A visit to the Pontcysyllte Aqueduct near Llangollen – Thomas Telford’s iron trough 126ft over the Dee

It is without question a marvel of modern engineering and a remarkable sight, but what strikes most people when they first see the 1000ft (c.305m) Pontcysyllte  canal aqueduct is that the handrail along the pedestrian walkway 127ft (38.5m) over the river Dee is only a few steps away from the other side of the narrow canal trough, which has no handrail at all to separate a boat user from a straight drop into the valley bottom.  Until you lean over the towpath’s handrail and look straight down, 127ft is a rather abstract number.  The photograph on the right shows me crossing it on a 40ft narrowboat in the 1990s on a two week canal holiday.  What you cannot see are the white knuckles with which I am gripping the tiller for dear life, in spite of having absolutely no fear of heights, because there was absolutely nothing between me and that drop.  The aqueduct, Grade I listed, and a UNESCO World Heritage Site since 2009, is the longest and highest in Britain.  It’s a long way down.

The Pontcysyllte Aqueduct passing over the Dee valley at Trevor. Source: Dronepics Wales

Seen from below or from a distance, the Pontcysyllte aqueduct is a fabulous sight, not pretty but truly awe-inspiring, and it shows exactly what Pontcysyllte is:  an iron trough built on 18 vast tapering brick piers, with 19 arches.  It was all about function, nothing to do with aesthetics, and has no ornamentation to soften it, but the sheer ambition of it grips the imagination and makes one look beyond the factual details of the thing.  It really is superb.  There is a path leading down along the side of the approach to the aqueduct into the valley below, a long but well maintained track to the valley bottom, where you can walk along the Dee and get a long at the aqueduct from a distance.  That’s one for another day.

It was a beautiful day, absolutely flawless, with cerulean blue skies, a golden sun warming one’s face, and a brightness of autumnal colours that takes some beating.  After attending the Remembrance Day commemoration at the Churton war memorial, with a memorable and moving address, and a two-minute silence filled with birdsong, I collected the car first, the parent next, and we proceeded towards Trevor, on the A539 to Llangollen.  There’s a brown signpost pointing to the aqueduct’s pay-and-display car park at the Trevor Basin, which is the home of a number of canal boat companies today, but when it was built was used for the transhipment of coal, building stone, iron products, timber and bricks, much of which was brought to the canal wharf by horse-drawn waggons.

Map of the key canal features in the Vale of Llangollen. I have added a red arrow to show the best car park for Pontcysyllte. Click to enlarge. Source: Pontcysyllte Aqueduct & Canal World Heritage Site

Thomas Telford and his chosen team

Portrait of Thomas Telford, who chose to be painted with the Pontcysyllte aqueduct in the background. Engraved by W. Raddon from a painting by S. Lane.

The aqueduct (built (1794-1805) was part of the Ellesmere Canal project.  It is one of the many British civil engineering projects that has the names of Thomas Telford (1757-1834), ironmaster William “Merlin” Hazeldine (1763-1840) and master stonemason John Simpson (1755-1815) attached to it, three men who had brought their particular skills to many different joint projects and in doing so had developed an invaluable relationship of trust and mutual respect.

Thomas Telford started his career as a stone mason, working in London on buildings such as Somerset House, and had ambitions to develop his career as an architect.  When he became the County Surveyor for Shropshire, he worked on a great variety of building projects including, by his own estimation, 40 road bridges between 1790 and 1796, two of which employed iron in their construction.   Hazledine had initially trained as a millwright, but  his family owned a small foundry  and Hazeldine went on to grow his iron casting business with the large Coleham Foundry at Shrewsbury.  Hazledine and Telford, both Freemasons, had met at Salopian Lodge  in Shrewsbury in 1789 and become friends and professional collaborators.  On one of his earliest projects in Shrewsbury Telford hired a childhood friend Matthew Davidson to oversee works, and Davidson employed master stonemason John Simpson who worked on many of Telford’s projects. Telford described Simpson as “a treasure of talents and integrity.”

