24 July 2015

10 essential bridges books: 9. Calatrava Bridges

And so, we come to Santiago Calatrava.

Calatrava is something of a phenomenon in modern bridge design, and is often cited, quite wrongly, as being singlehandedly responsible for making bridges architecturally interesting. His designs are often immediately recognisable - his combined training as both an architect and as an engineer has led him to produce structures which combine visual drama with structural rigour, a kind of spacial poetics, usually writ large in tons of carefully balanced steel.

Calatrava Bridges (Tzonis and Donadei, Thames and Hudson, 272 pp, 2005) is ten years out of date now but remains the most up-to-date guide to this superstar's bridges, both built and unbuilt. As with most other books about the Spanish designer, it is in no sense a critical work, but is a celebration of his P.T. Barnumesque showmanship.

Calatrava's work is much-derided by other architects and engineers, if supposedly much loved by the public. Even the latter appears less true now, as he has a growing reputation for budget and programme over-runs as much as anything else. Fellow designers criticise the way that his bridges rarely respond to context, instead taking a signature style (white, generally steel, a cat's cradle of cables, hi-tech detailing) and dropping it into whatever setting is currently to hand. His bridges are bombastic, grandiose, sometimes over-wrought to the point where they become almost hysterical. Modesty and restraint are never Calatrava's watchwords.

However, as this book makes clear, Calatrava's work is also often geometrically fascinating, spectacular, and informed by a deep love of engineering craftsmanship and technology. That they are instantly recognisable puts other designers to share: he is the supreme bridge design stylist, happy to provide his signature wherever his clients are willing to pay for it. Few designers have been so prolific or so consistent, and if Calatrava has many unbuilt projects to his name, he also has far more completed works than most rivals.

Tzonis and Donadei's book is well illustrated, with plenty of beautiful photographs and quite a few diagrams and architect's sketches. It is not thorough in this regard - this is a good summary of the designer's work but certainly not the definitive encyclopaedia.

Reading through the book today, I am actually most struck by Calatrava's facility for concrete design. His unbuilt Vecchio Bridge would have been a particularly elegant, Maillart-esque concrete arch, while his 9 d'Octubre Bridge in Valencia features some exquisitely shaped curved concrete.

He is also occasionally capable of surprise, with his grey Oberbaum Bridge in Berlin and red-ribbed Ponte della Costituzione in Venice both being fine designs which are all the better for their departures from his usual palette.

A properly critical study of Calatrava's bridges has yet to be written, but until that happens, this book is at least a useful compendium of his work, and one that I am quite happy to recommend.

22 July 2015

Nine Elms - Pimlico Bridge Design Competition: Stage 2 Designs

Ok, here are the Nine Elms / Pimlico Bridge Design Competition Stage 2 designs in full. Click on any image for a full-size version, or visit the project gallery.

Ove Arup & Partners Ltd with AL_A, Gross Max, Equals Consulting and Movement Strategies

There has been a great deal of NIMBY-ish wailing from residents on the north bank of the Thames (and also from their political representatives), concerned that the bridge may wreak havoc upon one of the few public riverside green spaces in London, Pimlico Gardens. These complaints ignore the fact that this is a contest to select a team, not a design, and that no location for the bridge has been confirmed as yet. However, there's little doubt that an alignment between Pimlico Gardens on the north bank, and the new US Embassy on the south bank, is the most sensible.

Arup's design tries really, really, really hard to minimise harm to the gardens, siting the bridge's necessary cycle ramps in the river rather than on land. This makes for great public space, but is something of an imposition on the river, and it's hard to see how Arup deal with the inevitable issue of boat impact. As shown the ramps are structurally sketchy at best, slender loops of something-or-other with no visible means of support.

It's not an unattractive design, but, having visited the site, I don't think it is best served by having a tall structure mid-river, the riversides shouldn't be so visually dominated by a bridge. It's also not a straightforward bridge to build, with multiple angled and criss-crossing hangers, potentially requiring a great deal of temporary supports within the river.

Ove Arup & Partners Ltd with Hopkins Architects and Grant Associates

Arup, again, this time with a suspension bridge solution. This should, in theory, be much more respecting of the river environment, but for reasons that seem obscure, the designers have chosen to stretch the pylons far taller than is actually necessary, taller even than some pretty tall trees in Pimlico Gardens. By also painting them red, there seems to be an unnecessary dash of "look-at-me" all over this.

The ramps are, again, in the river, although the connection to the Gardens is less well detailed, punching through the middle rather than tucked discreetly into the corner as was the case for the previous design. However, this is the only design that recognises that the route is not fixed, showing clearly in the plans how the same bridge can be adapted to any number of alternative locations without affecting the structure's logic.

