The UK's first drop lock is due to open next year on the Forth & Clyde canal at Dalmuir, as part of Scotland's £78M Millennium Link project.
The canal was permanently closed to boat traffic at Dalmuir when the Dunbarton road was built in the 1960s, as it restricted headroom to 500m - too low for boats to pass.
The £1.3M drop lock mechanism will lower the water level beneath the road to increase headroom under the bridge to 3m. Lock gates at either side of the road will be left open, but when a boat enters the lock to pass, the gates will close and the 2,000m 3of water inside drained or pumped out. Contractor is RJ McLeod and the consultant is Halcrow.