[Fury]

ET3 revealed yesterday their big project about new form of transportation, vacuum tubes. Sounds funny, but demonstration actually makes it very reasonable. Reportedly they intend to build 5km long test version by year's end.

[karajorma]

Futurama here we come!

[Dragon]

Well, looks like pneumatic mail is making a comeback, and how! Really, I'm surprised nobody thought of this before. It's gonna go hand in hand with Maglev technology.

[The E]

It's gonna go hand in hand with Maglev technology.

They're already using maglev as their propulsion system. No maglevception is planned.

There is, however, a big problem with this thing. It requires massice infrastructure investments, and there are precisely no governments that fall in the sweet spot of being able to effectively utilize these things, and being willing to make that big an investment. It's a drawback shared by all Maglev systems.

[Fury]

Very true. As far as infrastructure goes, I think they could build these tubes over current railroad network. That way electric network to power the tubes would already be in place and you can use railroad stations for the tubes too. It would also allow trains and tubes to co-exist within practically same space. Subways would be whole lot more difficult though, but you gotta start somewhere.

[Black Wolf]

It's gonna go hand in hand with Maglev technology.

They're already using maglev as their propulsion system. No maglevception is planned.

There is, however, a big problem with this thing. It requires massice infrastructure investments, and there are precisely no governments that fall in the sweet spot of being able to effectively utilize these things, and being willing to make that big an investment. It's a drawback shared by all Maglev systems.

This would be a great solution for the high speed rail they want to build between Melbourne and Sydney. I think it's still in the cost/benefit analysis stage, so there's plenty of potential. Plus China will very likely be interested too.

[karajorma]

China discussed the possibility of a maglev connection between Shanghai and Hangzhou but decided that the cost was too high given that while the maglev runs at a blisteringly fast 430km/h, the standard G-type bullet trains run at a pretty reasonable 350 or so. On a journey that takes an hour on the already developed G trains, it's not worth going to Maglev just to save an extra 10-15 minutes.

[Nuke]

you could probibly mass produce tube sections out of rebar and concrete (and coated in epoxy) on an assembly line. typically maglevs have the magnets on the track while the train just has an aluminum plate underneath it. if you were to flip the concept and build the plates into the tube sections it would make the whole system much cheaper. the cars could actually run on lithium cells, to provide power for the coils and the life support (yea you need that too, humans cant breath vacuum) then maybe you got something. its not the cost of the train that makes it affordable or not, it really comes down to track production costs, so if you can make the track cheap it becomes viable.

[The E]

Yes, of course, and I would think that they've spent a bit of time on optimizing that. Still, their materials say something about a cost of several million per mile of track; given that that price does not include things like right of way agreements or other engineering challenges, it's pretty unlikely that anyone will be able to actually finance a track long enough to be more than a vanity project.

And then there are questions in my mind regarding this system's failure modes. What happens, simply put, if the power goes out? How can passengers evacuate from a stopped car in the middle of the track?

[Black Wolf]

Yes, of course, and I would think that they've spent a bit of time on optimizing that. Still, their materials say something about a cost of several million per mile of track; given that that price does not include things like right of way agreements or other engineering challenges, it's pretty unlikely that anyone will be able to actually finance a track long enough to be more than a vanity project.

And then there are questions in my mind regarding this system's failure modes. What happens, simply put, if the power goes out? How can passengers evacuate from a stopped car in the middle of the track?

I would guess that there would be either air pumps with UPS  every km or so, or there'd be a system where valves needed to be powered up to stay closed, and that power loss would lead to air flooding the tube. Once there's air in there, then it becomes no more of a problem than a train stopping in a tunnel. Access hatches every 5km or so and you're fine.

As for the cost, the very cheapest railway already costs at least a couple of million per km - even single lane highways cost about that much. This system would be more expensive, nut not vastly so I suspect.

[Luis Dias]

Musk is gonna talk about his Hyperloop thing in 12th august. Coincidence?

[Dragon]

As for the cost, the very cheapest railway already costs at least a couple of million per km - even single lane highways cost about that much. This system would be more expensive, nut not vastly so I suspect.

Don't forget you also have to power the thing, maintain the magnets (necessary for maglev to work) and the components themselves are very expensive. Not to mention you can't use the "wait until somebody important falls into the hole, then fill it with gravel and call it a day" road repair model with a vacuum tube. Those things need a lot of maintenance to ensure the tube is working smoothly, since there's relatively little tolerance to damage. A train will not care about a minor fouling in the tracks (passengers would, but it's not like it matters to anybody...), a car could go around a hole or drive through it slowly, but if a vacuum tube springs a leak, it needs to be fixed quickly, or it'd expand and could even disable the line.

And then there are questions in my mind regarding this system's failure modes. What happens, simply put, if the power goes out? How can passengers evacuate from a stopped car in the middle of the track?

That's one thing that would have to be ironed out. Not only power failure (that's easy enough), but also containment failure of the train car or the pipes. When talking huge volumes of vacuum, there's plenty of things that could go wrong.

[The E]

A train will not care about a minor fouling in the tracks (passengers would, but it's not like it matters to anybody...)

It's maglev. It doesn't care how rough the track is.

[Dragon]

Track itself? No. But I probably wouldn't want to be riding it when one of the magnets quenches. Or when the tube springs a leak. My point was that you might put off fixing a foul rail, but not a leak or magnet quench in a vacuum tube.

[perihelion]

@The E, I believe he was comparing the relative level of damage tolerance inherent in railway lines versus this vacuum tube system.  A minor leak turns into a huge deal in very little time.  The nature of seals is that once they start to leak, the very process of leaking causes additional (and accelerated) damage which causes them to leak faster.  How many seals do you think you'd need on a system like this, even on a relatively short run from Jersey to NY?

And then how do you replace / repair those seals without taking the entire line down in the process?

On a rail line, the rest of the line can keep on working.  Unless you have a lot of redundant airlocks in the line (EXPENSIVE!!!), that would not be the case in the vacuum line system.

I don't mean to be a negative Nancy; I'd really like to see something like this implemented.  But the "what could possibly go wrong" part of my brain is just doing somersaults.  What would they use for the tube?  Glass?  [shudder]  What if there's a hail-storm?  Some transparent polymer?  All of the ones I know of are subject to problems from prolonged exposure to sunlight.  I suppose it doesn't really need to be transparent like it is shown in the video.  That opens up a lot more robust possibilities.

EDIT: Ninja'd

[The E]

They've already stated in their materials that they plan on using metal for the tubes.

And yeah, there are so many pitfalls with this design, it's not funny. More traditional designs like Transrapid have their own issues, but at least their failure modes seem rather benign and easy to deal with barring catastrophic damage to the track.

[Dragon]

Even in case of catastrophic damage to the track, a Transrapid would, at worst just derail (and in most cases, it'd drop on the track and probably simply stop). In case of catastrophic damage to a vacuum tube system, you're dealing with a violent, devastating implosion that would most likely total the entire track and obliterate whatever's inside.

Ah, I also forgot to mention that you can't run multiple trains inside a single tube using this system. Overall, it seems that it'd be more suited for urban communication than for long distances. Metro, for example, wouldn't mind only running one car on a single line (at least if it's short) and an underground tube would've much lower risk of being breached. It could also be controlled from a central pump station inside the city, somewhat simplifying the system.