MSSA

AMAZING STEEL: THE FALKIRK WHEEL

There is a must-see amazing steel structure in Falkirk which is touted as the worlds' only rotating boat lift. Before the railways came to Scotland, there were two main canals which connected major towns to the local coalfields. The Forth & Clyde canal was the first, with work starting in 1768. Eventually the canal connected to the River Clyde with a branch cut down to Glasgow. The full 56 km canal with 39 locks and 32 swing bridges began operation in 1790. It was wide and deep enough that sea going barges could navigate from the West side of Scotland to the East side and vice versa, bringing prosperity to the region and allowing manufacturers to move their good to the European markets. Indeed, the design for the famous "puffer" steam-powered boats was developed on this canal, thus allowing a passenger service to be started.

Starting in Edinburgh, the Union canal was cut through to Falkirk and the Forth & Clyde canal, opening in 1822. As a semi-contour canal, there are no locks along its 51 km route as it follows the 73 metre (240 ft) contour across the land. However, to maintain that level many impressive aqueducts, tunnels and bridges had to be built which are marvels in themselves.

The original link between the two canals at Falkirk was via a series of 11 locks to allow boats to rise or fall the 35 meters between the two water levels. Anyone who has had a holiday on a canal boat will tell of the toil necessary in navigating down through a canal lock. First the back gates are opened and the boat guided in. Then the back gates are shut and the sluices opened in the front gates to let the water rush out to the lower level. When the water levels have evened out, the sluices are shut and the front gates are opened so that the boat can continue its journey. Going up is the reverse process. When busy, there is a queue and the boat has to wait its turn. This takes time, energy and patience. Whilst the modern canal user may be doing this for fun, in the 1800's the canals were used by dour Scottish bargemen who did not think much of the 1 day that it took to get a boat through the 11 locks from one canal to the other.

Once railways came to the area, both canals began to decline. In 1933 the 11 locks linking the two canals were filled in and built over. In 1970, the M8 motorway was simply built across the Union, thus blocking the canal. The Forth & Clyde canal suffered the same fate of disuse and decline.
Rescue came in the form of a huge £84.5 million Millennium restoration project to clear all the obstacles blocking both canals and reopen in 2001 for pleasure cruises which have become a very popular pastime. The towpaths are available for walking and cycling and the whole area has become refurbished and revitalised, creating jobs and tourism. However, rebuilding the 11 locks at Falkirk was not an option, hence the need for an innovative boat lift.

Many designs were presented, but the design finally chosen uses two gondolas which counterbalance each other. They individually weigh 300 Tonnes when filled with 500,000 litres of water, and a clever aspect of the design exploits Archimedes' Principle in that a body displaces its own weight in water, so when up to eight boats are guided into a gondola, the gondola still weighs the same as it did without any boats. One gondola is at the bottom of a huge arm and is open to the Forth & Clyde canal. The other gondola is held vertically above and is connected via an aqueduct and tunnel to a new stretch of the Union canal especially built for the purpose. The whole structure holding the two counterbalanced gondolas then rotates on a 3.5 metre axle using only 1.5 KWh of electricity to turn the 600 Tonne weight through 180° in 5½ minutes. Another clever aspect uses a set of 8 m diameter cog wheels to make sure the gondolas stay level as the wheel rotates.

The structure uses 1,200 Tonnes of steel bolted together with a 10mm tolerance using 15,000 bolts into 45,000 holes rather than welds as it was felt that welds would not be able to withstand the ever changing stresses that build up as the structure turns. It took 35 lorry loads to carry the parts to the work site from Butterley Engineering Works in Derbyshire. The wheel was opened to the public by Queen Elizabeth in May 2002.

What used to take a day to navigate 11 locks can now be completed a few minutes thanks to this engineering marvel in steel!