On Marinus, one of the keys to the Conscience of Marinus was kept in a room which could only be accessed by a rope bridge. Vasor tried to strand Susan Foreman, Ian Chesterton, Barbara Wright and Altos there by untying one end of the bridge. (TV: "The Snows of Terror")
River Song and the Eleventh Doctor once crossed a rope bridge to escape from Zygons. (PROSE: Dr Eleventh)