Hyperloop: Pipes of Fancy • Hacker News Board

Re: Hyperloop: Pipes of Fancy

#271

Post by _ph_ » Thu, Aug 13, 2020, 2:58 PM UTC

Skye wrote: post #245

_ph_ wrote: post #225

Earlier quoted context omitted.

I am disagreeing with the article. Of course, when designing/selling new train systems, a lot of showmanship and gadgetery are involved, but there are real shortcomings with current train systems which cause people to develop new technologies. First of all: trains are great, there are many places where they perform admirably. Many cities have a great subway network, countries like France, Japan, Taiwan and now China…

I have a few nitpicks... Making train tunnels cheaper by making them smaller is not a new idea. it is a very old idea. Have a look at the deep level tube lines of the London underground. In some ways, we regret having trains that small since it reduces capacity and makes it nigh impossible to air condition. It's possible to make normal trains go over existing roads, elevated rail is also a very old thing, a lot of it…

Normal trains are designed to support very high loads, as they are using tracks suitable for cargo transport. For urben people transport, you don't need that carrying capacity, so the rails as well as the trains are unnecessarily heavy. Also, the wagons are larger than needed. It absolutely makes sense to rethink the whole system.

Re: Hyperloop: Pipes of Fancy

#272

Post by sudosysgen » Thu, Aug 13, 2020, 3:03 PM UTC

stevehawk wrote: post #269

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?

What do you do when American citizens shoot at airplanes? Quit flying? Yesterday an Air Force helicopter was shot at and the pilot injured. Not to mention the number of citizens pointing lasers at cockpits. https://www.wusa9.com/article/news/local/virginia/military-h... You can't refuse to do something just because you're scared of a few bad actors. Otherwise we have to stop making cars (they get driven into crowds),…

When an airplane is shot at by a civilian, in 99.999% of cases there will be no big issues (read : multiple deaths).

Making an entire transportation system with hundreds of thousands of people inside that can all be killed instantly by a single bullet or bomb is insane lunacy.

Re: Hyperloop: Pipes of Fancy

#273

Post by sudosysgen » Thu, Aug 13, 2020, 3:06 PM UTC

The_Double wrote: post #214

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?

What do you do when a terrorist places a derailing device [0] on a piece of rail track that will harm and potentially kill many people inside? [0]: https://en.wikipedia.org/wiki/Derail

Derailing a railroad is a complicated endeavor that will likely get detected and the train stopped, and even in the most catastrophic event only a very small fraction of the occupancy of one train will be killed.

Whereas a catastrophic dépressurisation event on a hyperloop will assuredly kill everyone inside. The amount of energy stored in such a pressure differential is equivalent to many hundreds of tons of TNT. It's not comparable at all.

Re: Hyperloop: Pipes of Fancy

#274

Post by 11thEarlOfMar » Thu, Aug 13, 2020, 3:40 PM UTC

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…

"It's about the land."

It seems that the tunneling was meant to solve this in urban areas. Open farmland is easier to manage, perhaps leasing the strip from the owners, gaining right-of-way over roadways by working with local governments.

Re: Hyperloop: Pipes of Fancy

#275

Post by sudosysgen » Thu, Aug 13, 2020, 3:46 PM UTC

specialist wrote: post #259

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…

"High speed rail on a large scale is really something that has to come from the government." We learned about this in highschool history. From wikipedia: The Pacific Railroad Acts of 1862 were a series of acts of Congress that promoted the construction of a "transcontinental railroad" (the Pacific Railroad) in the United States through authorizing the issuance of government bonds and the grants of land to railroad co…

You can also, like the French or the Canadians or the Germans or really most countries, have your public transport infrastructure be outright publicly owned. Presuming the government is competent, of course.

Re: Hyperloop: Pipes of Fancy

#276

Post by sudosysgen » Thu, Aug 13, 2020, 3:56 PM UTC

Robotbeat wrote: post #151

jojobas wrote: post #98

Earlier quoted context omitted.

Three words: vacuum expansion seals.