The circuitous ramps at least have some means of support, with cable stays radiating from the main pylons, but again they are vulnerable to boat impact and visually intrusive.

I'd also question the choice of deck structure, a steel multi-cellular box girder which seems unnecessarily expensive to me for a bridge of this span with suspension cables on both sides of the deck.

Bystrup Architecture Design and Engineering with Robin Snell & Partners, Sven Ole Hansen ApS, Aarsleff and ÅF Lighting

Bystrup's design shares the first two designs' offshore ramps, but does at least trouble itself to consider boat impact protection, with an "eco-pontoon", a planted floating fender, shown as a possible solution.

It's a cable-stayed design with an S-curved deck supported on opposite sides from the two towers, but I think the curvature of the deck is too slight, and this renders the cable and tower arrangements somewhat inert.

As with the second Arup design, a multi-cellular box deck is shown, symmetrical in cross-section, which make no real sense for a structure with cables on one side only at any given point - too much of the section's capacity is used to restrain its own self-weight torsion.

Buro Happold Ltd with Marks Barfield Architects, J&L Gibbons Landscape Architects, Gardiner and Theobald

Structurally, the Buro Happold design is by far the oddest of all these conceptions. It's an asymmetric cable-stay bridge, but the deck seems to be supported from a suspended cable net rather than from the usual array of stay cables. I found this baffling when the designs were first announced at Stage 1, and I find it baffling now. It seems to add a great deal of complexity for very little benefit, and it would be a nightmare to install and to maintain.

Even Happold's own construction diagrams make clear quite how unbuildable it is, with the main part of the deck requiring temporary props to actually hold up the cable net, even at at point when the cable net is doing nothing to hold up the deck. The deck is therefore temporarily supported along its entire length before being whizzed into position on a barge. This is simply not sensible or economic, given the alternatives available if a conventional cable-stay design were chosen.

It's the only design to dare to antagonise the NIMBYs by putting the ramps onshore, and I admire this. Pimlico Gardens is not, at present, a particularly impressive space, nor is it especially well-used, so it seems to be ripe for re-imagining, if, as this design suggests, the trees can be left largely untouched.

According to the competition website, design teams are now due to enter into "competitive dialogue" with the judging panel, and to submit final tenders (including a fee for their services) in early September. A winning team should be declared in October.

21 July 2015

Nine Elms - Pimlico Bridge Design Competition: Stage 2 designs published

The stage 2 entries from the 4-team shortlist for the Nine Elms - Pimlico competition have been published online, and are being exhibited in London until 24th July. There is also an opportunity for the public to offer feedback on the designs via an online survey, until the same date.

I'll write a more detailed post commenting on the designs when I get a chance later this week.

15 July 2015

10 essential bridges books: 8. Robert Maillart: Bridges and Constructions

If you're looking for a book about the great Swiss engineer Robert Maillart, then David Billington is your man. He's the author of Robert Maillart's Bridges (1979), Robert Maillart and the Art of Reinforced Concrete (1991) and the biography Robert Maillart: Builder, Designer, and Artist (2008). Maillart also features prominently in his The Tower and the Bridge (1985) and The Art of Structural Design: A Swiss Legacy (2003). If there's a number one Robert Maillart fan (and expert), it's quite clearly David Billington.

However, none of these is the essential book on the subject. That honour remains with Max Bill's Robert Maillart: Bridges and Constructions (1949; my copy is the 3rd edition, 1969, Pall Mall Press, 184pp).

Bill, an artist, architect and journalist, wasn't the first to recognise that Maillart's talent merited recognition beyond the narrow field of structural engineering. In the mid-20th century, a number of people were gradually recognising that the singular reinforced concrete constructions of the Swiss designer had merits beyond the purely technical. However, in choosing to write at length about Maillart's work, Bill played a key role in the designer's enduring fame.

The bulk of this book is taken up by documentation of many of Robert Maillart's key works: black-and-white photographs and generally short explanations in German, French and English. All his finest bridges are here, plus certain key buildings. There is much for the curious reader to consider, and although the text is generally brief, the overall impression is thorough. In contrast, Billington's books never really provide a comprehensive survey, but are significantly better in their analysis of Maillart's significance and his design methodology.

The reason Bill's book is still worth searching out secondhand is that it features a great deal of primary material. There are plenty of diagrams and design drawings, including reinforcement details, but also a number of Maillart's own writings are reprinted - I believe these are not otherwise available in English (the originals are available online at the Schweizeriche Bauzeitung archive).

