England underwent an extensive Canal Age in the mid Eighteenth Century, lasting for longer than a century. Waterways provided an inexpensive means to move goods across a nation. This, in turn, helping to spark the country’s rapid transformation during the Industrial Revolution. Canals offered remarkable improvements over rutted, muddy overland routes and provided the best transportation alternative in the decades before the invention of railroads.
Bridgewater Canal
Historians frequently cite the 1761 Bridgewater Canal as a blueprint for a network that quickly evolved across the nation. Its builder and owner, Francis Egerton the third Duke of Bridgewater, envisioned a canal as a better way to move coal from his mines at Worsley to nearby towns. Coal from his mines heated homes and fueled industrial expansion.
Nobody had ever tried Egerton’s design in England before. His was the first canal that didn’t following an existing waterway. But he kept his design simple. The canal followed natural topography so it didn’t require locks anywhere along its 65 kilometre (39 mile) path from Leigh to Runcorn; near Liverpool and Manchester. He designed a narrow canal for small slender boats. It served its purpose well enough to inspire numerable imitators.
Manchester Ship Canal
The Manchester Ship Canal, by contrast, was one of the last canals built. It didn’t exist until the 1880’s. This one followed the original paths of the rivers Mersey and Irwell, in a general sense.
Industrialists in Manchester felt that they were at a distinct disadvantage because of the city’s inland location. Oceangoing vessels could not reach the city. On top of that, Manchester businesses paid dearly for railroad access to the docks at Liverpool. So the city lobbied for relief and Parliament approved construction of a canal despite Liverpool’s strong objections.
Construction required an immense effort. This involved extensive dredging, numerous locks, and high overhead bridges to accommodate the passage of large cargo ships. These improvements allowed merchant vessels to sail all the way into Manchester and the city became an important seaport.
Where the Canals Crossed
That was all fascinating of course. Even so, the stories of two specific canals didn’t differ materially from many of the dozens of other English canals. Yet, these two canals crossed physical paths and that’s where things got interesting. Engineers had to find a unique solution to accommodate the situation.
The Bridgewater Canal crossed above the River Irwell on an historic stone arched aqueduct at the town of Barton-on-Irwell. Unfortunately, oceangoing ships on the new Manchester Canal, following the River Irwell, would never fit beneath the aqueduct. So officials had to demolish it. In its place rose a marvelous manifestation of Victorian design, a swing aqueduct.
The Swing
The Barton Swing Aqueduct became the first and possibly the only structure of its type anywhere in the world. It was designed to pivot 90 degrees whenever large ships traveling along the Manchester Canal approached it. This allowed them to pass without obstruction.
Engineers created an artificial island at the center of the canal that served as the pivot point. A control tower built on the island contained the necessary machinery to operate the swing. Some of process involved manual labor as evidenced by the YouTube video. One can see a worker operating a hand crank to move the watergate at the end of the aqueduct. The swing aqueduct is still in operation serving its original purpose, an engineering marvel.
I also appreciated how the feature appeared in online maps. I’d never seen a cartographic representation of a canal crossing above another canal before.
Additional Complexity
In addition there was a road that crossed the Manchester Canal near the same point. It also required a swinging mechanism, called the Barton Road Swing Bridge. The same concrete island and control tower pivoted the road bridge at the same time it pivoted the aqueduct.
Completely Unrelated
Reader “Qadgop the Mercotan” sent an email message to 12MC recently, referencing a conversation on the Straight Dope Message Board under the intriguing title, “Are there any streets with names containing all four cardinal points?” One of the participants on that board, kunilou, discovered a street that met the criteria: Southeast Circle NW in Albuquerque, New Mexico. And it appeared to run into Northeast Circle SW! (map). Many thanks to Qadgop the Mercotan for passing that along.
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