Elegant canal crossings

Yesterday on Facebook, blacksmith Bex Simon (whose work you may have seen on TV shows like Money For Nothing) posted two photos of this wonderful piece of the Macclesfield Canal - the Snake Bridge. It's such a sinuous elegant solution to the problem of horses needing to cross the canal. It means that they could do so without having to be unhitched from the boats they were pulling.

A bit of research led me to similar examples of these bridges - actually known as Roving Bridges. This one has a main road passing over at a higher level.

Innovative solutions like this always excite me - it's the place where art and design come together to produce something practical and beautiful. Another superb example is the Falkirk Wheel in Scotland that links together two canals at very different elevations without the need for hundreds of locks. I've visited the wheel a few times and it never ceases to impress.

And then, of course, there's the Pontcysyllte Aqueduct (pronounced Pont–ker–sulth–tay) that crosses the River Dee in the Vale of Llangollen in northeast Wales. The 18-arched stone and cast iron structure was completed in 1805 having taken ten years to design and build. It is 12ft (3.7m) wide and 1008ft (307m) long, making it the longest aqueduct in Great Britain. And, at 126ft (38m) high, it's also the tallest canal aqueduct in the world. A footpath runs alongside the watercourse on one side.

The aqueduct was designed by civil engineers Thomas Telford and William Jessop and consists of a cast iron trough supported on iron arched ribs carried on eighteen hollow stone piers (pillars). Each of the 18 spans is 53ft (16m) wide. 

An extraordinary feat of engineering for the technology of two centuries ago.