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Why Ultra-Efficient 4,000 mph Vacuum-Tube Trains Aren't Being Built
cylonlover writes "In the 1800s, when pneumatic tubes shot telegrams and small items all around buildings and sometimes small cities, the future of mass transit seemed clear: we'd be firing people around through these sealed tubes at high speeds. And it turns out we've got the technology to do that today – mag-lev rail lines remove all rolling friction from the energy equation for a train, and accelerating them through a vacuum tunnel can eliminate wind resistance to the point where it's theoretically possible to reach blistering speeds over 4,000 mph (6,437 km/h) using a fraction of the energy an airliner uses – and recapturing a lot of that energy upon deceleration. Ultra-fast, high efficiency ground transport is technologically within reach – so why isn't anybody building it? This article looks into some of the problems."
Yes, like aeroplanes and submarines...
If you don't reach for the stars you will never get there, if you try, you might.
Who wants to accept the liability if passengers/surrounding objects get turned into goo when a tiny defect causes the 4000 mph object to decelerate in a not-quite-so-planned manner?
When the British did it they had hella mechanical problems. The smallest glitch with a seal and suddenly your trains aren't moving nearly as fast anymore. You'd have to build two tunnels: the vacuum tunnel for the train, and then a slightly larger outer tunnel that allows for service and leak detection.
this idea sucks
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
Use it for cargo first, and if there are no problems we can start using it for passengers. But the cost is a big obstacle.
Wake me up when someone actually manages to build a tunnel anywhere near that size that's vacuum tight and has a realistic notion of what size and number of vacuum pumps would be required to keep a high enough vacuum in it. Oh, and handling the exterior pressure loading without risk of accidental implosion would be nice. ;)
The other problem which is less trivial than it might seem is how to get people and cargo (and possibly vehicles) onto and off of these trains without breaking the vacuum .. really big airlocks at the stations maybe? .. and how to evacuate one of these safely in case of an emergency on the main line ..
They do have a warmer more 'natural' sound
“He’s not deformed, he’s just drunk!”
I'm not half as think as you drunk I am.
"Kill 'em all and let Root sort 'em out"
It's the mile-low club.
"Kill 'em all and let Root sort 'em out"
Someday maybe the Japanese can figure out how to build a bullet train in an earthquake zone.
Because the simple-minded mythology that people create for themselves is just that: feel-good pseudo-engineering that makes no sense whatsoever.
For an AC that was a brilliant post. However a little brief. As a "real engineer" who can do estimation and think thru technical problems the biggest problem is the vacuum tube is a waste of money and time and land. For a much smaller scale example you could reduce the "indicated air speed" as a pilot would call it of the TGV in France merely by installing gigawatts worth of walmart kitchen fans pointing such that the train gets a nice tailwind. However if you run the numbers it turns out you can get the same performance increase with merely megawatts of extra train power. Similarly, you could invest in terawatts of distributed vacuum pumps, but it turns out you can go just as fast merely by using gigawatts of train power...
Generally speaking in engineering making the immense part more expensive to make the little part cheaper doesn't pay off, for sufficient value of immense. For example, it turns out to be way the heck cheaper to make a long distance transmission line HVDC than to upgrade every tower long the route higher dielectric strength and taller and bigger footings etc etc. To a crude first approximation this is why sea transport is cheaper per ton-mile than train transport. Another example in the US outside hyperurbanized areas its cheaper to buy each user a taxi and taxi driver than to build passenger rail. I like trains and I like riding in trains but even I realize they're an economic disaster.
In fact it turns out to be cheaper to build a self-levitating and self propelling vehicle than to build a really long and terribly complicated track. I think I shall call my new invention the aeroplane.
The other problem is economic. Any 4000 MPH solution is terrifyingly expensive, so even zero interest expense makes it horrendously expensive. If you can get it cheaper than merely hiring someone far away, or booting up a PC running skype... For example, even during the Concorde era it didn't make financial sense to ship a salesman between NYC and London on the Concorde, it turns out to be cheaper to simply open a sales office in both cities and hire staff in each. Somehow this tremendously more expensive solution is supposed to work even better under conditions where cheaper solutions miserably failed?
