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Pontcysyllte Aqueduct Designed By Civil Engineers Thomas Telford & William Jessop, Ellesmere Canal (Not Completed) - Llangollen Canal, Shropshire Union Canals, Wales.

The Pontcysyllte Aqueduct (Welsh pronunciation: [ˌpɔntkəˈsəɬtɛ]; Welsh: Traphont Ddŵr Pontcysyllte) is a navigable aqueduct that carries the Llangollen Canal across the River Dee in the Vale of Llangollen in northeast Wales.

 

The 18-arched stone and cast iron structure is for use by narrowboats and was completed in 1805 having taken ten years to design and build. It is 12 feet (3.7 metres) wide and is the longest aqueduct in Great Britain as well as the highest canal aqueduct in the world. A towpath runs alongside the watercourse on one side.

 

The aqueduct was to have been a key part of the central section of the proposed Ellesmere Canal, an industrial waterway that would have created a commercial link between the River Severn at Shrewsbury and the Port of Liverpool on the River Mersey. Although a less expensive construction course was surveyed further to the east, the westerly high-ground route across the Vale of Llangollen was preferred because it would have taken the canal through the mineral-rich coalfields of North East Wales. Only parts of the canal route were completed because the expected revenues required to complete the entire project were never generated. Most major work ceased after the completion of the Pontcysyllte Aqueduct in 1805.

 

The structure is a Grade I listed building and part of a UNESCO World Heritage Site.

 

The aqueduct was designed by civil engineers Thomas Telford and William Jessop for a location near an 18th-century road crossing, Pont Cysyllte. After the westerly high-ground route was approved, the original plan was to create a series of locks down both sides of the valley to an embankment that would carry the Ellesmere Canal over the River Dee. After Telford was hired the plan was changed to an aqueduct that would create an uninterrupted waterway straight across the valley. Despite considerable public scepticism, Telford was confident his construction method would work because he had previously built a cast-iron trough aqueduct – the Longdon-on-Tern Aqueduct on the Shrewsbury Canal.

 

The aqueduct was one of the first major feats of civil engineering undertaken by Telford, who was becoming one of Britain's leading industrial civil engineers; although his work was supervised by Jessop, the more experienced canal engineer. Ironwork was supplied by William Hazledine from his foundries at Shrewsbury and nearby Cefn Mawr. The work, which took around ten years from design to construction, cost around of £47,000. Adjusted for inflation this is equivalent to no more than £4,820,000 in 2023, but represented a major investment against the contemporary GDP of some £400 million.

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Uploaded on June 21, 2023
Taken on September 18, 2023