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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."
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.
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 ..
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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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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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
Won't be under an hour, unless we're pulling .2g or so.
More like 80-90 minutes.
Your point stands, however - it would make a bloody mint if it existed. If only from people who rode it just so they could say they did it....
"I do not agree with what you say, but I will defend to the death your right to say it"
Well, in fairness, the Big Dig is not a good example considering that 2/3 of the money probably ended up in the hands of criminal syndicates of one sort or another. Also, it was built underground below the water table, and required a tunnel six or eight lanes wide - probably an order of magnitude or two more difficult and expensive than a train-size tunnel.
By comparison the City of Portland, Oregon recently completed the 'Big Pipe' projects, digging about 10 miles of tunnel up to 160 feet underground (and under a river) to handle storm runoff. They used 14-foot diameter boring machines and did the whole project for $1.5 billion, which is about $150 million per mile. That cost included all the pumping stations and other costs, not just boring the hole. (See also West Side CSO Tunnel.)
So the cost of drilling a train tunnel, which would fit nicely in a 14 foot diameter tunnel, should be of the same order. Adding maglev or whatnot to make trains actually go would be additional, of course. At $150 million per mile, the 400 miles from SF to LA could be drilled for $60 billion. But you actually need three tunnels - one each way plus a service tunnel (like the Chunnel between UK and France), so call it $180 billion.
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You don't have to guess about the maglev part, because Japan is building an actual long-distance maglev line. Costs seem to be about $200 million / km, but that includes everything, stations, etc (compare the various route choices and note that the construction costs don't vary nearly as much as the distances [that's affected by the amount of tunneling, etc, too, of course]).
We live, as we dream -- alone....
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.