Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Hyperloop: Pipes of Fancy

economist.com

Post reply on HN
Print view View original

141–150 of 322 posts

Re: Hyperloop: Pipes of Fancy

#141

Post by jeffreyrogers »

TylerE wrote: post #10
jeffreyrogers wrote: post #5

Hyperloop has sex appeal, but it seems like Maglev or just plain old high speed rail makes more sense from an economics perspective. I can't imagine it's cheap to keep a tube evacuated. Either way, it seems good to try and build these sort of high-tech industries in the US.

It doesn't have to be that good a vacuum. It's probably really no more expensive than conventional high speed rail. The hyperloop proposal is operating at approximately 1 millibar of pressure. That sounds CLOSE to a vacuum..and it is, roughly 0.01 atm, but with vacuums getting down to around there is easy. Getting down to, say, 0.00001 atm is much much much harder.

But you aren't just doing it a chemistry lab. You're doing it in an enormous tube and the tube has openings to allow pods in and out, so it's a lot more complicated.

Re: Hyperloop: Pipes of Fancy

#142

Post by jeffreyrogers »

sudosysgen wrote: post #110
captainbland wrote: post #85

Earlier quoted context omitted.

It may not be totally evacuated but the pressure difference between it and the outside world is still supposed to be very large isn't it? And if you want a hyperloop that actually goes anywhere that's going to represent quite a large volume of low pressure space that you need to create and maintain. Surely this has to be quite energy intensive and generally difficult to maintain, especially since you have to get peop…

Another thing, is that anyone that punches a hole big enough in the tube basically transforms half of the hyperloop into a bomb. Energy = pressure * volume. That's a lot of energy smashing through a hyperloop capsule. Basically, imagine if 3% of the tube was filled with pipe bombs, but in reverse.

Also, what happens if the pods leak? Seems like the air in the pods will diffuse through the tube and the people will suffocate.

Re: Hyperloop: Pipes of Fancy

#143

Post by ClumsyPilot »

yellow_postit wrote: post #120
sudosysgen wrote: post #109

Earlier quoted context omitted.

What do you do when a terrorist shoots a hyperloop tube causing a pressure wave that will kill everyone inside?

You avoid building it (above ground at least) in the first place

A digging / drilling accident, an earthquake or sinkhole. If we are still talking about terrorists, they grab a shovel?

Re: Hyperloop: Pipes of Fancy

#144

Post by owenversteeg »

owenversteeg wrote: post #47
AlexandrB wrote: post #9

This is evergreen when talking about Hyperloop: http://www.cat-bus.com/2017/12/gadgetbahn/ The problems with building this have nothing to do with technology but with right-of-way, investment, and politics. If those factors were solved, we'd already have high-speed rail in places where Hyperloop has been proposed. The fact that we don't says that Hyperloop is unlikely to be feasible as well.

That "Gadgetbahn" article is great, but I do have one criticism. From the article: "If the idea is viable and the people behind it are competent, it should have attracted private investment, as there should be a potential to make profit selling the technology. After all, the proposal has been around for 23 years." High speed rail on a large scale is really something that has to come from the government. While there a…

Since this is getting to be a bit popular, I'm going to push the "technology really doesn't matter" point a bit more here: in 1955 the French built this [0] (just look at the picture!) and sent it down a traditional (wooden sleepers, rocks for ballast) rail line between Bordeaux and Irun [1]. It got up to 333 km/h, which is faster than any TGV currently operates in the year 2020 on their fancy concrete HSR tracks.

[0] https://en.wikipedia.org/wiki/File:SNCF_BB_9004_photo_1.JPG

[1] Side note: that bit from Bordeaux to Irun is quite possibly my favorite train line in the world. Absolutely beautiful views towards the Irun end.

Re: Hyperloop: Pipes of Fancy

#145

Post by ClumsyPilot »

TylerE wrote: post #10
jeffreyrogers wrote: post #5

Hyperloop has sex appeal, but it seems like Maglev or just plain old high speed rail makes more sense from an economics perspective. I can't imagine it's cheap to keep a tube evacuated. Either way, it seems good to try and build these sort of high-tech industries in the US.

It doesn't have to be that good a vacuum. It's probably really no more expensive than conventional high speed rail. The hyperloop proposal is operating at approximately 1 millibar of pressure. That sounds CLOSE to a vacuum..and it is, roughly 0.01 atm, but with vacuums getting down to around there is easy. Getting down to, say, 0.00001 atm is much much much harder.

From a safety perspective 0.01 atm = 0 atm. That tube is either very dangerous, or very overbuilt and expensive.

