"Leicht Weit / Light Structures"

Jörg Schlaich & Rudolf Bergermann's "Leicht Weit / Light Structures" (Prestel, ISBN 3-7913-2918-9, 2005, 328pp) [amazon.co.uk] is a mammoth coffee-table slab documenting the ever-fertile genius of one of Germany's best known design firms. It came out a few years ago now, an offshoot of a series of exhibitions of Schlaich Bergermann's work held in 2003 to 2005, but I re-read it recently and it more than deserves a mention here.

Schlaich and Bergermann began working together in 1968 in the office of Leonhardt und Andrä, collaborating on a number of television towers, and lightweight structures such as the Munich Olympic stadium roof. In 1980, they set up their own firm, Schlaich Bergermann und Partner. Schlaich had followed his mentor Fritz Leonhardt in becoming a professor at Stuttgart University, and was as prodigious as Leonhardt in his ability to bridge consultancy and academia, contributing to a staggering range of innovative designs.

Presented throughout in dual German and English, the book marries a series of essays with a lengthy survey of SBP's work written by Annette Bögle. The chapter headings give a good idea of quite why SBP are so important: concrete towers; cable net and steel lattice towers; concrete shells; cable nets; grid shells; textile membranes; air-inflated roofs; cable-suspended roofs; highway bridges; railway bridges; footbridges; solar power plants; and more. If they ever deign to descend into the world of mundane civil engineering, little trace of it is to be found in this book.

The essays are generally illuminating, and include contributions from luminaries such as Marc Mimram and David Billington. An interview with Schlaich offers amusement when he is quoted as describing the "wild ones" who "outdo each other with puffed up and squashed blobs, often just satires and caricatures of misinterpreted 'role models' - with no connection between form, function and flow of forces". This is juxtaposed with a picture of a Frank Gehry building design, surely the antithesis of this statement - although, of course, Gehry has often collaborated with SBP.

Schlaich's own essay on lightweight construction identifies it as important for its combination of social, ecological and economic benefits, while clearly noting that it has limits including the paradox that the lightest weight permanent form often requires the heaviest construction methods to build. However, Schlaich sees this as an advantage, particularly where increased labour costs are recognised as beneficial due to the increased employment generated.

Indeed, the essay exemplifies his engineering ethic quite clearly: socially and environmentally aware, an attitude seen both in their early Hooghly Bridge design, with its multitudes of rivets well-adapted to local working requirements, as well as their recent keen interest in solar power structures, and their potential to alleviate energy-poverty at low cost.

"Light Structures" is copiously illustrated with both photographs and diagrams, and the structures included are generally well explained. Most of their best bridges are included although there are some curious omissions such as the Löwentor cable-net footbridge and the Obere Argen Valley Bridge.

Both those were, however, well-covered in Alan Holgate's "The Art of Structural Engineering: The Work of Jörg Schlaich and his Team" (1997), another bulky coffee-table monograph which could be considered to be either competing or complementary. Hopefully I'll cover that one on another occasion.

"Leicht Weit / Light Structures" is an essential book for anyone interested in innovative structural engineering. It's well written and well illustrated, and an excellent survey of some of the most innovative work of the late twentieth century, including in the bridge engineering field.

Bridge competition debris part 12: River Wear

The River Wear Crossing bridge design competition will need little introduction to regular readers: I've covered the outcome extensively on several occasions here.

Organised by RIBA on behalf of the regeneration company, Sunderland Arc, the competition sought a design for a highway bridge across the River Wear, with the organisers being quite explicit that they were looking for something iconic. The winning design (pictured right), by Techniker and Spence Associates, is currently undergoing further technical development before Sunderland City Council decide whether or not they can afford it.

I've been keen for some time to publish the other entries, the five designs that weren't chosen. H0w is the winner to be properly judged if not against its peers? Sadly, Sunderland have refused to release images of the other entries, and my enquiries with the designers have, with the two exceptions shown below, drawn a blank.

Three losing entries came from Halcrow, Flint and Neill, and Dissing + Weitling; Hyder and Yee Associates; and Jacobs Babtie, Leonhardt Andrae und Partner, and Marks Barfield. I would love to show you these, so if any of the designers would like to send through their images, please email happypontist at googlemail dot com.

The other two losing entries are shown below courtesy of Schlaich Bergermann, and Wilkinson Eyre. How do they compare against the winner?

In many ways, all the designs share a desire to adopt an unnecessary and inefficient structural form purely to shout "look at me". That's not unreasonable - I think it's a large part of what Sunderland were looking for.

The Gifford / Wilkinson Eyre design is far more economic than the winning entry, with a cable layout that doesn't impose too many unnecessary forces on the support tower, particularly in the way the cables are arranged in plane with the axis of the V-shaped pylon arms (minimising bending moments).

That V-shaped pylon itself, of course, runs the risk of being seen in Sunderland as a two-fingered salute to local rivals such as Newcastle - see, our bridge is bigger, better. I can't help thinking the basic geometric idea (the X-shaped pylon and cable arrangement) doesn't quite make sense here, but could be developed into something interesting on a different site.

The images of the Schlaich Bergermann entry are a real curiosity, as much for the insight into their creative process as for the unlikely solution itself, a combination asymmetric cable-stayed suspension bridge, from which giant glass scales are suspended. Gehry doesn't strike me as an architect with much sympathy for the normal imperatives of bridge design - his work is about shape and surface rather than structure, and his non-linear, protean forms are at odds with the linear, refined forms normally suited to bridges. Jörg Schlaich, on the other hand, is a giant of engineering notable for pushing the boundaries of structural innovation without normally departing from the primacy of his structural ideas.

The Gehry / Schlaich design for River Wear seems to have its origins in Schlaich's 1989 Neckarstrasse footbridge, albeit at a larger scale and with the reverse suspension cable (the one that curves out of the tower like a letter D) much improved in shape. The only similar design I can recall seeing is Robert Benaim and Powell Williams's design for the Royal Victoria Dock bridge. Like that bridge, my first thought is about the difficulty of cable replacement once in operation.

Gehry's glass scales simply aren't my cup of tea, they seem like an afterthought, and I can easily imagine the judging panel worrying about both how they'd be restrained, maintained, and protected against damage. I do, however, admire the way that Gehry brought something so unpredictable to the design.

So, if you had to choose between these three designs, which would you choose, sat in Sunderland's shoes?

As with all these posts, click on an image for a full-size version.

Gifford / Wilkinson Eyre


Schlaich Bergermann / Atkins / Gehry Partners