I prefer to live in a frictionless world :) It looks like it was rope on metal (http://jaccuzzi.ch/photos/700/1722_264_03.jpg http://jaccuzzi.ch/photos/700/172

I prefer to live in a frictionless world :) It looks like it was rope on metal (http://jaccuzzi.ch/photos/700/1722_264_03.jpg http://jaccuzzi.ch/photos/700/1722_264_03.jpg) with a coef. of friction of 0.2. My gut says the friction force will be at most half horizontal. That puts friction an order of magnitude lower than T, though that is more than I expected. (edit: damn, it rounds the corner from vertical to past horizontal so my symmetry argument doesn't quite hold.) Apparently the bridge carried cars at one point (http://en.wikipedia.org/wiki/Gueuroz_Bridge http://en.wikipedia.org/wiki/Gueuroz_Bridge) so the wall was rated for vehicle impacts, which is good. Why they went over the top of the walls I don't know, I think they wanted to measure the ropes exactly instead of adjusting it the day of. Like, that was where they drew the line of "unacceptable risk"? I agree a loop through the drain holes would have made their lives easier in a bunch of ways, except the tripping hazard would have made it a very risky project...