Here in the U.P. there used to be many copper mines and related industry. In the town I called home were several mills, with a 16" pipe running from one mill to another. The pipe carried steam, I think, was covered with an inch and a half of Aspestos with a layer of tar painted over that. While we also "walked the rails" as future circus performers and without having read Nietsche, we also found time to "walk the pipe" that varied in elevation above the ground from one foot to 15-20'.
However, we never met the three bears coming the other way.