Welsh Bridges: 23. Dernol Footbridge, River Wye

This was the third of three bridges that I tried to visit on the River Wye in Powys in August this year.

The first was barely a ghost, and the second a literal washout. Would it be third time lucky?

I parked up in a layby on the A470, north-east of the bridge, and followed a public right of way through the fields and downhill towards the site of the bridge.

A bridge! A palpable bridge!

Alan Crow's book Bridges on the River Wye indicates that a suspension footbridge was built here in 1975 by the Newbridge-on-Wye firm N.R. Hope. From the description, it is the same bridge that can be seen today, except that all or much of the fabric may have been renewed. Powys County Council tell me that the bridge was "refurbished" in 2018.

The bridge is of essentially the same design as the now-destroyed Cwmcoch footbridge, constructed by the same builder in 1967.

Timber towers sit on concrete footings, and support a steel tube or roller over which the main cables pass. Additional stay cables are attached to the rear face of the towers.

The main cables are anchored to steel cantilever beams at each end of the bridge. Three parapet wires on each side of the bridge are also tensioned against these cantilevers, and the tower stay cables are spliced into the lower of these parapet wires.

The bridge floor comprises three timber planks running longitudinally, sitting on transverse timber members. Every third cross-member also provides the support for braced parapet posts.

Below the bridge decking, six parallel wires run longitudinally, and these provide substantial support to the deck along most of its length, as there are no vertical hangers as you would expect on a conventional suspension bridge. The deck wires are anchored to steel cross-members attached to the main anchor stanchions.

The main suspension cables only directly support the middle part of the deck. The two cables pass below grooved longitudinal timber members on each edge of the bridge.

In the absence of the under-deck wires, this would be quite an unstable arrangement, as the central portion would "rock" longitudinally under load. The deck wires are therefore essential both to prevent that rocking, and to support the deck between the points where the main cables connect.

I've included a few more photographs to illustrate both the details and the setting of this attractive, economical bridge, and a video to show how much it moves under a single person load.

Further information:

• Google maps
• Bridges on the River Wye, Alan Crow, 1995

"Bill Brown's Bridges" by David Boxall

I've remarked in the past how few books there are on the great bridge designers of the 20th century, other than one or two of the earliest decades such as Robert Maillart and Othmar Ammann. Even many bridge design professionals will struggle to name designers comparable with the likes of the nineteenth century's Telford, Stephenson and Brunel.

In the 20th century, the increase in scientific understanding of structural design and consequent specialisation made large projects more and more the province of a broad team rather than a singular man and his support office. This was especially the case where the scale or sensitivity of projects required decision-making to be collective rather than dictatorial.

Of course, it was always the case that the big names were often just those who fronted up the work of a broader team. That's nothing new, although it does sometimes seem as if in the late 20th and early 21st century the only entities that can be credited for a bridge design are the engineering corporation or the architect. Individual engineers, not so much.

With all that in mind, I was keen to read "Bill Brown's Bridges" by David Boxall (301 Publishing, 2015, 148pp, available from b2.co.uk), a biography of one of Britain's most successful suspension bridge engineers, who worked on the Forth Road Bridge, Severn Bridge, Erskine Bridge, Humber Bridge, two bridges over the Bosphorus straits, and on unbuilt proposals for the Messina Strait Bridge. Brown has been credited with the aerodynamic box girder design for the Severn Bridge, which radically changed the economy and feasibility of major suspension bridges.

Boxall runs a marketing and design agency, but was previously manager of Brown Beech Associates. This book is very much an "official biography", produced with the cooperation of Brown's wife Celia, and its aim is to document and cement the legacy of one of Britain's most successful bridge engineers.

Born in south Wales in 1928, Brown studied engineering at Southampton and then completed a PhD at Imperial College. His family background was technical in that his grandfather and father were both cabinetmakers. On graduating from Imperial in 1951, Brown was fortunate to go straight into employment with the engineer Gilbert Roberts at Freeman Fox.

