Nice detailed write-up. Couple additional details worthy of discussion: 1) Covers also can have hinges, so training of personal may be not even required. 2)

Nice detailed write-up. Couple additional details worthy of discussion: 1) Covers also can have hinges, so training of personal may be not even required. 2) It's unclear that round cross-section is the most convenient for humans to climb, after all humans in horizontal cross-section are like elongated ovals, so rectangular shape could be better. :)