There are multiple ways to solve this problem. It’s not a showstopper. 1) Bury the lines. Basically isothermal at depth. 2) insulate the tube and maintain stable temperature 3) use materials that don’t drastically change length with temperature 3) allow the tubes to change length. Put them on rollers. 4) use vacuum expansion joints just like us common in vacuum engineering. People act like vacuum is this new thing. P…

No one has ever made a vacuum tube 600km long with a cross-section of over a meter. Much less one that has to maintain vacuum with a super heavy train going at 400m/s. This is at least an order of magnitude more difficult than anything of the same nature. It's really not comparable to anything in existence. CERN is a Tonka truck by comparison.

Burying the lines would already make it an order of magnitude more expensive than what was promised. And now you have to compensate for ground movements, since your tube is fat and hundreds of kilometers in length, which makes it even more expensive.

Insulating the tubes to maintain temperature would be incredibly costly, and if there ever was a failure or natural disaster that prevented you from keeping up the power need, your tube will break.

Materials that have such little temperature change coefficients are much too expensive to build a 600km long multiple meter wide tube with.

If you allow the tubes to change length, your stations will move, sometimes in unpredictable directions. You also risk gigantic stresses caused by temperature differentials causing bending forces.

Vacuum expansion joints of that scale, for such a length, with such reliability are literally unheard of. And would likely be insanely expensive.

Re: Hyperloop: Pipes of Fancy

#277

Post by sudosysgen » Thu, Aug 13, 2020, 4:03 PM UTC

Robotbeat wrote: post #155

aaron695 wrote: post #131

Earlier quoted context omitted.

The entire point of the Hyperloop is to get around right of way and politics. That is it's design. That is exactly what Elon is doing. You might argue it can't do what it's setting out to achieve, but this has never been a technological solution. He's designed a technology to fit with current societal processes rather than the old, get society to accept a technology.

Exactly this. That’s why The Boring Company is focusing on reducing the costs of tunneling dramatically. And they started by just using existing technology. With that (and without the cost inflation that many corrupted projects experience), they were able to achieve about $10 per mile of tunnel. A lane of highway per direction is $1m to $8m depending on if it’s rural or urban. They’ve developed a new machine, Prufroc…

So, just the tunnel, with nothing else, at small diameters, is $10m per mile. Whereas it's possible to build high speed rail, including the stations, fully furnished, for 15-20 million dollars per mile. Does not compare favourably, at all.

Re: Hyperloop: Pipes of Fancy

#278

Post by therealdrag0 » Thu, Aug 13, 2020, 4:07 PM UTC

heavenlyblue wrote: post #195

therealdrag0 wrote: post #72

Earlier quoted context omitted.

I think the implication is that pessimists don’t try.

Your assumption is only true if trying never has a negative downside.

I don’t see how that follows.

Re: Hyperloop: Pipes of Fancy

#279

Post by sudosysgen » Thu, Aug 13, 2020, 4:15 PM UTC

kanox wrote: post #188

liability wrote: post #107

Earlier quoted context omitted.

> "Can someone explain me how Hyperloop is supposed to work?" 1) Mass transit competes with cars. 2) Elon Musk sells cars. 3) High speed rail projects get derailed by people saying "but if we wait N years we could build a hyperloop instead" That's how Elon Musk intends Hyperloop to work.

This is one of the sillier Elon conspiracy theories. Tesla competes with gas cars, not trains.

Once Tesla is done competing with gas cars, it will also compete with trains and airplanes. Remember GM trying to scrap public transport projects?

Re: Hyperloop: Pipes of Fancy

#280

Post by jcranmer » Thu, Aug 13, 2020, 4:30 PM UTC

sudosysgen wrote: post #279

kanox wrote: post #188

Earlier quoted context omitted.

This is one of the sillier Elon conspiracy theories. Tesla competes with gas cars, not trains.

Once Tesla is done competing with gas cars, it will also compete with trains and airplanes. Remember GM trying to scrap public transport projects?

> Remember GM trying to scrap public transport projects?

I'm assuming you're referring to the GM streetcar conspiracy here. What GM actually did was try to monopolize the supply of buses--which is still a form public transport. They also did buy out several streetcar lines, but the streetcar systems they bought were already bankrupt or on the verge of bankruptcy. There's no real difference in the trajectory of streetcars in the cities which were bought out by GM and those in the cities were they were not bought out.