Re: Hyperloop: Pipes of Fancy

#146

Post by pilaf »

anitil wrote: post #97
GuB-42 wrote: post #45

Can someone explain me how Hyperloop is supposed to work? There are so many things wrong with it. - Hyperloop is a vactrain, a century old idea, and to this day, despite numerous attempts, nothing came close to a working prototype, let alone something production-ready. - By contrast, high-speed trains carries millions of passengers every day in many parts of the world. They are safe, comfortable, and commercially via…

It's very irritating talking about whatever hyperloop is, because that the bar for what the hyperloop is keeps changing (Is it tunnels? Is it in a vacuum? If there's no vacuum isn't it just a tunnel? Is it your own car or a pod? There's solar panels somehow?). If we wanted better transport we should invest in busses and trains, which have better carrying capacity and better failure modes than whatever hyperloop is su…

> It's very irritating talking about whatever hyperloop is, because that the bar for what the hyperloop is keeps changing (Is it tunnels? Is it in a vacuum? If there's no vacuum isn't it just a tunnel? Is it your own car or a pod? There's solar panels somehow?).

The Hyperloop concept is exclusively a pod in a vacuum tube. The electric cars in a tunnel concept is called the Loop (no Hyper), and it's a different idea entirely developed by Musk's Boring Company (which in turn has no involvement with Hyperloop development). The names are very similar, which has caused a lot of confusion, even in mainstream media reports.

I mostly agree with the rest of your comment.

Re: Hyperloop: Pipes of Fancy

#147

Post by sudosysgen »

pilaf wrote: post #139
sudosysgen wrote: post #108

https://www.youtube.com/watch?v=4dn6ZVpJLxs This video has most of the points about why the Hyperloop is a ridiculous idea that will never work.

That video doesn't talk about the Hyperloop at all. You're getting the Boring Company's Loop mixed up with the Hyperloop, which despite the similar-sounding names have close to no relation.

Ah yes, I posted the wrong video. My bad.

Re: Hyperloop: Pipes of Fancy

#148

Post by ClumsyPilot »

cs702 wrote: post #4

"A hyperloop system involves passengers or freight transported by pods elevated by magnets, which travel within raised pipes. The pods can be propelled at 620mph (1,000kph), says Jay Walder, boss of Virgin Hyperloop One, one of the firms pushing the idea. At that pace 'you could move between Columbus and Chicago in 40 minutes', he says, so covering the 460 miles many hours quicker than by driving and at a cost (and o…

Lower than flying. Train are the most efficient, simplest and oldest form of land transport. Where do you get the idea that hyperloop can even approach efficiency of a car, with all the energy wasted on high speed and keeping up near vacuum?

Re: Hyperloop: Pipes of Fancy

#149

Post by roywiggins »

titzer wrote: post #132
owenversteeg wrote: post #47

Earlier quoted context omitted.

That "Gadgetbahn" article is great, but I do have one criticism. From the article: "If the idea is viable and the people behind it are competent, it should have attracted private investment, as there should be a potential to make profit selling the technology. After all, the proposal has been around for 23 years." High speed rail on a large scale is really something that has to come from the government. While there a…

> The uncomfortable part of HSR, of course, is that no matter how perfect your government is, it's going to involve bulldozing some people's homes, conflicting with other government projects, and interfering with nature. Don't get me wrong, I'm not part of team "screw the law, bulldoze straight lines between cities, people and nature be damned". But there do need to be sacrifices made. And a strong, coordinated gover…

During the era of freeway construction they usually built the enormous interchanges through marginalized neighborhoods. Nobody with political power cares because they don't live there; nobody who lives there can prevent it happening.

Re: Hyperloop: Pipes of Fancy

#150

Post by akiselev »

titzer wrote: post #132
owenversteeg wrote: post #47

Earlier quoted context omitted.

That "Gadgetbahn" article is great, but I do have one criticism. From the article: "If the idea is viable and the people behind it are competent, it should have attracted private investment, as there should be a potential to make profit selling the technology. After all, the proposal has been around for 23 years." High speed rail on a large scale is really something that has to come from the government. While there a…

> The uncomfortable part of HSR, of course, is that no matter how perfect your government is, it's going to involve bulldozing some people's homes, conflicting with other government projects, and interfering with nature. Don't get me wrong, I'm not part of team "screw the law, bulldoze straight lines between cities, people and nature be damned". But there do need to be sacrifices made. And a strong, coordinated gover…

Interstate highway construction slowed dramatically in the 70s after federal funds largely dried up except for the remaining critical arteries like the Colorado I70. Since then, a dozen highways proposals have come and gone because of eminent domain and environmental impact lawsuits in Southern California alone.

The I710 expansion, for example, was finally axed a few years ago after six decades of opposition from South Pasadena and the surrounding cities. At one point the state was considering a plan to tunnel under the town for about a $billion a mile because the opposition was so intractable (well funded and connected) before Caltrans gave up and started selling all the housing they'd been accumulating for decades for the project.

Post reply on HN