Roberts was one of the top engineers of the day, responsible for the structural design of the Dome of Discovery for the Festival of Britain. He had worked with Sir Ralph Freeman on the design of the Sydney Harbour Bridge (1932), and on a suspension bridge on the Zambia - Zimbabwe border (1939).

Over the course of eighteen years until Roberts retired in 1969, Brown was exposed to progressively more challenging engineering and greater levels of responsibility. By the time he became a partner in the Freeman Fox firm in 1970, he had worked on some truly exceptional projects.

His early years included work on major cranes, and a major steel arch structure, Adomi Bridge in the Ghana (1957). Developments in welding and higher-strength structural steels during the 1950s were to prove essential for what would follow in the 1960s.

Freeman Fox's design team, led by Gilbert Roberts, were appointed (alongside Mott, Hay and Anderson) to develop designs for both the Forth Road Bridge (1964) and Severn Bridge (1966). These were spans well in excess of the largest suspension bridge recently built in the UK (Tamar Bridge, 1961). It had been two decades since the collapse of the ill-fated Tacoma Narrows bridge, but aerodynamic concerns remained high in engineers' minds.

Both the Severn and Forth bridges were initially designed to be built using the truss decks then seen as the norm. Fortuitously, an accident in wind tunnel testing during design of the Severn bridge led to a model being mostly destroyed. The book recounts that for the replacement model Brown sketched out a very different slender box-girder geometry, that could be built quickly out of plywood and used for the remaining testing. Severn went on to become the first large suspension bridge built using an aerodynamically stable box girder, a major innovation.

What the book doesn't say is that the slender box-girder concept was not new to the Severn crossing: German engineer Fritz Leonhardt had proposed the same idea for the Tagus suspension bridge in 1960, albeit with two separated box girders rather than just one. Indeed, much of the development of welding and stiffened steel plates for bridge construction had been undertaken in Germany.

The book goes big on Brown's role here (and elsewhere) as an innovator, but says nothing about the Severn Bridge's legacy of problems: fatigue in the inclined suspension hangers, issues with the quality of welded plate, and the need for expensive strengthening. Innovation is never without risk, and on this scale, the consequences can be significant.

Box girders were also used by Freeman Fox for the nearby Wye Bridge, the Erskine Bridge, and for the West Gate Bridge in Melbourne, Australia. The latter collapsed, killing 35 people, in October 1970, and Brown was amongst the senior Freeman Fox staff summoned to testify at the subsequent inquiry in Australia. Boxall records partner Dr Oleg Kerensky's view that the collapse was the fault of the contractors, and that the design had been sound. This is misleading: Freeman Fox's design calculations and site supervision were condemned as completely inadequate by the inquiry.

At the time the West Gate Bridge collapsed, Freeman Fox had already been working on plans for a new suspension bridge across the Bosphorus for three years. This adopted both the aerofoil deck from the Severn Bridge, and also the triangulated layout for the suspension hangers, an idea which had seen little if any use elsewhere.

Completed in 1973, the first Bosphorus Bridge was the longest span outside the USA at the time it was built, and is quite possibly Roberts and Brown's finest achievement. Freeman Fox took on significant overall responsibility for guiding and supervising the project, not just its design, and Brown relocated to Istanbul for most of the construction phase.

By the time of the even longer Second Bosphorus Bridge (1988), Brown had left Freeman Fox and set up his own firm, Brown Beech Associates (in a huff, to paraphrase the book's account). His role this time was as the client's technical advisor, rather than as designer. This bridge adopted conventional vertical hangers, unlike the triangulated ones used on Severn and the previous Bosphorus span, and a few years later the latter bridge had its hangers replaced with vertical cables as well.

In his later years, Brown worked as a consultant on a number of structures, including the Messina Strait Bridge and the Storebaelt East Bridge, both developing concept design proposals and advising on more specific issues such as cable-spinning techniques. He passed away aged 76, in 2005. The book includes a gallery of images of nine key structures that he worked on, and they truly are an incredible CV.