Although Telford is by far the best known of the three, he, Hazledine and Simpson worked together frequently on many different projects to produce some of the great civil engineering constructions of their era, mainly bridges.  All three were involved with the Pontcysyllte aqueduct, where  Matthew Davidson also joined them, but the story of the canal starts before any of them were recruited to work for the Ellesmere Canal project.

Background to the aqueduct

The Trevor Basin today.

The big name in canal construction was James Brindley (1716-1772), who was responsible for building over 365 miles of canals by the time he died.  Brindely realized that any inland waterway network would need to connect to all the great navigable rivers that connected to the sea, including the Thames, the Mersey, the Severn and the Trent, incorporating other important navigable rivers like the the Avon and the Dee.  Most of his canals were contour canals, wherever possible built on the level and avoiding slopes so that locks and lifts could be avoided.  The network was therefore a sprawling affair, but it revolutionized transport, avoiding roads that would become mired and impassable in winter, as well as unnavigable sections of rivers, and the riverine problems of drought and flood.  Water into and out of the canal system was regulated and therefore predictable, and allowed year-round transport.  The advantages became very clear very quickly, and manufacturing and trading businesses began to locate themselves at critical points on the canal network.  Eagerness to invest in infrastructure resulted in a canal boom in the late 1780s and 1790s.  Each new section of canal required an Act of Parliament, subject to Royal Assent, and Act after Act was passed as the network expanded.

The complex arrangement of the Ellesmere Canal and its branches is shown as a think blue winding line. The thick blue line is the Dee. The yellow lines are roads. Click to see a bigger version. Source: Wikipedia

In 1791 a proposal for a canal to link the Mersey at Netherpool (later renamed Ellesmere Canal) to the river Dee at Chester and the Severn at Shrewsbury was discussed by three Shropshire entrepreneurs, carrying mainly coal, iron and lime, supported by other goods as well.  It was decided that a branch would be needed to Wrexham and Ruabon and onwards, via Chirk, bypassing Oswestry at its west, to Shrewsbury in the south with a branch to Whitchurch in the east and another to Llanymynech.  Originally it was planned to run a branch from Ruabon to reach the Irenant slate quarries near Llantysilio, via Llangollen, but this was at first dropped and later revived for different reasons (discussed below).  That branch would in turn connect to the Montgomery Canal from Frankton Junction via Welshpool to Newtown in mid Wales (for carrying limestone, coal, timber, stone and slates).

This seriously ambitious plan found sufficient support for a surveyor to be hired and possible routes to be explored.   William Jessop, an experienced canal engineer, was hired to head up the project and oversee all of its different components.  After disagreements over the final route were resolved (albeit not to everyone’s satisfaction), the Ellesmere Canal proposal went through parliament and received its Royal Assent in April 1793.  There were still a lot of technical and logistical details to resolve, including how the canal was to cross the Dee and Ceiriog valleys.

It was clear that Jessop needed help, and although the internal promotion of William Turner was Jessop’s first choice, Telford was brought in without his input. It is not certain how Telford, increasingly bored with life as a county surveyor, managed to insert himself into this ambitious engineering project, but the canal was already generating considerable excitement in the area and it looks as though he heard of the position and sought the support of one of Britain’s most prominent industrialists, John Wilkinson, to help him secure it.  Jessop made it clear in his letters what he thought of having Telford, who he had never met, brought in against his wishes as his right hand man, and refused to attend the meeting that appointed Telford to the Ellesmere Canal Company.  In spite of this rocky start, Jessop and Telford seem to have hammered out a decent working relationship, with Jessop teaching Telford what he needed to know about canal construction, and Telford injecting some ideas into the project.  Like Jessop, Telford managed to broker a deal to enable him to carry out other projects when his personal presence was not necessary, and this enabled him to work on other civil engineering works whilst the Ellesmere Canal was being built.

