Not sure if 'Locomotives' is the right place to post this, but it is about haulage of wagons. I'm making a model of an incline into a mine, and I wondered what I should use for the ropes. I was going to use cotton thread.
Perhaps "shirring elastic":
http://www.amazon.co.uk/s/?ie=UTF8&keywords=shirring+elastic&tag=googhydr-21&index=aps&hvadid=11804559234&hvpos=1t1&hvexid=&hvnetw=g&hvrand=9854415691625205566&hvpone=&hvptwo=&hvqmt=e&ref=pd_sl_305o7vnrwn_e (http://www.amazon.co.uk/s/?ie=UTF8&keywords=shirring+elastic&tag=googhydr-21&index=aps&hvadid=11804559234&hvpos=1t1&hvexid=&hvnetw=g&hvrand=9854415691625205566&hvpone=&hvptwo=&hvqmt=e&ref=pd_sl_305o7vnrwn_e)
Perhaps a bit over scale at 0.75 mm diameter.
(I am imagining that it will be under a bit of tension to keep it taught. Whether it will be stiff enough to haul wagons up an incline, I'm not sure.)
Check out JdF's Cliffhanger layout and see what he uses, I seem to remember that he'd tried several types of "rope" but I don't know what he finally decided on!