I think it's fair to say that this official biography is a partial account - broader and more balanced accounts of the development of twentieth century suspension bridges are available elsewhere. However, the book is well written, well illustrated and well presented. There are dozens of great photographs of some truly epic bridges, and it's great to see a twentieth-century British bridge engineer recognised in this way.

There was a period from the completion of the Severn Bridge to the completion of the Humber Bridge when it appeared that Britain had firmly re-established itself in the vanguard of long-span bridge design, and as part of the Freeman Fox team Bill Brown was clearly central to that.

Welsh Bridges: 20. Llantysilio Chain Bridge

This bridges goes by a number of names - Berwyn Chain Bridge may be equally as appropriate. Signs at the site just call it "The Chain Bridge". It is neither a Listed Building nor a Scheduled Monument, which will only be surprising if you incorrectly imagine that our heritage bodies are competent.

The first bridge across the River Dee at this location was the work of local man Exuperius Pickering, variously described as an entrepreneur or a "coalmaster". Pickering was looking for a way to transport his coal and other materials between the Llangollen Canal (1808) and Telford's recently improved London to Holyhead Road, without paying tolls to cross Llangollen Bridge. Conceived in 1814, his bridge was completed in 1818.

This was a period of rapid development in cable or chain-supported bridges within the United Kingdom. Granted, the Winch Bridge, an iron chain catenary structure, had been built over the River Tees in 1741. However, it was the early 19th century when cable and chain bridges took off, with stayed bridges in Galashiels (1816), King's Meadow Bridge (1817) and Dryburgh Abbey Bridge (1817, rebuilt as a suspension bridge in 1818), and the Union Chain Bridge (1820, suspension bridge). Things advanced rapidly enough for Robert Stevenson to present an article surveying these and other designs in 1821, as well as proposing his own bridge at Cramond, an underspanned suspension bridge, which was never built.

Pickering's bridge sits right in the middle of this chronology. Happily for posterity, drawings of the bridge were made by the French traveller Joseph-Michel Dutens (see below). These show the bridge to be an underspanned suspension bridge, with eyebar chains supporting the deck, and an additional tension rod below this, perhaps to enhance stability. The bridges I mentioned above were well-reported, and it's often stated that Stevenson was the first to propose an underspanned suspension bridge, and James Smith's Micklewood Bridge (1831) the first to be built. In reality, Pickering got there first, although how much of an improvement his structure was over a simple catenary bridge might be doubtful.

The first drawing by Dutens shows half of the bridge (it was a three-span structure), while the second drawing gives cross-sections and details of the chains. A dozen chains passed below the bridge deck to provide support.

In addition to the drawings, photographs of Pickering's bridge survive, although showing it enhanced on one side by a timber truss.

The bridge lasted remarkably well, until it became unsafe and was dismantled in 1870. In 1876, Henry Robertson, owner of Brymbo Ironworks, rebuilt the three spans and re-used the original chains, again adopting the underspanned system (photograph below). This one was destroyed in flooding in 1928.

Roberton's son rebuilt the bridge the following year, but this time with only a single pier in the river. The chains were re-used, but now to form a suspension bridge, with three suspension chains on each edge, and two stiffening chains connected along the deck underneath.

One tower sits on an outcrop of rock within the river, and the other on the river wall at the north edge. The river tower was protected by a large concrete pier, rendering the new bridge far less susceptible to flood damage.

The chains at the south end of the bridge were anchored into the ground, while at the north end they pass over the adjacent Chainbridge Hotel and were anchored into rock high above the canal. The deck chains were anchored into the ground using an adjustable tensioning system.

A pair of bars hang downwards from each chain link, and these are connected to a triangulated system of lower hangers. These in turn carry the lower deck chains and the timber deck.