Building the aqueduct

Work began at Netherpool on the Mersey, renamed Ellesmere Port, in 1793.  The 9-mile canal ran down the Wirral to meet the Dee at Chester, and went so well that it opened for traffic in 1795 and was an immediate success.  While this section was underway, discussions were underway about how the canal might cross the Dee.  The original idea presented to the directors by Jessop and Turner, and apparently not opposed by Telford, was a relatively low level stone channel crossing three stone arches, with step locks either side to manage the ascent to and descent from the level of the canal to the aqueduct.   This would have been an expensive option, requiring not only the locks but the management of the water that would feed the locks.  Even after this had been agreed in principle, concerns resulted in a new plan for an iron channel on stone columns.  It is likely that it was proposed by Telford and supported by Jessop partly because it would have reduced the cost as iron was lighter, easier to work and move, and cost less.  A sketch by Telford from March 1794 survives showing an early version of this aqueduct design.

Telford’s Grade 1 listed Longdon-on-Tern aqueduct in Shropshire, 1796. Source: Chris Allen, Wikimedia

In early 1795 Telford had the opportunity to try out a smaller, less ambitious version of the design at Longdon-on-Tern on the new Shrewsbury Canal, on which Telford was also working, as replacement for the incumbent engineer who had died mid-project.  Later in the same year he had built a fully navigable iron aqueduct on a canal that had none of the problems of leakage or shattering that had worried other engineers.  Whether or not this was taken into account by the directors of the Ellesmere Canal Company, they decided in the same year to go for the iron trough on immense stone piers that was eventually built.

Telford’s friend and frequent collaborator, master mason John Simpson soon joined him on the project.  Telford also brought in Matthew Davidson, his childhood friend of Telford, a stone mason, civil engineer and excellent organizer, to oversee the bridge works.  Telford and Davidson had worked successfully together on Telford’s Montford Bridge project of 1790 – 1792.  Shortly afterwards, William Hazledine arrived to establish an ironworks and take charge of the construction work for the iron ribs and the trough.  By assembling three men that he had worked with before and trusted absolutely, Telford was not only ensuring that the project was in good hands, but that he had a team who could operate in his absence. The foundation stone for the aqueduct was laid on 25th July 1795.

Jessop and Telford made wooden models to test the design for the trough, finding that 1000s of iron parts would be needed.  The cast iron for the aqueduct was made of cast iron that was produced in William Hazledine’s new iron foundry nearby at Plas Kynaston, Cefn Mawr.  Hazledine established the Plas Kynaston foundry to service the construction of the Pontcysyllte aqueduct, thereafter taking advantage of the canal network to carry his cast iron in segments to be transhipped by river or sea to where it was needed.  When he built the Eaton Hall Iron Bridge at Aldford on the river Dee (described on an earlier post) it was from Plas Kynaston that the iron was shipped by canal.

After 1801 Jessop was much less involved and Telford also had interests elsewhere, and Telford was also involved in other projects, leaving Davidson, Hazledine and Simpson to run with the project.  The piers rose steadily, each built in turn from south to north by, at the peak of the project, over 500 men.  Jessop had been desperately worried from the beginning by the dangers to workmen’s lives of such tall piers, and safety precautions were taken very seriously, with the loss of only one life.  The iron parts were manufactured as needed at Plas Kynaston, and were numbered according to the order in which they would be needed so that only pieces needed at any one time would be delivered to the site.  First, ribs of iron were fitted to the piers, and then the trough was bolted on top, after which a wooden towpath was fitted to the side.  The entire project was finished in 1805, and opened on a sunny afternoon on November 26th 1805 at a grandiose ceremony followed by a lavish feast.  The entire cost for the aqueduct project was £47,018, which in today’s money translates as around £617,855 (National Archives Currency Convertor).

Metalwork over and under the arch at the left-hand Rhos y Coed bridge.

Although not as visible in the finished design, iron was also used in the Chirk aqueduct on the Llangollen canal where ten semi-circular masonry arches were crossed by a water channel with an iron bed plate and brick sides sealed using hydraulic mortar.  As well as in the aqueducts, iron was used in various ancillary structures too.  for example, Bridge 29, Rhos y Coed, at the Trevor Basin has visible iron metalwork supplementing the stone arch, and iron was used to cap the weir at the Horseshoe Falls.

