The Hyperloop was never meant to be built. Elon Musk admitted it was all about fueling opposition to California’s high-speed rail project so it would get canceled. He never planned to improve transportation;
The vision seems like an exclusive tunnel for Tesla owners rather than a viable form of transport. Actually, I’m not really sure what it is anymore, since there appeared to be a weird one that was basically a Tesla tunnel, and another that had maglev capsules or something. Not sure either seems like the best idea ever, but I doubt decent trains will ever exist in the US, so perhaps it’s better than nothing.
Is there any reason to go with low-pressure tunnels at all? For example, having a plexiglass tunnel at .5 atm doesn’t sound that dangerous to me, and it should be easier to build and maintain, but does it actually provide any irl benefit? Like what’s the production costs/train speed/energy savings relation here? What’s the highest low pressure that starts to make sense? Like, do you have to go down to .01 atm, or can .1 or .5 provide enough of a benefit? If not now, what kind of material advances might help?
Just curious about long-term feasibility of that whole thing.
Having a consistent pressure (fully tunnel or fully open air) might help, as the shinkansen needs the very long-nosed trains to help with the ‘pop’ entering or leaving a tunnel.
However that could also be alleviated with the concrete tubes at the end of each tunnel that gradually get more enclosed
@perviouslyiner@fearout The ORIGINAL concept was a low pressure tube with a train in. If this could be done it could reach aviation speeds. I make no comment on how low the pressure would need to be for say 700mph, but this is hard.
However, as a comment early on in the link explains, nobody has built one because it's hard. Billionnaires who get interested in this end up building very short train lines. Elon Musk's Hyperloop is a system of trucks that carry cars, which is just a ridiculous idea.
@perviouslyiner@fearout IMHO there is no good reason for people to travel at more than 300mph or so. There are no sustainable ways to do so with current technology, and the fastest way to cut aviation emissions is to stop flying. Flying is much too cheap given the harm it causes, and public transport is too expensive given how efficient ecologically it is.
That does mean much less travel between America and Europe. But so what? You can holiday closer to home. If your relatives moved several thousand miles away, they probably don't want to see you anyway. 😀
Hi, aerospace engineer here. As far as benefits go it depends.
If we assume the tube is constant volume and constant temperature. The ideal gas law says that in this case, the pressure would change proportionally with density. So if you lower the pressure by 50% the density should lower by about 50%.
Drag force is also proportional to density. So a 50% decrease in density will result in a 50% decrease in drag. This is true for subsonic speeds. The speed of sound is 343 m/s or 770 mph.
Drag also has a square relationship with velocity. So drag gets extremely high when there is an increase in velocity.
If we take the speed of the shinkansen(90 m/s or 200mph) as a baseline and lower the pressure by half. The new speed the Hyperloop would be able to travel with the new speed is 127m/s or 284 mph. That is faster 40% for the same amount the trains will have to work, but to build all of that infrastructure, spend all the money creating a lower pressure environment and maintain that pressure for thousands of miles is just not worth it. The vacuum tube is just not practical to make.
Edit: If you maintain a reduced pressure and increase speeds about 30% of the speed of sound, the subsonic equations I used start to be less accurate. But in that case drag increases dramatically in transonic and supersonic regimes.
This is the kind of actual discussion that I hope for in these discussions. While many people focus on the dangers of the vacuum tube proposed for the Hyperloop infrastructure, I always wondered about the benefits. It’s not like putting a train in a vacuum will suddenly make it go infinitely fast.
So, the question is how much faster would it go? Once you have that number, you can adjust the car vs plane vs train chart that CityNerd showed off. All it would do is deepen and lengthen the railed transit curve some amount. It would potentially increase the distance two cities could be and still provide a benefit over airplane travel. It’s just a question of how many city pairs it would help to include as a rail option.
Going from 200 mph to 284 mph won’t make that much of a difference. Yes, it’ll open up more city pairs for high speed rail, but when comparing those benefits against the cost of the massive tube construction it’s not going to seriously pencil out as a net benefit.
Here’s the video where CityNerd lays out their reasoning and charts a rough model of where high speed rail is going to be a more reasonable choice for travel based on the distance needed to go: youtu.be/pwgZfZxzuQU?t=477
I think if they are doing a vacuum tube, they should get as close to a vacuum as possible.
I think if the USA is going to spend trillions on rail infrastructure, I think we should start with doubling or tripling the amount of trains on Amtrak first. It’s not as sexy as the Hyperloop, but it would get people riding trains more often
@azimir@Erismi14 I'd be interested in seeing "the cost of building a massive tube" compared to "the cost of building a massive highway".
DOTs across the country have been using phony math to justify ludicrously expensive highway projects for decades -- given a train in a tube would be higher speed and higher throughout, I feel like using their same logic we'd see huge "economic benefits" from connecting two new business centers with a transport mode that allows workers to work in-transit.
I think if we had an economy already built around these tubes it would be much cheaper, but I think that it would still be similar if not more in price as the building of highways.
It is not as easy as building a "bigger oil pipeline and running trains through it. The train moving at high speeds will need a complex and robust system that is continuous inside and outside the tube. The tube will also need ground foundation to handle those forces.
