Re: Evacuated Tube Transport

Thomas Barclay schrieb:

> 3. On a vacuum moon or something, the risk of 
> penetration that is posed by external 
> atmospheric pressure goes away.

Right. But then you don't need to build a tunnel to reduce air
resistance. As far as I can see, reducing air resistance is the main
advantage of the proposed tunnel scheme.

> 4. It has traditionally been far more efficient to 
> move mass by rail than by truck or plane (by a 
> long shot) - and this method looks even more 
> energy efficient. If your concern isn't the danger 
> to the apparatus, but the cost efficiency of the 
> system, this system may move KGs (and 
> conventional rail definitely does) far cheaper 
> across continental distances than your air-net. 

You didn't mention two factors: 

* the speed of the transport. Basically, you can move stuff cheaply and
slowly or fast and expensively. Conventional rail is very slow - slower
than trucks over almost any distance. Depending on your specific goods
and the costs of delays in delivery, it can be more profitable to move
stuff by air.

* the cost of investment, which has to be offset by the income from the
transports. If the tunneling is so expensive that 90% of the transport
price goes for servicing the debt from the original investment, it
won't help if actually operating the train costs next to nothing.

A specific example of this is the Transrapid Maglev train project in
Germany. Nifty technology, but the cost of building the track was such
that it could not be operated profitably even under very optimistic
assumptions.

> I'm not saying this is viable any more than a 
> space elevator is (both are contestible points). 
> But both also make for some interesting 
> chrome for a setting (beanstalk anchor would 
> be an interesting target point for a DS2 or SG2 
> mission..... and so would a tube-train line. 

Definitely :-)

Greetings
Karl Heinz