The role of the aqueduct

Map from Nicholson’s Guide to the Central canal system, showing the stump end (framed in orange) of the planned Ruabon to Chester section of the canal, which was never built and now houses the attractive Trevor boatyard where the visitor centre is located. Source: Nicholson 1989

The Pontcysyllte aqueduct was almost immediately  in danger of becoming something of a white elephant, because its original role as a direct route to Wrexham and Chester was never fulfilled.  The section that led past Trevor Basin over the aqueduct was supposed to run straight on to the west of Ruabon, via Wrexham and on to Chester where it would link with the Wirral stretch leading to the Mersey and to the  Dee and the Shropshire Union Canal.  All that is left of the Trevor-Ruabon-Wrexham-Chester branch is a stump end occupied by the Trevor Basin, where the car park is located.  This is clearly visible on Nicholson’s map left, where the main line of the canal comes to a sudden, abrupt end.

The abandonment of this important part of the original plan was due to both engineering problems and financial issues.  There were only  two obvious engineering options – an enormous tunnel or a series of locks climbing towards Wrexham and another descending into the Cheshire plain where the canal could run along the flat plain to Chester.  The tunnel would have been appallingly costly, and it was difficult to know how the locks, by no means a low-cost option themselves, could have been supplied with the sufficient water.  Although other technologies were considered, they were rejected for reasons of practicality and cost.  This left the problem of where the water was to come from to feed the rest of the Ellesmere Canal and its branches.

Horseshoe Falls

At the far end of the Llangollen canal is Telford’s great arc of a weir, today known as the “Horseshoe Falls,” marking the point at which the Dee begins to feed the Llangollen canal.  An original survey had considered using the water of the Dee as it fell from Snowndonia via Lake  Tegid at Bala and through the Vale of Llangollen as a water source for the canal.  The idea had been to link the canal to a slate works, feeding the canal at the same time.  This proposal was now revisited.  The owner of Lake Tegid gave his permission and the plan was actioned.  At the Horseshoe Falls the canal is fed with water from the Dee via a sluice and meter, and today carries over 11 million gallons of Dee water a day, emptying it into Hurleston reservoir, just north of Nantwich, where the Llangollen Canal meets the Shropshire Union Canal.  I will be posting more about the Horseshoe Falls weir on another day.  There is no turning point for vessels over 10ft long beyond Llangollen, so the final stretch is only used by minimal traffic today.

This means that the vast aqueduct, such a remarkable feat of civil engineering, would only ever lead to the relatively unimportant narrow section of canal and feeder to a complete dead end at Llantisilio after passing high through Llangollen.  This navigable channel is approached from the aqueduct by negotiating a sharp left-hand corner just beyond the exit of the trough.  Although this seems like a sad role for an aqueduct that should have carried many times the traffic that it eventually did, without the aqueduct there would have been no water to feed the rest of the system.

Even without the Ruabon – Chester link, those wishing to carry all their goods by canal were still able to connect to the main canal system, although to reach Chester they had to take a very long way round, and Wrexham was excluded completely.  The Llangollen canal still linked to the Shrophsire Union at its eastern end, from which the rest of the vast canal network could be reached.

  • Chester could still be reached by travelling the full length of the Llangollen canal to Hurleston Junction, just north of Nantwich, on the Shropshire Union Canal.  From here Chester was nearly 16 miles away.
  • Just to the north of Hurleston Junction was the Middlewich Branch, which headed east and linked to the Trent and Mersey Canal, from where Manchester, Stoke on Trent, the eastern Midlands and Yorkshire could all be reached.
  • In the opposite direction, from Hurleston Junction the Shropshire Union ran directly to Birmingham, which was a vast junction for canals in all directions, including London on the Thames and Gloucester on the Severn.

The Cefn Mawr railway viaduct, which opened in 1848.

Along the line that the original canal would have taken, a cast iron tramway was built to connect local collieries and ironworks with the canal, the iron supplied by Hazledine.  This made the Trevor Basin a particularly important hub of activity, taken delivery of bricks, tiles, coal, iron limestone, slate and sandstone for transhipping along the canal.  It was also a boatyard, with  working narrowboats being built and repaired by Hills Boatyard in the dry dock next to the Visitor Centre (now occupied by a floating take-away café).  Later, there was an interchange with the steam railway.