The bridge was load-tested with 45 people when it opened, and lasted reasonably well, becoming gradually more dilapidated until being closed as unsafe in 1984. In 2014-15, it was completely refurbished, with all the metalwork carefully dismantled and then reinstated.

The works were completed by local firm Shemec Ltd to a design by consultants Ramboll. The engineers completed a careful structural assessment of the bridge, determining that even if corroded ironwork was replaced, it could not carry anywhere near modern loading requirements, being limited to 1.5 kPa of load. This equates to roughly 5 tonnes of load on the 24m main span, or around 60 people. Llangollen Town Council, who had taken over responsibility for the bridge, agreed that this was sufficient. Warning signs at the end of the bridge request that no more than ten people use it at once.

The reconstruction works are well documented in a paper by Ramboll and in photos on the Chain Bridge Project website. I'm not clear what proportion of the original metalwork was preserved and reused, but new pieces were fabricated in mild steel to match the existing details and dimensions wherever any piece could not be reused. All the chain pins had to be replaced. Nonetheless, in the rebuilt bridge it is claimed that these are the oldest bridge suspension chains in Britain to remain in use.

Prior to the refurbishment, there was no parapet remaining on the bridge. The reconstruction introduced a series of new parapet posts, a tensioned upper cable, and a mesh infill system. I'm not sure how well these match any parapet that had been there in the past, but I doubt the new system is compliant with normal modern standards.

Indeed it's interesting to compare the refurbishment work at Llantysilio with what was done at Brabyns Park Bridge in Marple, which I discussed in a recent post. The chain bridge project is an exemplary piece of conservation engineering, where even though the structure is not Listed, it has been treated with integrity and the original details preserved as closely as possible. The engineers sensibly recognised that compliance with modern standards would have been entirely inappropriate. By contrast, the Marple structure is Listed Grade II, but senseless attempts to impose modern standards on it have largely ruined its appearance (although thankfully not irreversibly).

The Llantysilio Chain Bridge is unique both in the complex history of its surviving structural fabric, and in its form and details. It is well worth visiting, in a setting within view of two other fine bridges, and with plenty more to see within walking distance.

Further information:

• Google maps
• Wikipedia
• Engineering Timelines
• Structurae
• Grace's Guide
• Coflein
• People's Collection Wales
• Chain Bridge Project
• The Chain Bridge Documentary (video)
• Plas Kynaston Canal Group
• The Refurbishment of Llangollen Chainbridge (Marginson / Matthews, Footbridge 2017)

Welsh Bridges: 17. Menai Suspension Bridge

Where do you start when trying to write a simple blog post about a bridge like this? So much has already been written (see links at the end, which are selective and do ignore some of the more detailed publications)!

The first serious proposal for a bridge over the Menai Strait came in 1802, when John Rennie proposed a multi-span viaduct of masonry and cast iron. A few years later, in 1811, it was Thomas Telford's turn, presenting designs for either a multi-span cast iron viaduct similar to Rennie's or for a single cast-iron span. Neither of these ideas were adopted.

Telford revisited the site in 1818, and prepared plans for a suspension bridge instead. Construction work began on 10th August 1819, three years ahead of Telford's suspension bridge at Conwy. Both bridges were completed in the same year, 1826.

The bridge at Menai became the longest bridge span in the world, its 577 feet length exceeding the 449 feet of Samuel Brown's Union Chain Bridge, completed six years earlier in 1820. Brown's bridge had commenced construction only a few days before the Menai bridge, on 2nd August 1819, but was built much more quickly than Telford's bridge.

Menai Suspension Bridge held the span record for 8 years before being overtaken by the 889ft Fribourg Suspension Bridge, in  October 1834, a month after Telford's death. It's maybe worth noting as a historical aside that the Union Chain Bridge's earlier record is attached to some degree of doubt: the 1430 Chushul Chakzam footbridge in Tibet may have been a very similar span, although records are poor.

The Menai Bridge's span was a remarkable achievement, and if it isn't Telford's finest bridge, I think it's the most substantial engineering challenge that he ever took on.

