The 35-m-high, 1,500-tonne structure, internationally recognized as an engineering marvel, reconnects the Forth & Clyde Canal and the Union Canal, a vertical drop of 18 m, and provides water transport between Edinburgh and Glasgow. Conceived in the 1990s as part of the United Kingdom's Millennium Project, its owners, British Waterways Scotland, were seeking a novel, landmark design to take an Industrial Revolution-era project into the new century. The two canals had been connected through a series of 11 locks that were taken out of service in the 1930s when overland transport by road and rail supplanted the canal system. The canals were closed altogether in the 1960s. The Falkirk Wheel, a rotating lift operating through what BWS Business Development Manager Richard Millar calls a "simple and elegant design," move two gondolas on opposite arms from one level to the other. Each gondola, or caisson, contains at least 250,000 L of water and can carry up to eight boats at a time.
The Millennium Link project sought to restore navigability through central Scotland, but needed to connect the historic Forth and Clyde canals, separated by some 35 meters, in order to do so. Rather than looking for a terraforming, futuristic solution, the Falkirk Wheel’s architects and engineers came up with a perfectly old-fashioned mechanical solution: a rotating boatlift.
Unique in the world, the Falkirk Wheel is in a sense quite simple. One boat enters the bottom lift while another (which has traveled on an elevated water bridge from the other canal) enters the top lift. When they are both secure, the wheel turns and the two boats are exchanged, with the one that was on the bottom now zooming off on the elevated waterway.
The Falkirk Wheel functions based on the Archimedes theory of displacement, which states that a floating object (in this case a boat) displaces its precise weight in water. Combining this ancient principle with its perfectly balanced modern design means that a full, seven-minute rotation requires less energy than powering 100 light bulbs!
But what about those spikes? Engineers have been known to come to blows during booze-fueled debates on the matter. In reality, the horns neither compensate for mechanical torque or play in the gears, nor do they break water tension to provide a smooth entry into the bottom canal. Instead, they’re a purely aesthetic nod to the traditional Celtic double-headed spear, while also serving as a metaphor for how the Wheel helps to connect the ‘backbone’ of Scotland’s waterways.