"Fort Augustus Swing Bridge carries the A82 across the Caledonian Canal adjacent to the staircase of locks which lowers the Canal down to Loch Ness. The original timber deck was replaced in 1981 by a steel battle deck; a two metre wide cantilever walkway was also added to the side of the deck at the same time." - Link
NH3709 : Caledonian Canal memorial plaque The poet Robert Southey witnessed the works at Fort Augustus in September 1820, and left an awestruck description of the scale of the construction effort.