Telford had been looking at suspension bridge ideas since 1814, when he was commissioned to develop a proposal for a road bridge at Runcorn. That design was for what would have been an astonishing 1000ft span, something that would not be achieved on any bridge until 1849. Telford proposed to form the Runcorn bridge's catenaries out of half-inch square iron bars, welded and bound together into sixteen "cables" each comprising 36 such bars. He arranged for extensive testing of the strength of iron to inform the design, and built a model suspension bridge 50ft long.

The promoters of the Runcorn crossing invited others to submit designs for review by Telford. The only submission to meet his approval was a suspension bridge proposal from Samuel Brown, who proposed catenaries comprising iron chains. Telford visited Brown's factory in February 1817, where he was driven across Brown's own model bridge, albeit quite a substantial model some 100ft in span. At the time, Brown was working with chains made from iron rods, as he was to use for the Union Chain Bridge, although he also developed chains made from flat iron plate.

The Runcorn bridge was never built, but when invited to develop the Menai crossing, Telford at first continued with his idea of square iron bars welded and bundled to form cables. Perhaps he was influenced by Brown's patenting his own chain bridge ideas in mid-1817. It was only later, as work proceeded on the masonry parts of the Menai bridge that Telford switched to flat-bar chains, supplied by William Hazledine. There were to be sixteen chains in total, with four groups of four chains arranged vertically above each other; one group at each edge of the bridge, and two on the centreline of the roadway. There is a good image showing the original suspension arrangement at Wikimedia Commons.

Incidentally, it is sometimes claimed that Telford sought permission from Sarah Guppy to use her 1811 patent for suspension bridges. Guppy's patent appears to have been for a catenary bridge, with the decking laid directly onto the suspension bridges, not for the type of bridge that Brown and Telford pursued. There seems to be little substance to this claim, but Telford certainly did rely very much on the assistance of others. Examples include learning from Brown's success in pioneering the use of iron chains; Hazledine's manufacturing capabilities; Telford's right-hand engineer William Provis; Peter Barlow's advice on the strength of iron; and Davies Gilbert's understanding of the mathematics of the catenary.

Telford's bridge encountered problems almost as soon as it was complete. Strong winds caused damage to the timber deck and to the hanger bars just one week after it opened. Remedial works were completed, but a storm in 1836 caused huge oscillations and significant damage, and then in 1839 another storm left the deck in ruins and the bridge impassable. Provis was employed to design a stronger, heavier deck.

Issues with wind on suspension bridges were by no means unique to Menai. Similar issues occurred around the same time on Samuel Brown's South Esk Bridge in Montrose, and wind-induced oscillation was also observed at Gattonside Bridge. Telford had not been unaware of the issue, and before the bridge was complete he was reported to have considered stiffening the deck with trusses, deciding eventually that if ever required, they could be retrofitted. The Menai Bridge was a giant engineering prototype, and as with any experiment, its performance was never entirely foreseeable.

The strengthened bridge lasted until 1893, when a new steel deck designed by Sir Benjamin Baker was introduced, largely to resolve problems with the deteriorated state of the timber deck. Further investigation and remedial work took place on several occasions before a decision was made that the bridge could no longer safely carry the loads required.

Between 1938 and 1940, the metal parts of the bridge were completely reconstructed, to a design prepared by Sir Alexander Gibb and Partners, and consultant Guy Maunsell. If the work had not already been underway, it's impossible to imagine it would have started once the Second World War began, given the quantity of steelwork involved and other demands for skilled labour. In any event the bridge was completed, but Maunsell was rapidly immersed in the war effort, turning his engineering skills towards sea forts and the concept behind the floating Mulberry Harbours. Due to the needs of wartime secrecy, his account of the Menai Bridge reconstruction was only published after the war had ended.