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
XKCD reference
Help fight poverty: Punch a poor person.
It's the mile-low club.
Technically its the "mile per second club".
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
Trains are an economic disaster in the US, and it is not for any sort of engineering reason (you can look at pretty much any other industrialized modern country in the world and see that trains actually work out pretty damn well).
Trains are an economic bonanza in the US. Freight trains are still trains.
Limit your comments to passenger trains, and you might think it is true. Then you realize they're competition g with heavily subsidized highways.
Not necessarily. Bear in mind that when you're talking about accelerating to 4,000 MPH, you're limited to very-long-distance travel. Bear in mind, we're talking about Los Angeles to New York City in a little over half an hour. This wouldn't replace subways, but rather would replace jets and trains.
Also, when public transit is used by people who can afford cars, it is usually because driving is unholy in those cities. It would be more precise to say that public transit doesn't work unless the normal road system is hopelessly broken, which is not the case in the suburbs.
Check out my sci-fi/humor trilogy at PatriotsBooks.
Vertical travel is a very different proposition. Compare the energy usage for a person standing at the top of the Empire State Building and a person standing in a helicopter hovering a few metres away. Both are at the same height, but one is having to use fuel (in quite significant amounts) just to stay in the same place. Now have the man in the building go up and down the stairs for an hour and have the helicopter maintain the same height as him. At the end, compare their energy usage.
In contrast, for something like a train the majority of the energy is used in acceleration. Reducing air resistance and rolling resistance give some benefits, but it's not huge. The advantage of the hypothetical maglev vacuum train is that it can keep accelerating for as long as it wants (air resistance increases with speed). This isn't really useful for most trains, although it would be useful for something like a transatlantic or transpacific railway where you'd have a long distance and nowhere where you might want to stop on the way.
For reaching orbit, a space elevator means you don't need to carry as much fuel. Over 90% of the mass of a rocket going into orbit is the fuel required to carry the fuel into orbit. Take that away, and you've made a huge saving. If you can power the climber from the ground, it's even better. Acceleration is also an issue. A rocket must accelerate at more than 1g just to move upwards. Because of this, it must accelerate hard so that it doesn't run out of fuel just maintaining the 1g needed to stay in the same place. A climber can maintain a constant speed or a slow acceleration.
The main reason we haven't built a space elevator is that we've only recently made materials in the lab that are (probably) strong enough to be used for the tether, if we could work out how to mass produce them.
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Airlocks? Docking a train in a near-vacuum tunnel to a station has to be considerably easier than docking two spacecraft in a vacuum.
At those speeds, flames would be the least of your worries. a 20,000kg train at 6400kph carries the kinetic energy of a 8,000kg of TNT (31GJ). It would take 3 minutes to get to that speed with a constant 1G acceleration and require a 17MW output engine, and would travel 160km while getting up to speed.
The point is things like planes weren't possible until gasoline engines, very quickly powered flight went from impossible to possible due to one technology and some smart people.
So:
1. Don't stop dreaming
2. Your Religion of Pessimism is just as bad, so STFU
Trains work in the US when shipping freight. The work for passengers in the northeast. However, cars are far more convenient everywhere else.
Case study:
Trip to Norfolk, VA from NYC area.
Fly: ~$300 per person round trip. You get one carry-on bag per person. 1.5 hrs each way + 4 hrs of transit/wait time.
Train: ~$250 per person round trip. You can carry more on. 8 hrs each way + 2 hrs of transit/wait time.
Car: ~$75 per car round trip. You can carry even more. 6 hrs each way; no wait time.
Now, if I didn't already have a car with sunken capital costs, then there is an argument. But even then, I would rent a car. Either way, it is cheaper and takes less time to drive than take the train.
In contrast, it would be crazy to drive into NYC when the train station is right next to where I am. Flight is almost always better if time is a factor.
And don't tell me "it's different in Europe". I was in Germany. I can drive from Munich to Berlin faster than the ICE train. And the train ride costs $150+ each way per person.
Outside of heavily subsidized metro area trains, I have not seen a train compete with the cost, let alone the time and convenience of driving alone. When you add a 2nd person, it just gets crazy to take a train.