Maillart was undoubtedly one of the true geniuses of 20th century bridge design - his reputation may have been hyped in recent decades, but it is certainly deserved. I suspect that he is the first name most bridge engineers will think of if asked to name a famous bridge designer of the period.

Bill's book remains valuable in returning the reader directly to Maillart's own words and designs, prompting the inevitable thought of how might the modern designer have drawn and built the same things, or things of equivalent quality. Reading Maillart's passionate defence of simplicity ahead of "accuracy" in calculation, it becomes clear that even today, few structural designers have such clear vision or self-confidence.

07 July 2015

10 essential bridges books: 7. 30 Bridges

Ardent pontists can satisfy their overpowering appetite for the latest, greatest bridges with any number of coffee table books, many of them utterly awful in their disdain for those who have laboured hard to make these bridges a reality. For example, I cannot really recommend Martin Pearce and Richard Jobson's Bridge Builders (2002), despite the many fine bridges it contains, since it relegates most of the engineering firms to a handful of footnotes at the end of the book. Similar concerns about attribution bedevil Chris Van Uffelen's Bridge Architecture and Design (2010), which also falls prey to the idea that a pretty picture defines a good bridge.

30 Bridges (Laurence King Publishing, 2002, 192pp) [amazon.co.uk], by Matthew Wells, is much better. Wells is a practising engineer, and an unusually literate one. Evidence of his unusually perceptive intellect can be found throughout the book's introductory essay, a brief history of bridge design. This touches on many of the obvious characters of conventional bridge-building history (Brunel, Strauss, Maillart etc), but is particularly good on the contingent element of history: its dependence on the specificity of individual projects, opportunities and individual actions.

Wells makes clear that history is not an orderly ascent of the mountain of progress, recounting the many failures which have punctuated our engineering past. He also situates bridge building properly within a broader context of economic drivers and technological transfer from other industries. Significantly, Wells' history is a critical history - he applies the understanding of his profession, as a structural engineer, but retains a careful distance to all that he recounts.

In his choice of 30 case studies, Wells seems at first to err towards the well known, such as the Gateshead and London Millennium Bridges, Pont de Normandie, Sunniberg Bridge, Punt da Suransuns, and Solferino Footbridge. Although he is hardly noted as a bridge designer, he boldly includes two of his own designs, the Plashet Grove School Footbridge, and the Royal Victoria Dock Bridge. What unites the bridges is that they are contemporary in nature, with the oldest dating to 1984, and that they offer the opportunity both to explain and to analyse.

Some of the examples are chosen to make explicit particular topics. So, for example the Helgeland Bridge, a major cable-stayed bridge in Norway, is used to explore the tendency in bridge engineering design to move away from generic loadcases and towards site-specific determination of traffic and wind loads. Design moves from a process of complying with prescribed rules to one of determining hazards and probabilities and enabling an informed judgement of tolerable risk.

Other bridges are used to illustrate points about how design ideas have developed historically, so that what present-day engineers consider appropriate is often constrained by its past evolutionary history - a feature also present in biological evolution.

As a critic, Wells is astute. Considering the work of Santiago Calatrava, he says "some works are fluent, while others seem overblown; all of them are immensely popular and accessible". He notes that one reason for Calatrava's ability to generate unorthodox structural form is that he does not draw primarily on the present and past of engineering, but is instead inspired by the flight of birds or other "poetic" visualisations. Later, he perceptively observes how "many of Calatrava's bridge are set up on their abutments, rather like a cake on a cake-stand".

I also admire his critique of the otherwise over-praised London Millennium Bridge: "Unfortunately, because the deck section is pared down to the minimum, the main cable arrays must be inflated into heavy bunches to cope with the highly distorted form, which results in the two elements approaching visual parity and conflicting with each other".

The two of Wells's own designs included in the book emphasise the advantages of an outsider's perspective. By virtue of not being a specialist bridge engineer, he is free to contemplate what those more firmly ensconced in the tradition might not, resulting in numerous unusual but thoughtful details on both structures, and in the kit-of-parts approach to the assembly of the Royal Victoria Dock structure.

The book is well illustrated with photographs and diagrams, but also with the author's sketches, intended generally to try and explain structural engineering principles and details. Non-specialist readers will learn far more from 30 Bridges than from most of its coffee-table competitors.

Overall, the strength of the book is its willingness to critique rather than simply to depict, to try and get into the guts of the various bridges and understand what makes them work well, work poorly, or just work differently. There are very few voices from within the structural engineering profession capable of producing anything similar, which is a shame.

Wells has also authored Engineers: A History of Engineering and Structural Design (2010), which I also happily recommend, especially to those (the majority) ignorant of the development of their own profession.