Ok, so how is this cheaper than high-speed rail in a tunnel?

It seems to me that hyperloop is high speed rail with the addition of a vacuum, which gets you higher speed. The additional requirement of a giant vacuum tube should make the system cost more, not less.

Personally, I’m rooting for Elon Musk to figure out how to make tunnels cheaply with the Boring Company, so we can take that tech and use it to build a bunch of subways. Traffic within urban areas and suburbs is a much bigger societal issue than intercity travel anyway. Subways are a proven solution, but somehow we lost the ability to dig tunnels economically so we stopped building them.

Tunnel boring is actually not that expensive, for some projects the raw tunnelling isn’t a big portion of the overall cost. I think for crossrail in London (which includes a fair amount of tunneling ), the tunneling is 10-20% of the total Prüfer cost.

A large amount of cost is in the stations.

In the us, a large amount of cost is inefficiency, projects cost much more than elsewhere, even considering purchasing power parities. Alon levy has written and talked about it extensively, e.g. https://pedestrianobservations.com/2019/03/03/why-american-c...

It uses a much smaller tunnel.

Which means the throughput per tunnel is more expensive, right? A tunnel with a half diameter will have a quarter the throughput (i.e. the ratio of circle diameter to area). Which is why TBM tech develops towards bigger machines, not smaller ones.

Why does a hyperloop fit in a smaller tunnel than a train? Doesn’t it need to do everything a train does, plus it’s wrapped in a vacuum tube?

As far as I understand, the original proposal relies on a) no safety egress walkways in the tunnel and b) a more cramped vehicle profile.

I don't know how as-actually-built hyperloop compares to rail tunnels.

But that's offset by it managing much lower peak passenger throughput, so you need more tunnels...

You don't need more tunnels -- you just limit your passengers to your most profitable, and make a luxury transit system rather than a mass transit system.

This is what Tesla did by starting with the Tesla Roadster then Model S then Model 3... and it's what the Hyperloop aims to do. Launch as a small throughput luxury product and if it's profitable then it doesn't matter if it ever expands beyond that or not.

Two of the largest sources of air pollution in the world are cars and airplanes, and Elon Musk has already been working on attacking the issue of car pollution. Imo extrapolating out from the combination of SpaceX and Starlink, subways are an obvious project for the Boring Company, especially once you have higher-speed boring machines. (Current boring machines move at about 10 meters/day.)

I don't get it. Subways run off electrical power since the late 19th century. If your grid power is carbon neutral, so are those subway trains.

If that were true, conventional rail would be built mostly in tunnels.

It is very much not.

Tunnels are used only when absolutely necessary to deal with terrain.