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https://en.wikipedia.org/wiki/Material_ropeway is an elegant technology, popular around the 18th century, that transports bulky cargo along highly-trafficked routes with minimal energy requirements.

The longest I could find reference to is 96km long. I presume (am I right?) that the limiting factor here is the weight of the cable: a 96km-long steel cable is very heavy, and requires a sturdy structure to support it.

If very light, very strong cables could be made of an advanced material, could aerial cableways be made to stretch from New York to Los Angeles?

Thanks worldbuilders.

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    $\begingroup$ I suspect there are other constraints that also limit the usefulness of such a system for transportation of mass quantities of goods. For starters, these were often used to transport homogenous packets of goods long distances without stops in the middle, and it wasn't entirely clear what the energy investment was - if it became more expensive over a distance, or less; if it needed counterbalances, how vulnerable it would be to disruption (earthquakes, tornados, floods undermining supports, etc.). This needs some more citation to flesh out the details, but it's an interesting question! $\endgroup$
    – DWKraus
    Sep 11, 2021 at 15:16

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Ski lifts would probably be the most familiar example of this technology.

You're wrong about cable weight being a major limiting factor. The important factors are the distance between supports and drive points. There are three significant forces acting on a system:

  1. The weight of cable and cargo
  2. The pulling force exerted on the cable
  3. Side loads produced by winds &c

Simplistically, the system only has to support the weight of cable & cargo between any two support towers, so that can be easily dealt with by placing towers fairly close together. This is something you will generally want to do anyway, for terrain clearance and to reduce wind loads. (Note how ski lifts get shut down in higher winds.)

Pulling force can be dealt with by having multiple drive points along the length of the cableway. For a long-distance system, you'd probably want multiple loops anyway, so you could maintain & repair segments without shutting down the whole system.

Maintenance is really going to become a major issue here, especially wear on the cables. How well do carbon nanotubes deal with the friction of going over the sheave wheels and around the bullwheels? Steel on steel wears pretty well. Compare railroad tracks & wheels to roads and car tires.

Then there's the issue of failure. Cable breaks under tension are not something you want to be anywhere near.

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