Dr Kerry Rodgers ruminates upon revolutionary engineering in central Scotland
Tucked away in Bonnie Scotland, north-east of Glasgow, is one of the great civil engineering feats of the 21st century – the Falkirk Wheel, the only rotating boat lift of its kind in the world.
It represents a solution of a problem British Waterways were stuck with at the turn of the Millennium. British Waterways had been anxious to breathe new life into the canals of central Scotland. As part of their £84.5 million refit of the system, they wanted to re-connect Glasgow with Edinburgh at Falkirk.
Prior to World War II a flight of 11 locks at Falkirk had linked the Forth and Clyde Canal to the Union Canal.
These locks negotiated the 35m height difference across a distance of 1.5km. They had been dismantled and filled-in in 1933.
The Falkirk Wheel was the winning design for a lock to re-establish that link.
Archimedes in action
The wheel consists of two diametrically opposed, water-filled caissons each of which can contain up to four 20m long boats. When the lock gates are closed, the caissons rotate about a central axis. The gates then re-open and the boats can continue on, having been moved 35m vertically.
For those who have forgotten their high school physics, Archimedes insists that the mass of a boat displaces a proportional volume of water. Consequently, the total weight of a caisson will always be the same whether filled only with water or with 600 tonnes of barges. Hence both sides of the wheel will always be in balance.
The upshot is that the entire 600 tonne mass of water and steel requires the input of only 1.5kW to rotate it through 180° in less than four minutes.
The revolutionary concept of the Wheel represents the joint efforts of contractorMorrison-Bachy-Soletanche along with specialists from Ove Arup Consultants, Butterley Engineering and Scotland-based RMJM architects.
The 1200 tonnes of steel were preassembled by Butterleys in Derbyshire to ensure the final fit would be glitch-free. It was then dismantled and transported in 35 truckloads to Falkirk in the summer of 2001, where it was re-assembled.
To cope with the constantly changing immense stresses on the structure during rotation, all steel sections are bolted together, with more than 15,000 bolts connecting 45,000 bolt holes.
Each caisson runs on small wheels fitted into a curved rail fixed on the inner edge of each arm. This ensures that water and boats within a caisson always remain level throughout a rotational cycle. A series of linked cogs provide a back-up in case of any jams.
The cost of the Wheel was £17.5 million. It was opened on May 24, 2002, by Queen Elizabeth II as part of her Golden Jubilee celebrations although, as is the way of the modern world, the opening was delayed a month when vandals forced open the Wheel’s gates.
The Falkirk Wheel is a stunning piece of working sculpture, combining function and design. The arches over the aqueduct add drama. They form a complete circle with their reflection in the canal and generate the feeling of entering a tunnel.
Remarkably, the upper canal ends literally in mid air. Long boat travellers speak of the sense of sailing off the edge into the spectacular Scottish scenery beyond.
For those who want to know more try www.thefalkirkwheel.co.uk. And for those who are thinking of taking a turn during the next tour of the auld sod, a ride on the Wheel last year cost adults £8 and kids £4.