Hah. I rode the train daily with Goldman Sachs guys who lived in houses I can barely *dream* of owning. The train was more convenient from Summit NJ to Manhattan than any other kind of transport, including helicopters (according to one of the guys, after his second paper-bag beer one Friday*). Apparently helicopter transport to NYC is a pain in the ass, because the helipads are not conveniently located -- either on the departing side or the arriving side.
*So every Friday, four GS guys who always sat in the same spot, would have beers on the train. One of the guys retired, and they need a fourth to occupy the seats -- they didn't want some random person sitting with them. They asked me to sit with them, it lasted about two months until circumstances made it better for me to commute by bus instead of train. These guys would pound a beer (or two) in Penn Station waiting for their train, then drink another one (or two) on the 40-minute train ride home... they jokingly said it was the ammunition they needed to deal with their wives for an entire weekend.
But I digress...
If you take the Morris & Essex express into Hoboken or NY, which skips all or almost all the stops in Essex county, you'd believe that it's only the *wealthy* who take trains.
"Trolls they were, but filled with the evil will of their master: a fell race..." -- J.R.R. Tolkien on Olog-hai
My favorite thing about slashdot is all the people that assume that if they can't solve a problem by the time they post a comment, the problem is unsolvable.
Have you ever heard of airlocks?
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Trains only work when government subsidizes them. FOR the cost of the new California High Speed Rail, that won't actually be useful until just before it is completed (i.e. nobody could ride it anywhere useful), you could give every man, woman and child a whole bunch of passes on Airlines from more places in the state than the CA HSR would actually go. And it would take less time to travel to said places. And cheaper.
The way I explain it, we already have HSR, they are called Airplanes. HSR was designed for one thing only, to curry favor with the Unions that will build and run them. It is a Union Make Work Program .
Here's the math ...
Cost of the HSR system (current est) 65,400,000,000 (this is nearly 50% more than the ballot said it would be) It will be much higher when all is said and done.
Actual Population of California 38,000,000
Short versions of the numbers 65,400 / 38 = $1721 per man/woman/child
Cost of a plane ticket $68-$250 one way. That is SEVEN free (high cost) tickets per man woman and child in CA. THIS does not count the actual cost of the ticket to ride the train. And all the projections, even from the Rail Authority, tell us that the cost will have to be continually underwritten by the tax payers.
I have yet to have a person make any sort of reasonable argument why we should spend that kind of money in a state that is going broke.
Agent K: A *person* is smart. People are dumb, stupid, panicky animals, and you know it.
You guys always point to reality...as a defense for your delirious mental illness about space. Doesn't work that way.
Ummm...yeah. What do you want people to point to instead? The Starship Enterprise? That's kind of the the point. You say that ${futuristicConcept} can't be done because of insurmountable technical obstacles. Other people point to ${formerFuturisticConceptThatIsNowReality} as a counter-example of something once thought impossible, but now taken for granted. For years, people said it was impossible to fly in a heavier-than-air, powered aircraft...then our friends Wilbur and Orville (or Glen Curtiss, depending upon who's revisionist history you choose to subscribe) did it. People thought that rockets couldn't "fly" in a vacuum because there was "nothing to push against." Then the Russians launched Sputnik. All (or at least "many") experts said we will never exceed the speed of sound...then Gen. Yeager did it. The point of all of these examples is that people thought a number of various things were impossible...until someone figured out a way to get around the obstacles that people thought were "insurmountable." Griping that pointing "to reality" to argue that things are only impossible until someone accomplishes those things is, in fact, the way it works.
Those things were built because they were able to build them...
True statement is true, yes. Your point?
What you are blatantly ignoring is that people didn't think those things were possible -- exactly as you don't think various things are possible now. The problem wasn't that things were intrinsically impossible; it's that people were approaching the problem from pre-conceived notions based upon the limitations of existing technology. In what way are the things you currently say are impossible merely limited by our current understanding of physics? This may come as a shock to you, but...(wait for it)...we don't know EVERYTHING yet. Therefore, we can't predict what "impossible" things will become possible when some "Eureka!!!" moment shows that something we all thought we understood gets shattered wide open by a new discovery. When we get that insight, things that we thought were impossible might suddenly become trivial.
