Pontcysyllte Aqueduct and Canal

Official name: Pontcysyllte Aqueduct and Canal

Location: Wrexham, Wales

Type: Cultural

Year of inscription: 2009

Pontcysyllte Aqueduct and Canal is the highest canal aqueduct in the world and the longest in the United Kingdom, making it a civil engineering masterpiece and an area landmark. This raised arched stone and cast-iron structure make it possible for the Llangollen Canal to cross over the top of the river Dee in northeast Wales and flow to neighboring England. It is navigable by narrowboats and has a towpath above the waterway that allows for displaced water to flow under the towpath and around canal boats. A footpath runs alongside it that used to be for horses to tow the boats across the aqueduct, but is now exclusively for pedestrians to walk along the river. The trough that runs alongside the aqueduct is only six inches above the canal waterline, which gives the impression of the boats having no protection from veering off the aqueduct. This makes a journey across the canal via narrowboat an exciting tourist experience.

Pontcysyllte Aqueduct and Canal were named a United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage Site in 2009 to preserve the cultural significance of the site. In addition, it is also considered a Grade 1 listed building in the United Kingdom, meaning that it is a structure of “exceptional interest.” It is valued not only for its engineering and historical significance, but also its commanding presence in the countryside.

The structure of the aqueduct is 1,008 feet (307 meters) and 12 feet (3.7 meters) wide, and stands 126 feet (38 meters) tall. It has eighteen 53-foot-wide (16-meter-wide) arched and ribbed spans that are supported by hollow stone pillars anchoring it in the riverbed below. The mortar holding the stone masonry together is made of lime mixed with water and ox blood to provide strength during freeze-thaw temperature cycles.

The site is located in Froncysylite, Wrexham, Wales. The Welsh community in Wrexham County Borough village can be found just off the main A5 highway. The name of the aqueduct is a Welsh word that means “the bridge that connects Cycsyllte”, and “Cycsyllte” was a district of the parish of Llangollen that is at the southern end of the aqueduct. The aqueduct originally served as a waterway bridge to connect villages in the Llangollen parish by canal and transport people and goods.

History

The Pontcysyllte aqueduct was designed by British civil engineer Thomas Telford, who had experience with other canal projects, and built by the Ellesmere and Chester Canal Company. The original plan was to use a series of locks so the canal could cross the River Dee, but Telford engineered the aqueduct to carry what was then known as the Ellesmere canal above the river. His plan was similar to the trough-style cast- and wrought-iron aqueduct system he designed for the Shrewsbury canal to use the Longdon-on-Tern aqueduct. He worked under civil engineer William Jessop, who had more extensive canal engineering experience. Iron for the supports and the trough was provided by the Ironmaster and millwright William Hazeldine, who had a foundry in the major market town of Shrewsbury, and the Plas Kynaston Foundry in the nearby village of Cefn Mawr.

Work began with the design in the 1790s, and the first stone was laid on July 25, 1795. The total cost of the project was £47,000 ($56,500), which was a considerable amount of money at the time. Landowner Richard Myddleton of Chrik was a patron of the canal project and helped to fund it. It took about ten years to finish the project, and the aqueduct finally opened to canal and pedestrian traffic on November 26, 1805.

The original plan was for the canal to continue on to Moss Valley where there was a reservoir built by Telford to provide enough feeder water for the canal to span between the nearby Trevor Basin in Wrexham, Wales, and the city of Chester in England. However, this plan was abandoned. All that remains of the feeder channel can be found in the Wales village of Gwersyllt, and a street named Heol Camlas, meaning “Canal Way” in Welsh. Because of this change in plans, the canal ends in Trevor Basin just north of the aqueduct, and a feeder channel built in 1808 supplies water from the River Dee. Telford also built a low dam on the River Dee called a weir to help maintain the water level, and this is known as Horseshoe Falls.

In 1846, the Pontcysyllte aqueduct and canal were merged into the Shropshire Union Railways and Canal Company in the hopes of using the existing canal route to craft a more efficient railway route. However, in 1849, the plan to turn the canal route completely into a railway was canceled, and the canal remained open. Later, the Pontcysyllte aqueduct became a part of the Shropshire Union and served the war effort in World War I (1914–1918) by supplying a fleet of hundreds of narrowboats.

