Can you imagine what would happen, though, if there was a collision at those speeds? One shudders to think of it, even.
Of course, the Mormons have already dug the tunnel, and they use it to smuggle polygamous brides from London to Utah… 
Magnetically decelerating the train at the end can return a hefty fraction of the energy imparted at the start to get it moving. Much like the new-fangled hybrid cars with regenerative braking.
Assuming laboratory-quality efficiencies, you might get 90% of the startup energy back out at the end, leaving only 10% as a net cost, plus the energy to overcome frictional losses along the way. Ditto for any uphill/downhill; the trains sliding downhill are imparting energy into the system which is drawn off by trains pushing uphill.
Having a near-vacuum for a running environment, and basing everything on magnetics offers some different energy tradeoffs from the typical vehicle-with-separate-engine-and-friction-brakes-and-air-drag model we’re used to encountering.
Overall, IMHO the whole idea is a financial failure. For any given level of technology, we can always find better ways to invest our money for a more certain and eariler return. So those other ways get backed / built / marketed and this one will still be appearing in breathless Someday We’ll Be … articles in Popular Science 2050.
Fixed point-to-point transportation systems are very 1800s. I don’t see them coming back.
I think looking at this as a means of people-transport is off-target. Wouldn’t the shipping industry (or at least a new shipping industry) jump all over this? What about FedEx? I think I could get a heck of a lot more money transporting a train car full of steel or priority packages than I could for transporting a train car full of people.
I think it’s exactly the right comparison, for a reason that I don’t think has been fully articulated here: Nobody’s clamoring for a faster method of transatlantic travel.
I am not a transportation engineer, but it would seem to me that one of the fundamental lessons from history is that the major advances have been in making transportation more affordable.
For example, to get from Manhattan to the airport in LaGuardia, you can take a subway/bus for $2 and get there in 45 minutes. A cab will take about 25 minutes and cost about $25. Or you can get there in 10 minutes by helicopter, but it costs about $500 a head. The last option just doesn’t make sense for very many people.
The idea that superfast transportation would be appealing for cargo and feright doesn’t make sense to me. I can’t think of any practical applications, any companies or products that would benefit from this.
It’s afforability of travel that is the important barrier, not the time between distances. A trip from NYC to London for $99… now there’s somethign to get excited about.
Regenerative braking may recoup some of the energy spent on accelerating the vehicle, but MagLev vehicles require quite a bit of juice just to keep them levitated against the force of gravity - it’s going to be expensive to run whatever you do.
Did we address the issue of crossing tectonic fault lines yet?
I’m not so sure. The magnets aren’t doing any work, no more than my desk is doing to keep my monitor 4 ft off the ground. The Japanese maglev design uses superconducting coils for levitation, and I don’t think you need to replenish the current in the coil. Of course the refrigeration equipment consumes quite a bit of power.
I thought we were talking about submerged floating tunnels?
I think the strongest argument against it is that, as already pointed out, America and Europe aren’t compact destinations that can be serviced by one tunnel. At least there is a train network in the European side, but there’s no high-speed rail network to hook up with the tunnel on the American side. I live in Alabama; am I supposed to fly to NYC (most likely via Atlanta) and then board the trans-Atlantic maglev? I might as well fly straight from Atlanta to Frankfurt (or wherever my final destination is).
You’ve obviously put more thought into this than I have. But what about this concern: electrical resistance. Any time you pass electric current through a wire, a small amount of the energy is lost as heat. For a short distance, like between the wall outlet and my computer, this is insignificant. But over a distance of thousands of miles, I’d imagine that energy loss due to electrical resistance would be a big problem. Wouldn’t you need one or more “booster stations” out at sea to make up for energy loss? If this is the case, then the only feasible source of power that I can imagine would be a nuclear reactor, unless we’re going to assume cold fusion or some other futuristic bit of Treknology.
Also, once the vacuum is established, you’d have to work to maintain it. After all, you’re going to be breaching the tube to insert people and things, and then take them out again. Presumably, you’d use some sort of airlock to access the train, but inevitably there would be some leakage. Plus, there would probably be a maintenance tunnel running alongside the train tunnel, with access doors every so often. More opportunities for air infiltration. Over time, the quality of the vacuum will degrade, so you’ll need to keep pumping the air out again.
Also, if we need booster stations (as mentioned above) then we need to have people stationed out there, and we’ll have to set up a kind of undersea colony for the workers. Actually, we’ll probably want the undersea colonies even if we don’t need booster stations. After all, if a train breaks down over the mid-Atlantic Ridge, it would help if the nearest rescue personnel weren’t all the way back in London. It would also make maintenance easier if the people were more “local.”
None of these problems are insurmountable, but I’m with BobLibDem; I can’t see this project surviving a cost-benefit analysis.
And I haven’t even addressed the issue of security yet. How are you going to keep the tunnel safe from terrorists? It’s thousands of miles long, and most of it is in international waters. All a terrorist would need is a yacht and some WW2-era depth charges to cause us a world of trouble.
No, and that’s yet another problem. Due to plate tectonics, New York and London are slowly moving apart. We’d need to have the ability to lengthen the tunnel in the middle. I have no idea how you might do this.
Easy enough: Build more onto one end, and re-anchor the anchor points between there and the Mid Atlantic Ridge. Construction allows for expansion and contraction of materials all the time. This is just an extreme case.
Anyone know how tectonic drift affected the various transatlantic cables?
They are not pulled tight. They are laid with enough slack so they lay flat over any roughness on the sea floor, and that slack is more than enough to accommodate plate movements.
Over the workable life of the tunnel (between major repairs), the change in length due to tectonic plate shift would be significantly less than the material expansion/shrinkage due to seasonal temperature changes, wouldn’t it?
It seems to me that the floating tunnel must be flexible, it just is not possible to build somethaing that is long and stiff.
So now, we have a bouyant tunnel and a very heavy train passing though it. Wherever the tain is, the tunnel will flex downwards. The train will expend a great deal of power as it constantly has to climb out of the dip that its own weight has caused.
The only ways to mitigate this effect would be to make the tunnel so bouyant that it hardly notices the presence of a train - in which case the tunnel would have to be huge. Or, the tunnel would have to be sufficiently stiff to spread the weight of the train over a large length of tunnel - in which case the tunnel would be heavy.
I am sure we can all think of reasons why this is a non-starter.
If I am going to travel in a vacuum I would prefer a sub-orbital hop.
Thousands upon thousands of air travellers seem to think travelling between New York and London is worth it.
What’s wrong with oil or coal? A nuclear reactor would make sense (no neighbors to complain, plenty of cooling water available) but there’s no reason you can’t send an occasional oil tanker to fuel the booster stations.
That’s true, you’ll need pumps at regular intervals. But it doesn’t have to be ultra-high vacuum. I think it would be practical.
Or above-sea. The tunnel doesn’t have to be deep, after all - just deep enough that the largest ships won’t hit them. The oil industry has plenty of experience building floating or anchored structures in the middle of the ocean.
Not necessarily. The tunnel could be anchored to the bottom with cables. If the tunnel+train is positively buoyant (which shouldn’t be too difficult), the cable remains taut when the train passees through. The tunnel wouldn’t move down at all.
As for tectonic movement and thermal expansion, all you need is a few flexible joints in the tunnel. An airtight metal bellows isn’t difficult to make. You see them on many vacuum chambers.