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Hyperloop

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Re: Hyperloop

#531

Post by dllthomas »

slacka wrote: post #290
tptacek wrote: post #76

Earlier quoted context omitted.

That's an argument in favor of a useful HSR system. But politics have resulted California's HSR system being deliberately pessimized; it may do more harm than good to the HSR cause, right?

“The man who moved a mountain was the one who began carrying away small stones.” -Chinese Proverb I've lived in China for over 3 years, and spend countless hours riding the HSR system. HSR combines the speed of a plane, with the cost and convenience of a regular bus. Traveling through the countryside of China at 380km/h made me feel like I was in the future. Coming home and seeing the the sad state of our infrastruct…

Building worthless HSR lines isn't a necessary or useful step on the road to building useful HSR lines.

Re: Hyperloop

#532

Post by ricardobeat »

lowkey wrote: post #305

Adding a compressor fan to actively transfer air from the front to the rear of the pod while simultaneously serving as an air cushion to support the vehicle is simple, elegant and absolutely brilliant! An ingenious solution appears so obvious in hindsight that it leads you to ask "why didn't I think of that?" While being subtle enough to confound all those who came before. I have been following the developments of th…

I'm pretty sure that idea has been thrown around, maybe even here on previous HN discussions, can't remember. The hard part is having really deep knowledge of the tech involved, manufacturing and costs, and producing a 50-page technical document with input from dozens of top minds in their fields :)

Re: Hyperloop

#534

Post by marshray »

yid wrote: post #102

> Risk of derailment is also not to be taken lightly, as demonstrated by several recent fatal train accidents. Interesting. No comment on the potential outcome of a passenger-filled capsule being ejected from a burst tube on high pylons at 350mph.

If the tube bursts so wide that the capsule could be ejected from it, the inrush of air would likely be so great that capsules probably wouldn't even make it out. The bigger concern would be that they could decelerate too quickly.

Re: Hyperloop

#535

Post by spikels »

dragonwriter wrote: post #484
spikels wrote: post #442

Earlier quoted context omitted.

Not sure why you think there would be more passengers on LA-SF versus SaoPaolo-Rio: Greater populations, shorter distances and lower costs ($17 vs 68 billion). Brazilians may be poorer today but they are catching up fast. Sure there will be private contractors but is there really any private interest in building and/or operating high speed rail in CA? Perhaps Hyperloop will change things but so far it has been govern…

> Not sure why you think there would be more passengers on LA-SF versus SaoPaolo-Rio More potential passengers in the latter, more potential passenger revenue in the former. > Brazilians may be poorer today but they are catching up fast. Per capita GDP in Brazil is less than 1/3 of that in California, and is increasing at about 1.7%/annum (2.7% GDP growth, 0.9% population growth); assuming no growth in California GDP…

People in Sao Paolo and Rio are about 40% richer than average Brazilians which reduces the gap somewhat. And GDP growth in Brazil has averaged 3.1% since 1991 with Sao Paolo growing faster. Costs are expected to be much lower for construction ($17 vs $68B) and probably operation. Also they expect it to take 5 years to build versus 15. Not sure how it would all shake out but does not seem to be a clearly worse project.

It's probably moot comparison anyway as best I can tell the Brazil HSR is not going to happen. There have even been giant protests over transportation and government spending.

I'm also pretty skeptical that CA HSR will actually get built - numbers don't add up and popularity is declining. If they can build and operate the Bakersfield to Fresno segment on schedule and budget it might have a chance - but I have doubts they can even do this.

Re: Hyperloop

#536

Post by gaadd33 »

mjn wrote: post #475
pbreit wrote: post #471

Earlier quoted context omitted.

Uh, the number above is $70b and the TGV was built 30+ years ago so you could at least double that number based on inflation.

Even the most expensive TGV lines, have a per-km cost of around $20m/km in present dollars, and that's high enough to cause controversy. The bulk of the network was built for prices of $2-4m/km at the time, which is about $3-5.5m/km if you adjust for inflation. For a 700-km line like SF-LA, even the $20m outlier cost would work out to only $14 billion. Where's the 8x multiplier coming from? No TGV line has cost >$100…

Maybe the real estate that it goes through is significantly more expensive? I know if you wanted to build a new, totally segregated line from DC to Boston would probably cost 100B easily.

Re: Hyperloop

#537

Post by VladRussian2 »

mjn wrote: post #475
pbreit wrote: post #471

Earlier quoted context omitted.

Uh, the number above is $70b and the TGV was built 30+ years ago so you could at least double that number based on inflation.

Even the most expensive TGV lines, have a per-km cost of around $20m/km in present dollars, and that's high enough to cause controversy. The bulk of the network was built for prices of $2-4m/km at the time, which is about $3-5.5m/km if you adjust for inflation. For a 700-km line like SF-LA, even the $20m outlier cost would work out to only $14 billion. Where's the 8x multiplier coming from? No TGV line has cost >$100…

>I am not sure any line in the world has cost that much, even in inhospitable terrain like China's high-speed rail in Tibet, or Japan's high-speed rail through the mountains.

you should check cost of highways in Moscow - $300M/mile. Hint - it isn't about terrain :)

Re: Hyperloop

#538

Post by nbouscal »

jessriedel wrote: post #267
flyt wrote: post #242

Earlier quoted context omitted.

Weight of the rolling stock.

"For those who don't know the lingo, "rolling stock" just means "all the vehicles on the train." Does he say this explicitly? (Sorry if I missed it.) Why can't you make a train car just as light as these cars, and also skip the weight of the tube?

Train cars must be connected to each other because of how trains work, whereas the Hyperloop pods are separate from each other. I haven't yet seen anyone actually crunch the numbers on the proposed weights for the Hyperloop (which are in the PDF) vs existing light rail solutions. You certainly can put a light rail up on pylons, it just might be a lot easier/cheaper to do so with the Hyperloop. I do think he's playing up the benefits of using pylons too much, since the real benefit here is the 35 minute travel time and affordable ticket cost.

Re: Hyperloop

#539

Post by Anechoic »

Turing_Machine wrote: post #526
krschultz wrote: post #474

Earlier quoted context omitted.

The weight of a 10' diameter steel tube with 1" wall thickness is 125,000 lbf per 100 feet. Note that does not include the reinforcing braces, that is just the plate. The actual weight could be easily 2-4x greater. It also doesn't include the weight of the solar array. My bet is that it's not significantly different to compare a light rail (subway-like) system to a hyperloop in terms of weight.

The weight of the track ballast alone is more than that. Gravel is about 100 pounds per cubic foot, and you need about 12 cubic feet of ballast per foot of track, or 127,500 pounds. Then you get to add the rails and ties (or concrete sleepers), plus the vastly more heavy rolling stock. The reason I said that the weight of the tube doesn't enter into it is because the tube isn't moving. The only thing that matters in…

The weight of the track ballast alone is more than that.

? You don't need to use ballast & tie track on elevated structure, in fact it's rare to do so on modern rail structures.

Re: Hyperloop

#540

Post by yk »

asmithmd1 wrote: post #291

I see just a little bit of hand-waving with how to deal with the 300 psi and 1000 degree F air. He says they will cool it with on-board water and storing the steam (I don't see a pressure here)in the vehicle. Given the tight space, will any kind of thermal insulation breakthrough be needed?

Probably not, the pressure and thus the density of the air is really low and therefore it simply does not have the energy density needed to cause problems.
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