Curves and elevation changes will need to happen at even flatter grades than highways. The higher speeds mean higher acceleration around curves or up inclines. The less sharp turns means more of a reliance on raised structures and tunneling. Good luck on convincing thousands of farmers to put a tube through their property
Maintenance. A highway with a crack in it still works. A highway with a pothole in it still works. Maintenance on that pothole costs $10k USD and the highway is still usable through maintenance. Hyperloop maintenance would not be as cheap, the tube would be shut down before and during maintenance due to repressuring. The tube would need to be vacuumed again.
I’m sure there are other things undiscovered that would be costs as well.
I think the Hyperloop is a cool and shiny idea. In the US I would much prefer reliable and cheap, normal speed rail first, then highspeed, then Hyperloop if we ever get there. I don’t think we should be able to eat our pudding before we eat our meat if that makes sense.
Add to that that the Hyperloop is incompatible with regular rail.
If you build a highspeed rail connection between two cities, you can start by just building highspeed tracks on the straight, empty areas of the connection where you get the biggest benefits, while letting the train run on regular rails in between. So while building the track, the travel time will be gradually reduced as more and more of the track is completed. In the cities themselves, the train can use regular tracks (since highspeed travel probably won’t be a thing there anyway due to space restrictions), and it can also use the regular railway stations. This allows you to directly connect the rail service to other trains without having to build separate stations with potential shuttle services in between.
Richard Branson’s Virgin Hyperloop One is literally a train. They themselves call it a train. I guess the idea is that they’re small individual cars (called pods) instead of a chain of train cars connected together, which seems really energy inefficient.
Elon Musk’s Hyperloop is a train for automobiles, which has all the inefficient downsides of a personal car, with none of the energy benefits of a train. It is the worst of both worlds. And it relies on car infrastructure at both ends, so it will bottleneck just like a highway on/off ramp. Completely nonsensical.
That sounds like a very Muskrat idea. Don’t worry though, he never builds his own ideas. When someone smarter comes along and invents something better, Elongated will buy it and claim to have invented it, just like every single one of his other accomplishments.
Musk “invented” the hyperloop and said he didn’t want to develop it and others should. One of the companies that picked it up was virgin. The car tunnels are the “loop”.
Isn’t Hyperloop just a concept for a vacuum train though? That literally is a form of train, just one that is, at least presently, too impractical and expensive to actually use. Honestly I think the concept has some merits, we just don’t have the technology, logistics or need to have use of it just yet.
I’m skeptical of the idea that the concept, or at least the general concept of a maglev train in a vacuum or low pressure system to enable higher speeds and efficiency, will never ever be realized, because there are any number of future technologies that would make it easier (for instance, significantly better materials would make it easier to build long vacuum chambers, significant advances in automation could increase productivity to the point where society can afford much more expensive projects, and if people ever actually start to build settlements in space, then it’d be really easy to build one on a place like the moon because there’s no need for the huge vacuum chamber. I understand it would take a very long time for enough people to live in such settlements to actually need such things, but someday it could happen.)
Not that I don’t think that it’s being pushed today isnt wishful thinking at best and intentional distraction at worst, but I think the general concept could be sound one day with the right technology
Hyperloop is more of a concept for high-speed trains/pods in a vacuum tube that go between two major cities (in a loop, hyper fast). It got conflated with his bs tunneling project (the tunnels are smaller, that's the only "innovation"), but a Hyperloop would be much more likely to be primarily elevated like a high speed train.
More like a pipe dream with no practical thought put into it that was sold by a conman entirely to derail the planned high speed rail that would have connected SoCal to Seattle.
The end result is a tiny quarter mile tube in a convention centre where you can drive your Tesla in a loop but only like 10 mph and god forbid there’s an emergency like a fire because there’s no emergency exits if you’re stuck behind a burning Tesla.
Actually, maglev trains are slowly becoming practical, and the hyperloop is just a train in a tube with no air. It won’t be something revolutionary, just an even faster high speed train. Of course removing air from a tunnel creates its own problems: What if there is a fire? Normally you could get out into the tunnel, can’t do that with no air.
It is much harder for fire to exist without air. There are some self oxidizing fires, but it should be relatively easy to avoid those materials. For fires inside the vehicle, there are some existing fire protection protocols that could be followed. There have been fires on the International Space Station and they couldn't exactly run outside either.
The ISS isn’t exactly mass transit. In most of those fires, they could evacuate to another area if necessary. That doesn’t work for a train where basically all the space is announced for.
Having multiple, semisolated compartments in a Hyperloop train is entirely reasonable. There's definitely room in a traincar for the occupants of a compartment that's on fire to move to another compartment for emergency purposes.
Evacuation points would be defined every so often (say every few miles) such that the train could come to an emergency stop within one, seal doors on each side and let air in. This would take a few minutes, but so does landing a plane or stopping a high speed train.
Bottom line is that fire safety is, to me at least, an entirely solvable problem. The biggest problem with Hyperloop, I think, is that given the materials for the vacuum sealed tube and the energy required to hold that vacuum, it is just so unlikely to be more efficient than a maglev. For medium distance travel, even standard high speed rail is good enough to replace planes, so we don't need the extra speed for ~500 mile distances. For longer distances where high speed rail is super slow or impossible, such as across continents and oceans the cost of building the vacuum tube will be so costly that it would take something like a complete ban of non-renewable fuels in aircraft for it to be a consideration. Even then, I think it could end up being cheaper to develop and use renewable fuels for aircraft.
Add comment