The masonry approach spans, which are themselves impressive structures, were left unaltered. Works were undertaken on the upper towers to slightly widen the portals through which vehicles pass. The masonry Bridge Master's House at the southern end of the bridge had its upper parts rebuilt to accommodate replacement of the suspension chains.

The suspension chain alterations included reconstruction of the anchorage elements hidden within tunnels at each end of the bridge. Temporary suspension cables were installed at the edges of the structure to relieve the load on the outer chains. The original sets of four chains directly above each other were replaced with sets of two chains directly above each other, with larger links in much stronger steel.

A new deck was constructed below the existing deck, to allow traffic to continue to use the bridge during the works. The existing deck was then removed (one lane at a time), allowing traffic to drive up and down ramps onto the lower deck. Once this stage was complete, the new deck was gradually raised into its final position. The original centre chains were removed entirely, with the only real evidence today of their existence being the empty slots in the face of the former Bridgemaster's House. The new edge trusses were then completed, considerably enhancing the load carrying capacity of the bridge.

I doubt that casual visitors to the bridge see it as anything other than Telford's structure. The profile remains the same, including the strange back-span arrangements where the chains are anchored directly down into the approach viaducts with hanger bars. Given the over-riding need to enhance the traffic capacity of the highway, the reconstruction was a relatively sensitive project. Even retaining chain catenaries was a technologically unusual choice in the mid-20th century: nobody was still building chain bridges at that point in time.

The trusses were foreseen by Telford, and don't mar the overall appearance of the structure, although the tacked-on cantilever footways are narrow and the new parapets feel over-tall. The detailing of the footway widening on the approach viaducts gives the impression that it was always there.

The bridge now provides one of the best viewpoints in the vicinity, and is one of the UK's most significant engineering landmarks. As with many such large bridges, it has come to define the character of the Menai Strait, visually structuring the way that visitors experience the area as well as remaining a key transport link.

Another bridge was built in 1850 to carry the railway across the Strait (later converted to become the main highway in the 1970s), and plans are under consideration for a third crossing. As with the Forth in Scotland, the prospect of a "family" of bridges is enticing, although it is too early to tell whether the new plans will be as visually successful.

Further information:

• Google maps
• Wikipedia
• Structurae
• British Listed Buildings
• Engineering Timelines
• Coflein
• Grace's Guide
• Bridgemeister
• Menai Heritage
• Menai Suspension Bridge: The First 200 Years (Daimond, 2019)
• A Walking Guide to the Menai Strait Bridges (Daimond and Kovach, 2015)
• An amateur's contribution to the design of Telford's Menai Suspension Bridge: a commentary on Gilbert (1826) ‘On the mathematical theory of suspension bridges’ (Calladine, Phil. Trans. R. Soc. A, 2015)
• Menai Suspension Bridge: a history of maintenance and repair (Day, ICE Engineering History and Heritage, 2012)
• Telford's Menai and Conwy suspension bridges, Wales (Day, Proceedings of the ICE, 2007)
• Performance of the Menai Straits Bridge Before and After Reconstruction (Billington and Deodatis, Restructuring: America and Beyond, American Society of Civil Engineers, 1995)
• The Secret Bridge (Richards, 1991)
• Menai Bridge (1818–1826) and its influence on Suspension Bridge Development (Paxton, Transactions of the Newcomen Society, 1977)
• Preservation of the Menai Suspension Bridge (Maunsell, IABSE 3rd Congress, 1948)
• Menai Bridge Reconstruction (Maunsell, Journal of the ICE, 1946)
• Life of Thomas Telford: The Menai Bridge (Telford, 1838)
• A Memoir of Suspension Bridges (Drewry, 1832)
• An Historical and Descriptive Account of the Suspension Bridge Constructed over the Menai Strait in North Wales (Provis, 1828)
• Description of the iron bridges of suspension erected over the strait of Menaï, at Bangor; over the river Conway, in North Wales; and over the river Thames, at Hammersmith; with views (Cumming, 1828)
• Particulars of the Grand Suspension Bridge erected over the Straits of Menai (Pring, 1826)

Staffordshire Bridges: 1. Ferry Bridge, Stapenhill

Don't get too excited by the title of this post: I only visited one bridge in Staffordshire recently, so the title is just in expectation that I may return and find others in the future. If you'd like to suggest any bridges in the area which I should visit, please respond via the comments to this post.

