Bridges, bridges everywhere

Materials World magazine
,
3 Aug 2015

Bridges are making headlines all over the UK, as innovative and exciting new engineering projects abound. Rhiannon Garth Jones finds out more.

In a world full of exciting megaprojects, the humble bridge might still be king. Traditionally, cities were built next to rivers, and rivers need crossing. From the dawn of civilisation, engineers have been putting their minds to bridge building. The basic, functional types that allowed armies to cross rivers in pursuit of their enemies were expanded into monuments to form and function by the Romans, before catching the public imagination once more during the Industrial Revolution. Now, in 2015, bridges are catching the attention of engineers and the public once more. 

Until 1729, with the construction of the Putney Bridge, there was only one crossing of the Thames in London. There are now 33, and more on the way. You’d be forgiven for thinking that the Garden Bridge was the only new one, but the others are just discussed less. Wandsworth Council is currently deciding between four designs for a pedestrian and cycle crossing between Pimlico and Nine Elms, by Buro Happold Ltd, Bystrup Architecture Design and Engineering, and two from Ove Arup & Partners Ltd. The winning design is expected to be announced in Autumn 2015. 

Elsewhere in the capital city, Expedition Engineering is currently working on a 170m-long bridge to connect Imperial Wharf and Chelsea Harbour to Battersea. The three-arch bridge will be named the Diamond Jubilee Footbridge, should receive no public funding and will be open 24-hours-a-day. Meanwhile, the Thames Gateway Bridge, which was first suggested in 1943 before being finally cancelled in 2008 (with some rollercoaster ups and downs along the way), is now under consideration again. 

Far from the commotion and controversy surrounding London’s Garden Bridge, in the Lake District, artist Steve Messam built a bridge using only paper. Specifically, he used 22,000 sheets of poppy-red paper and no glue, bolts or other fixing to create a waterproof, weatherproof and weight-bearing bridge. The installation used the architectural principles of dry stone walling, common in the region, to provide strength. Messam says, ‘The technique just works. I used blocks of paper, 100–200 sheets at a time, and then wedged them in with shorter pieces. The gabions either side were built up by wallers to make sure they were rigid and compact as well as looking nice. All the stone came from the immediate vicinity to blend in with the general palette of the landscape and not stand out, allowing the bridge to take all the visual impact.’ The bridge is now closed, but it’s unusual colour and use of materials means it’s likely those who tested its stability will remember it for some time. 

Messam is not alone in focusing on traditional building techniques. The proposal for the new Bristol Downs footbridge is a classical stone footbridge, drawing on the skills of local stonemasons, while providing training for apprentices. Researchers from the University of the West of England have worked voluntarily on the project for over a year, together with partners from the Friends of the Downs and Avon Gorge. The engineer, Dr Adrienn Tomor, has previously stressed her intention to use ‘traditional techniques with modern technology wherever possible’. If the project were successful, it would be the first large stone bridge built in Europe for more than 100 years. The benefits, to many, are obvious – as well as being visually impressive, masonry arch bridges have proved to be highly sustainable structures over the centuries and, while they might be initially more expensive, cost far less in long-term maintenance. It is also hoped that the structure will generate tourism, and create a local speciality. 

In Reading, a more modern approach is being taken to the construction of a £5.9m pedestrian and cycle bridge over the river Thames. The bridge, due to open this summer, has a 11m steel mast connected to the cables that support the deck. The steel sections for the bridge, and the mast, were all made in Rotterdam, the Netherlands, before being shipped to the UK.  

And that’s by no means the end of the story for bridges in the UK. Campaigners are still working with engineers to make two megaprojects viable – a third bridge across the Menai Strait, to connect Angelsey and North Wales, and a long-mooted crossing of the Irish Sea. Although neither is by any means certain, the engineering challenges they would provide would certainly be fascinating.