In article , Andrew Mawson writes
'When I were a lad' I helped put up a Bailey bridge at a school cadet summer-camp. We built it faster than any of the other squads, but found out why when they tried to drive a three-tonner over it - we'd missed half the pins out, so it promptly collapsed.
Next day's exercise was 'how to get a three-tonner out of a gulley'...