Historically, the River Trent formed the boundary between the counties of Derbyshire and Staffordshire, and a ferry served passengers between the town of Burton and the village of Stapenhill. In 1865, plans were laid for a bridge to replace the ferry, but nothing came of it until 1888, when Michael Arthur Bass, the 1st Baron Burton, agreed to fund the new crossing. His bridge was formally opened on 3rd April, the following year. In 1891, it was extended with an 81-span iron viaduct across the river's extensive flood plain (pictured).

The main river crossing is a suspension bridge with a main span of 120 feet and side spans each of 60 feet. It was built by local engineering firm Thornewill and Warham, who contracted Edward William Ives for its design. Ives, in turn, obtained the assistance of Alfred Andrew Langley. Suspension bridges were hardly new in the late 19th century, but Ives and Langley came up with something that departed significantly from what might then have been "normal" practice.

It's an unusual structure in two main ways. It is a self-anchored suspension bridge, where the main suspension "cables" are anchored not into the ground, but to the ends of the deck. There can't be many such bridges in the United Kingdom; the other examples that come to mind are Chelsea Bridge, built in 1937, and Derry's Peace Bridge, completed in 2011.

Ground anchorages are normal for suspension bridges because they allow the suspension cable or chain to be erected first, and the bridge deck to be assembled in sections afterwards. This minimises work within the river, to whatever is needed to pull the cable or chain across (and that can be done in stages) and to erect small deck sections. A self-anchored suspension bridge requires the bridge deck to be built first, usually necessitating extensive temporary works in the river. The choice here might have been down to poor foundation conditions within the river flood plain.

The suspension cables are also neither chains nor wire cables, but formed from riveted wrought iron plates. Bridges of this type are exceedingly rare, and the only other one I've visited is the 1910 Grunwaldzki Bridge in Wrocław, Poland.

The Stapenhill Bridge uses three layers of plates, one layer being jointed at each hanger position, so the strength is equal to two plates throughout. Judging from the bridge inventory at Bridgemeister, UK suspension bridges of this period were mostly built using wire cables, although some were still constructed using iron eyebars (e.g. Hammersmith Bridge, 1887). Perhaps the choice of riveted plates was driven by Thornewill and Warham's capabilities.

The suspension elements are supported on cast-iron towers. Although these are impressively ornate, they are are considerably diminished compared to the original structure - some historic photographs can be found on the Burton-upon-Trent local history website. Those show taller cappings both on the towers and at the ends of the bridge.

The bridge deck is supported from lattice trusses on each edge. These pass through the tower portals, with the result that the suspension "cables" are inclined inwards. This geometry imposes transverse bending on the lattice trusses, which is not the most efficient arrangement. The hanger bars are wrought-iron rods, except at midspan where there is a fixed connection between the chains and the edge trusses.

The deck itself consists of wrought iron transverse lattice cross-beams (through which service pipes are threaded), supporting timber flooring. New parapets have been added inboard of the main edge trusses: I guess this was part of the major refurbishment in 2016, with works designed by Inertia Consulting.

I'm not sure I could describe this as a beautiful bridge, but it is characterful, and good-looking in its refurbished condition. When I visited, the bridge and its approach viaduct were very well used, and hopefully it has a long future ahead.

Further information:

• Google maps
• Wikipedia
• Structurae
• Bridgemeister
• Engineering Timelines
• British Listed Buildings
• Grace's Guide
• The local history of Burton upon Trent
• ICE PHEW
• An Encyclopaedia of British Bridges (McFetrich, 2019)
• Civil Engineering Heritage: Eastern and Central England (Labrum, 1994)