It may take a few attempts, but this article on the longest cableway in the Andes is worth a read.
  For additional information on cableways (also called ropeways), see this informative site.
Well for one thing, the shape of the cable has changed.  If we assume that the cars are equally spaced and the cable sags at a 15 degree angle, what do you think the tension force will be?  2P?  3P?  The actual answer is closer to 4P.   It is the tension strength of steel that makes cableways practical.

Now what if we continued to add cars to the cable?  Our towers would have to be strengthened and our cable would grow larger.  How about an example?