01 July 2008

"Footbridges" by Mike Schlaich & Ursula Baus

"Footbridges" (ISBN 978-3-7643-8139-4, Birkhäuser Verlag, 2008) [Amazon UK] is subtitled "structure - design - history". While those three little words may seem fairly obvious, this first ever major survey of fussgängerbrücken is unusual amongst coffee-table gephyrophilia in that it does actually address how (foot)bridges are designed, not just what they look like. And understanding whether a bridge design is any good relies in great part on understanding why it is how it is.

In large part that's because coauthor Mike Schlaich is a practising bridge engineer, son of the more famous Jörg Schlaich, but also a widely recognised and respected figure in his own right. In many ways, "Footbridges" is the glossy layperson's companion to the more technical "Guidelines for the design of footbridges" (Fib, 2005), for which Mike was the lead author, and which spotlights several of the same structures.

The book includes a lengthy (40-page) history of footbridge design and construction, covering key figures such as Jean-Rodolphe Perronet, Ulrich Grubenmann, Guillaume Henri Dufour and the ubiquitous Robert Maillart. This is no small thing, as the history of footbridges is to a great extent the history of bridges - the earliest timber, stone and rope bridges were all footbridges, and many of the great experimental developments in bridge engineering were first attempted on footbridges, particularly the earliest suspension bridges. This historical survey introduces several great structures both well-known and little-known, with great photographs, such as the Seguins' pioneering Annonay bridge, now in a state of seemingly terminal disrepair. I particularly enjoyed the coverage of vernacular bridge designs that were unremarkable historically but widespread, such as David Rowell's suspension bridge at Ilkley, one of a number of similar structures that dot the British Isles (and beyond).

The bulk of the book is taken up with descriptions and photographs (all taken specially for this book) of selected modern footbridges around the world. These include elegant designs by several of the greatest bridge engineers, such as Riccardo Morandi, Fritz Leonhardt, Ulrich Finsterwalder, René Walther and Jiri Strasky, those five just from an early 18-page stretch. There are bridges that are remarkable, beautiful, puzzling and inspiring, as well as one or two (such as Arup's Kingsgate Bridge) where the merits are much less clear. There are several works of sheer genius (including three by Jürg Conzett and several by Schlaich's own firm, SBP). There's an obligatory Calatrava (Campo de Volantin) and a good sampling of Wilkinson Eyre's oeuvre, but my favourites include a selection of relative obscurities - a delightful spider-web suspension bridge over the River Esk in Scotland; a glass garden bridge near Nice in France; a combination bridge and park bench in Baruth in Germany formed from curved oak slats; and an ultra lightweight suspension bridge over the Maggia valley in Switzerland.

Schlaich and Baus have identified so many great footbridges that there's an entire chapter devoted to dozens of shorter portraits, including older structures, many of which would have merited three or four pages if space permitted, being every bit as good as the bridges given full coverage. Unfortunately the space restrictions limit the photographs in these pen-portraits to very small monochrome images, which struggle to do justice to several excellent structures.

Although the authors initially seem to have a good critical eye, I think they are too restrained in many instances, with bridges ripe for criticism given the kid-gloves treatment. For example, London's Millennium Bridge, so often described as a "blade of light", is suggested here to be "probably the most delicate suspension bridge of our time". Am I the only person who finds it an over-engineered throwback to 70s high-tech architecture, marred by an ungainly and arrhythmic array of outriggers, dampers and cable fixings? Or that the Royal Victoria Dock bridge is a white elephant which struggles to match its remarkable superstructure to an appropriate means of support below? There are numerous other bridges where gentlemanly restraint has triumphed over the possibility of a less deferential critique.

Spliced in between the bridge portraits are a series of short pieces on key issues in the design of modern footbridges - stress ribbon structures; dynamics; curved ring girders; and moveable bridge types. I find it hard to judge how informative these will be to the non-technical reader, as they don't entirely manage to avoid mathematical formulae and force diagrams, but they do at least attempt to explain that the better bridges are the product of the careful consideration both of structural behaviour and construction methods, rather than just a pretty curve or gesture.

Overall, "Footbridges" is an excellent survey of a wide range of interesting structures, many of them not covered in other recent coffee-table assaults on the contemporary bridge (by Wells, Arcilla, Pearce and others), with plenty of excellent photographs that make you want to grab an atlas and plan your next holiday itinerary accordingly. For the professional bridge designer as well as the lay bridge enthusiast, this is not a book to sit proudly on the shelf, but to keep well-thumbed and close at hand.

2 comments:

Ranger Bob said...

Am I the only person who finds it an over-engineered throwback to 70s high-tech architecture, marred by an ungainly and arrhythmic array of outriggers, dampers and cable fixings?

No. Next question, please.

Or that the Royal Victoria Dock bridge is a white elephant which struggles to match its remarkable superstructure to an appropriate means of support below?

This one I have to think about for a while.

Seen in photograph, it certainly takes one up short, but I'd be really curious to see how it comes off in situ. My mind turns immediately to the Tower Bridge or Telford's suspension bridge at Conwy Castle- spans whose design could be criticized from a purely functional perspective, but seem to fit well into their surroundings.

Knit Nurse said...

My opinion of the Millennium Bridge is that while it looks rather delicate in its side elevation, it is lumpy and ugly when you are crossing it, and the cables mar the views of the river.