Transcending history

Words by Fiona McGowan


A staggering feat of engineering and architecture creates a physical link between Cornish history and Arthurian legend.

Image courtesy of David Levene


The legend of King Arthur is inextricably connected to Tintagel, whose clifftop ruins draw tourists year-round to the English Heritage site in north Cornwall. Tintagel was first mentioned as the place where Arthur was conceived in Geoffrey of Monmouth’s 12th century tale of a king who ruled the country with a heady mix of magical fantasy and military derring-do. Since that story, written around 1130, Arthurian legend has been expounded and revived countless times – becoming so much part of the English literary canon that you’d be forgiven for thinking that Arthur was a real person, albeit embellished with magical powers.


The fantasy place of Arthur’s conception has taken on a life of its own, too – Richard, Earl of Cornwall built his own folly of a castle on the site in the 13th century, presumably partly because of its infamous connections to the great imaginary king. It is not just a place of mythology, though. Tintagel was once the seat of the kings of Dumnonia – one of the great strongholds of ancient Brittonic tribes, who regained power after Roman withdrawal in 410AD and ruled for several centuries until the region was eventually absorbed by England in Medieval times.

Today, myth and reality play a big part in a visit to the rugged clifftop ruins. The great crag of a headland is connected to the mainland by a low isthmus. Centuries of erosion have caused the pathway to have dropped, meaning that, until this summer, the island ruins could be accessed only by a series of steep steps. English Heritage, custodian of the site, decided to re-integrate the two elements by building a footbridge to enable easier access to the island site.


Back in 2015, English Heritage held a competition to find the best bridge design for this plan. Of 137 entrants, English Heritage selected seven competitors to submit a formal proposal, and finally chose the designs of a collaborative team: Ney and Partners, a Belgian architecture and engineering company with a track record of building striking bridges around the world, and young British architect William Matthews. Matthews and Ney had worked together on plans for a bridge project in Italy earlier that year, says engineer Matthieu Mallié, and discovered that they had excellent synergy, so when William drew their attention to the Tintagel project, they jumped at the chance: “There is a strong sense for design in engineering in the UK, and we had never worked in the UK before,” explains Matthieu, “so when William contacted us about Tintagel, we saw that the location is beautiful and very interesting, so we decided to brainstorm with him to create a proposal.”


English Heritage went for the Ney/Matthews designs, and the two practices formed a team to tackle the challenges of the project. While the team was officially led by Laurent Ney, Matthieu is keen to emphasise that it was a democratic collaboration, with each team member adding their own views and technical expertise. “We joined both forces from the beginning. Laurent was originally a civil engineer and later on gained the title of ‘architect’. Myself, I am an engineer – I know how to compute a bridge; I understand the loads on a bridge; I know what elements constrain the dimension of the design of the bridge. William may have an intuition about the way it works and the flow of forces, but he’s an architect, so he’s concerned about landscape integration, architectural details and materials.”


Image courtesy of David Levene

Image courtesy of Jim Holden


The constraints of the site were the first challenge. Since the beginning of human existence, we have been coming up with different ways to span gaps: “Bridges are necessary for mankind,” Matthieu says emphatically, “to link people together. That’s a need. It’s not a pleasure…” The aesthetic challenges are one thing – building a 60m span that is sensitive to an unspoilt, craggy coastline, not to mention an important architectural site. But the technical and logistical challenges are another completely. Walking across the bridge today, very few visitors would pay too much attention to the fact that this is quite some feat of engineering.


They wouldn’t consider how you transport the materials for this big steel structure, when there is no road access to the ends of the bridge. Perhaps you might imagine that giant scaffolding was built up from the valley floor, and the steel pieces were winched up and put into place. None of this was technically possible. There was no access by road to bring huge pieces of steel, the span is too high for scaffolding, the sea is too far away to bring the steel by barge… At first, the engineers considered using big Super Puma helicopters – the sort that are used to build off-shore oil platforms – but there were too many variables: not least because the area is protected for fulmar breeding at certain times of the year, and the fact that you have to book the helicopters for very specific time slots. Miss your slot and you might have to wait six months for the next availability!


Images courtesy of Jim Holden


It was William Matthews who came up with the idea of using a cable crane – a massive cable car that slides back and forth across the gap with building materials. They are most commonly used for building ski stations, but the system translated perfectly to the remote Cornish coastline. Admittedly, says Matthieu, it meant that the bridge had to be built in much smaller pieces than this sort of structure usually requires. And then there’s the actual physical build. While the bridge looks fine and delicate – almost filigree, thanks to its criss-crossing slim trusses and slender curving banisters – it’s still 50 tonnes of steel, not to mention the weight of the slate decking. The non-engineers among us might wonder how you go about building a bridge of that weight in the first place. There are various ways you can do this, explains Matthieu, but he and his partners plumped for a cantilever build in the style of the iconic Forth Bridge in Scotland.


It is built outwards from an anchor point in the cliff, and each section is essentially self-supporting. Imagine, if you will, a Lego bridge, with each piece sticking securely to the next. The cantilevers on each side of the span are built independently – each four-tonne piece of steel made entirely secure before the next piece is attached. Needless to say, the anchors in the cliff need to be incredibly strong, but the system is such that the bridge build could stop part-way through the process, and nothing would fall down.


It is for this reason that the two sides of the bridge don’t actually need to meet in the middle. And in fact, they don’t. There’s a 4cm gap of pure air in the middle of Tintagel’s footbridge. It’s been designed to enable the bridge to expand in the heat, but the gap has deliberately been put right in the middle, in some ways to represent the journey between myth and reality, from the solidity of the mainland to the fantasy of the Arthurian legend on the headland. As Matthieu says: “We had the opportunity to transform a technical feature into a poetic feature.”


Image courtesy of Justin Minns


There are many other interesting elements to this footbridge – not least the dedication to using sustainable materials. Ney and Partners makes every effort for their designs to have a minimal impact on the natural environment. Steel, though requiring high-energy production in the first place, is a long lasting material, and is relatively light for its strength, meaning less material needs to be used, rather than, say concrete. The decking is made of thousands of vertical slithers of slate, stacked into steel trays. The upended slates form a very grippy surface, but more importantly, they are locally sourced. English Heritage opted to use slate from Delabole mine, just a few miles from Tintagel, rather than buying cheaper slate from India or China. “It was great to have a client who is as interested in the environmental concerns as we are,” says Matthieu. “The Delabole slate was more expensive, but in terms of durability, the environmental impact and the impact on the local economy, it was a great decision.”


The bridge design itself was as minimal as possible, both in aesthetic and environmental impact. Matthieu explains that the shape of the bridge – with its arched top and counter curve in the base – creates a combination of traction and compression forces that enable a lighter, more minimal structure, considering the length of the span. The five rock anchors on each side are deeply bored into the ground and are completely invisible. Admittedly, the concrete that surrounds the rock anchors on the cliffs has quite some visual impact, but its scar-like effect will no doubt mellow with time.


English Heritage has created this visitor attraction with the aim of drawing together the myths of the great fantasy king, Arthur and the genuine archaeological intrigue of a land of Cornish kings – all in one of the most magical settings in the country. The bridge that now spans the chasm between headland and mainland almost perfectly embodies that concept.


english-heritage.org.uk

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