In 1936, a major waterway breach near Newton, Powys, occurred and drastically reduced commercial traffic on the canal. By 1939, most narrowboat crossings had been discontinued, and the London Midland and Scottish Railway Company Act of 1944 officially closed the canal to navigation and commercial traffic. Because of this closure, there was a lack of routine maintenance which resulted in a serious canal breach near Sun Bank Halt east of Llangollen in 1945. A 50-foot (15-meter) deep by 120-foot (37-meter) wide section of the embankment washed away, causing a mail train to derail, killing one crew member and injuring two others.

Although no longer in use for commercial waterway traffic, the aqueduct had to remain active to serve as a feeder for the Shropshire Union canal and to supply drinking water to the reservoir in Hurleston. As a result, in 1955, the Mid & Southeast Cheshire Water Board agreed to maintain the canal and its operations. By the second half of the twentieth century, however, tourist and leisure boating on canals increasingly became popular. In the 1980s, the canal was renamed the Llangollen Canal and rebranded from an industrial canal into a sightseeing landmark. The Canal & River Trust, or Glandŵr Cymru in Welsh, maintains and manages the canal for tourist use, keeping in in good repair.

Significance

Pontcysyllte Aqueduct & Canal World Heritage Site provides its locale with 11 miles (18 kilometers) of waterway that spans not only the famous Pontcysyllte Aqueduct, but other smaller historical aqueducts, tunnels, viaducts, embankments, and a railway line to connect Wales and England along the length of the canal that encounters varying terrain. It is a masterpiece of late eighteenth century and early nineteenth century civil and industrial engineering, making it a landmark of cultural significance. The UK has designated the site a Scheduled Ancient Monument of National Importance, and an Area of Outstanding Natural Beauty, which allows it protection.

Pontcysyllte Aqueduct & Canal was declared a UNESCO World Heritage Site to preserve its innovative creativity of canal engineering. UNESCO World Heritage Sites must meet at least one of ten established selection criteria. It meets three criteria, I, II, and IV. Criterion I must “represent a masterpiece of human creative genius,” and the pioneering structure of the aqueduct using cast- and wrought-iron arches supported by stone piers is considered a great masterpiece of Telford and provided a foundation for his international civil engineering reputation.

Criterion II states that a site must “exhibit an important interchange of human values, over a span of time or within a cultural area of the world, on developments in architecture or technology, monumental arts, town-planning or landscape design.” The architecture of the canal and the aqueduct successfully dealt with a challenging geographical region that posed many difficulties to planners and engineers. However, these technical difficulties were overcome, and the design of the artificial waterway contributed greatly to the progress of the canal engineering field following its construction.

To meet criterion IV, a site must “be an outstanding example of a type of building, architectural or technological ensemble or landscape which illustrates (a) significant stage(s) in human history.” The canal and associated structures, including the impressive Pontcysyllte Aqueduct, played a crucial role in the Industrial Revolution to support the burgeoning technology of the early eighteenth century. It supported transportation not only along its commercial waterways but through rail lines that later followed the canal pathways.

The integrity of the canal waterway and associated structures is maintained by keeping its original form, although stabilization and waterproofing by British Waterways and the Canal & River Trust have been done to maintain safety and working order to continue operations. This has presented some technical challenges, but the waterway has maintained its overall historical characteristics while providing a recreational opportunity to the region. This contributes to the historic and cultural value of the site as an example of canal waterway transport during the Industrial Revolution in the United Kingdom.

Bibliography

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“Pontcysyllte Aqueduct and Canal.” UNESCO World Heritage Convention, 2022, whc.unesco.org/en/list/1303/. Accessed 26 July 2022.

“Pontcysyllte Aqueduct and Canal World Heritage Site.” Cadw, 2022, cadw.gov.wales/advice-support/historic-assets/other-historic-assets/world-heritage-sites/pontcysyllte-aqueduct-and. Accessed 26 July 2022.

“Pontcysyllte Aqueduct & Canal World Heritage Site.” Pontcysyllte Aqueduct & Canal World Heritage Site, 2020, www.pontcysyllte-aqueduct.co.uk. Accessed 26 July 2022.

“Pontcysyllte Aqueduct World Heritage Site.” Canal & River Trust, n.d., canalrivertrust.org.uk/places-to-visit/pontcysyllte-aqueduct-world-heritage-site. Accessed 26 July 2022.

“Pontcysyllte Aqueduct & Llangollen Canal.” Britain Visitor, 2022, www.britain-visitor.com/britain-travel-guide/pontcysyllte-aqueduct. Accessed 26 July 2022.

“The Criteria for Selection.” UNESCO World Heritage Convention, 2022, whc.unesco.org/en/criteria/. Accessed 26 July 2022.