MCSE? No, sir...I don't do Windows. Yes, I am an idealist. What's your point?
That is not the same. If you start walking while on the train you give the train a negative impulse, which is decelerating it. You only don't feel it because the train is much heavier than you.
If you planned ahead, and had the relevant travel card, that price goes down to EUR79 (USD100).
That journey is a little over 6.5 hours on the train. You'd be lucky to do it under 6 hours driving, factoring in relevant breaks and depending on where in each city your arrival and departure point was. If I had anything to do at the other end, I know I'd much rather travel by train than bust my butt driving.
I regularly catch a tran from Vienna to Graz in Austria. The cost is around EUR18 one way, with discount card. The journey takes 2.5 hours by train, and maybe 2 hours by car, depending on the traffic. On the train I can read, work on my laptop, sleep, walk around, go to the dining car etc. It's a much more pleasant way to travel.
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First, airlocks used in space are used a few dozen times at most before being completely overhauled. The docking connector on a train like this would get more than that much use in a single day, probably in a single morning.
If you're thinking of airlocks, then you'd have to depressurise and repressurise the train at every station. If you actually mean a tube connected to equal pressures outside of the tube and inside the train, then you're assuming that the seal of something that can be attached and detached, can handle one side moving as the train bounces up and down slightly as people step on and off, and still will have zero leakage.
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And don't tell me "it's different in Europe". I was in Germany. I can drive from Munich to Berlin faster than the ICE train. And the train ride costs $150+ each way per person.
Berlin-Munich costs 44 Euros each way (you have to buy the ticket a few weeks in advance though), and takes 6 hours. Driving takes the same amount of time, and will cost you at least 50 Euros in gas (600 km * 5l/100km * 1.65 Eu/l = 49.5 ~ and that's a pretty efficient vehicle - you won't get that efficiency doing 160 on the autobahn). So you're just plain wrong. Not to mention, many routes are much faster than a car; Frankfurt - Gottingen takes 1h40m on the ICE and 2h30m by car.
You can't look at the "in station" ticket prices, that's just ridiculous... have you looked at the price of airplane tickets if you buy them at the airport??
-- Let us endeavor so to live that when we pass even the undertaker shall be sorry. -- M. Twain
When folks talk about Amtrak, one of the first comments is that it is subsidized. It is, to the tune of 2.6B a year at the current moment.
We spend approximately $150B a year in state and federal money on highway construction and maintenance.
We spend approximately $16B a year operating the FAA and airports, about 3.5B of which is directly spent on facilities construction and maintenance.
All transportation is subsidized. Cost per passenger mile, cost per trip, or other similar metrics are a far better measurement of financial performance. Passenger fairs are also a very interesting thing to look at, if the same subsidy for rail and airports resulted in fares that were 50% less for rail travelers that may be a better subsidy.
The problem in the US with rail is really simple to boil down. Congress mandates Amtrak serve underserved and out of the way communities. Greenwood Mississippi has Amtrak service because the government said they must go there, not because it is the best route, or the most profitable one. At the same time Congress wants Amtrak to be profitable. That's a combo that doesn't work. It could be a profitable service by aligning routes with where people wanted to go, and dumping unprofitable ones. It could serve underserved communities with a subsidy. It can't do both at the same time.
High speed rail is a long term investment problem in the US, and a problem of our red-tape with building things. The transcontinental railroad was built in 6 years, largely with hand labor. California's high speed line is estimated to connect San Francisco to LA by 2030, 18 years from now. Much of this is the ever evil "regulation", however much of that derided regulation is stuff the people voted for in the first place so we don't destroy our environment, and so on. Much of it is time taken up with legal challenges, large and small, wasting time and money in court. We have to take a hard look at this sort of problem, the US is now building infrastructure at a much slower rate than most other western countries, and that's not a way to stay ahead. We can't just throw out the regulations, that will not leave a functioning society, but we need to streamline many of these processes.
Trains can work just fine in the US, and they do in fact operate profitably in several locations today.