Pontcysyllte Aqueduct

Details

Hits: 891

The Pontcysyllte Aqueduct carries the Llangollen Canal over the valley of the River Dee, between the villages of Trevor and Froncysyllte, east of Llangollen in north Wales.

It was completed in 1805, and it is the longest and the highest aqueduct in Britain, and is a Grade I Listed Building.

It was built by Thomas Telford and William Jessop, it is 1,007 feet long, 11 feet wide and 5 feet 3 inches deep. It consists of a cast iron trough supported 126 feet above the river by 19 hollow masonry piers. Each span is 53 feet wide.

 It was thought by many that his idea would not work, but Telford was confident as he had built at least one previous cast iron trough aqueduct at Longdon-on-Tern on the Shrewsbury Canal.

The mortar he used was made of lime, water and ox blood.

The iron castings were produced at the Plaskynaston Foundry, and each casting dovetails into the next. Telford used Welsh flannel dipped in boiling sugar to caulk the joints, then they were sealed with lead. This was then left for six months with water inside to make sure it was watertight.

It took ten years to build and was opened on 26 November 1805, at a total cost of £47,000.

The towpath is cantilevered over the trough, which is the full width of the aqueduct, so that narrowboats are able to move more freely through the water.

Walkers are protected by railings on the outside edge of the towpath. As the edge of the trough is only about 6 inches above the water level, and therefore below the deck of a narrowboat, the boat steerer has nothing between them and the sheer drop to the valley below, a truly remarkable experience, which sends many feint hearted passengers safely in doors.