I'm betting there was a safer way available that involved quite a bit of walking. Construction workers can be very resourceful, especially at quitin' time.
My brother worked his way through college building liquid natural gas tankers at the Quincy ship yard outside Boston. The ships were finished in a huge dry dock, with about a hundred foot drop from the deck to the bottom. His first day on the job, the whistle blew and he headed for the gangway, about eight hundred feet away. The other guys all headed directly for the edge, where they threw a two-by-twelve across the chasm and proceeded to walk across to the dock.
About ten days later he got tired of the long walk and tired of being laughed at, so he decided to "walk the plank". That's the day he discovered that it was tradition, when a new guy crossed for the first time, to wait until he got half way across and then start bouncing the plank.