At 03:19 AM 4/26/01 -0700, you wrote:
>Perhaps we should resurrect the old proposals for underground tubes
>linking major cities. The tubes are denuded of as much air as possible
>to lower resistance and mag-leve trains are run in them. If it could be
>made to work the cost after building the system would be substantially
>less per passenger/mile and the velocity attained would be much higher.
>Any thoughts on what (besides all the environmental roadblocks) is wrong
>with such an idea?
It's a great idea, but for a few problems:
1. Tunneling costs at present are very high, and fro economy, the tunnel
would have to be virtually leakproof to prevent unnecessary pumping losses.
2. The "trains" would need life support systems akin to spacecraft, just in
case of a stranded train (system failure).
Once the system is built, if properly designed, the cost of energy needed
to transport a train would be tiny, and much of the energy would be
recovered in slowing the train for the next station.
The ultimate system would run at orbital speeds in the tunnel - zero
gravity! - and would be able to circumnavigate the planet in about an hour.
A realistic system would go slower, since the tunnel would probably not
follow a nice orbital curve relative to the center of mass of the planet.
ZG might be a selling point for the adventurous...
I have heard proposals of tunnels driven on chords through the crust - this
makes for the shortest ride, but now the intercontinental tunnels are deep
enough that materials science would need a big boost to handle the
pressures and temperatures. A real honest to goodness force field would be
nice for this!
The problems of transiting plate boundaries and faults would be solved with
huge caverns, with the tunnel set up to be flexible enough to survive
As civil engineering, this would make the huge dams currently under
construction in China look like sand box creations...
Environmentally, the only problem I see is disposal of the tunnel tailings,
which might be similar to mine tailings, depending on what rocks the tunnel
goes through. It sure can't have the impact a standard road or railroad
would! The only visible signs of the system would be the terminals and an
occasional power station - these might well be underground, too, especially
if the tunnel goes really deep.
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