Visiting Pontcysyllte

A small pay-and-display car park is available for visitors at the Trevor Basin, now the home of some canal trip and holiday companies.  There is also a pub with outdoor seating, and a take-away small café on a little boat next to the visitor centre.  There is a lot of disabled parking provided for in the small car park, which is reached from the A539 in Trevor, clearly signposted with brown heritage signposting.   The aqueduct is a very short walk from the car park, and the towpath heads for miles in both directions.

If, before or after crossing the aqueduct, you are interested in finding out more about the general context of the aqueduct and its location in relation to other parts of the canal, at the Trevor Basin there is a visitor centre, a small but nicely put together display space.  As well as a map of the area that takes up a wall and shows all the main features of the landscape and the canal system itself, there is a display of some of the tools that were used in the construction of the aqueduct, which are startlingly basic, and photographs and artists’ impressions of some of the supporting works, including the foundry at Plas Kynaston.  There are ring folders full of additional information, including facts and figures, that you can look through.

Walking the aqueduct itself is not for everyone.  The towpath is rock solid, with a tall handrail on the valley side, but only wide enough for two people, so there is a lot of stopping still to allow others to pass and there is nothing to stop you falling into the canal.  The canal is only just over 6ft (1.8m) wide, and beyond that is an unrestricted (no handrail, no nothing) drop 127ft to the valley floor.  A couple who I passed told me that they were determined to walk the full length and back, but were conquering their fears to do so, and they were gripping firmly to the handrail.

An alternative to walking is to cross by boat.  There are a number of short cruises that leave the Trevor Basin and run for about 20 minutes before turning and coming back (depending on which one you take and the time of year).

For those with uncooperative legs, everything is on the flat, so it is a very good walk for those who find uphill sections of walks difficult.  After rainfall, towpaths always become a bit muddy, and can be slippery, but even though we’ve had some rainfall recently, it was fine.  The towpath between Trevor and Llangollen is beautiful, and a good choice if you can face the aqueduct.

I noticed that one of the passenger boats said that it was suitable for disabled passengers, but I would recommend getting in touch with them first to find out about timings, prices and suitability for different types of disability.

Sources

Books and papers

Glover, J.  2017.  Man Of Iron.  Thomas Telford and the Building of Britain. Bloomsbury

Lynn, P. A. 2019.  World Heritage Canal.  Thomas Telford and the Pontcysyllte Aqueduct.  Whittles Publishing.

Nicholson, R. 1989 (4th edition). Nicholson/Ordnance Survey Guide to the Waterways 2: Central. Robert Nicholson Publications and Ordnance Survey

Rolt, L.T.C. 1958, 2007.  Thomas Telford. The History Press.

Pattison, A.  n.d. William Hazledine (1763-1840): A Pioneering Shropshire Ironmaster.  West Midlands History https://historywm.com/articles/william-hazeldine-1763-1840  (Pattison’s full 278-page M.Phil, on which the article is based, is available here: https://etheses.bham.ac.uk/id/eprint/3358/1/Pattison12MPhil.pdf )

Websites

Canal and River Trust
Montgomery Canal
https://canalrivertrust.org.uk/enjoy-the-waterways/canal-and-river-network/montgomery-canal?gclid=CjwKCAiAp8iMBhAqEiwAJb94z7aIVzLoaYuqtwbDdRQsaUL73ssnmF_u1LpoURZmI9YxVUlrKi15whoCtxoQAvD_BwE

DronePics Wales
Pontcysyllte
https://dronepics.wales/pontcysyllte/

Engineering Timelines
Longdon-on-Tern aqueduct
http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=308

Grace’s Guide to British Industrial History
James Brindley
https://www.gracesguide.co.uk/James_Brindley
William Hazledine
https://www.gracesguide.co.uk/William_Crosley_(1802-1838)
William Jessop
https://www.gracesguide.co.uk/William_Jessop

Pontcysyllte Aqueduct and Canal World Heritage Site
https://www.pontcysyllte-aqueduct.co.uk/

 

 

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