ETT

KHR said:

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.

[Tomb] On a vaccuum plantoid like our moon, it might offer dust 
protection for the mechanism. 

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.

[Tomb] Really? I'd say that depends a lot on your situation. Take the 
early Canadian Prairies. Trucks didn't really have too many roads and 
the train could get going a fair clip. 

[Tomb] Some goods have time-to-deliver issues that make air viable. 
For things that do not, sea or rail transport over long distances are 
cheaper. 

[Tomb] The majority of goods in the world are moved by sea. It is by 
far the largest total tonnage. I think you'll find rail is #2. 

* 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.

[Tomb] What about an external tube structure? Not necessary to incur 
tunneling expenses. What if I can tunnel very much more cheaply than 
current tech? 

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.

[Tomb] Given current tech. Given some advances, maybe that 
changes.....