trips but not for 3+ hours.

[CamperBob2]

Let's try an experiment. Let's meet in the lobby of an office building in the middle of downtown LA, and see how long it takes each of us to get to a bar in downtown SF. Loser buys the drinks.

You fly at 500 MPH, I'll drive at 65-70 or whatever the speed limit on I-5 is these days.

I will win this bet, most likely. You will lose. A train won't help you much, if at all, because it's going to embark and disembark on its own fixed schedule, probably in some crappy/scary part of town miles away from where you need to go. (Here's another reason: eventually some terrorists are going to attack the train. The TSA will muscle its way in, and you'll have to arrive at the station an hour or two early, just like we do now when we fly.)

There's just too much hassle and overhead involved in multi-modal transit... which is why people who can afford to drive still do, even when they have alternatives.

[ctolsen]

Perhaps you'd like to get some actual numbers behind your claims?

And not stuff like "trains are very rarely entire full". Of course they're not. But cars are almost always entirely empty.

[hugh4]

Hey, I'm trying to throw some actual numbers into the discussion in response to the assertion that trains are more efficient. Perhaps those who want to make that claim can start supporting their own? Give me something to work with here.

Rolling resistance is the big issue that usually favours trains. On the other hand, could we design cars with an extra set of wheels or something?

[cardinalfang]

Two vehicles capable of 300kph: TGV: 500 seats 8800kW BMW M5 5 seats 440kW

For long distance/high speed aerodynamics is more important than weight.

[CamperBob2]

Then let's buy 68 million airplane tickets for everyone who will ride this train. The cost will be the same.