Footbridge 2017: conference report Part 2

Footbridge 2017 had a number of keynote presentations from "big names" in the pedestrian bridge design community: Dietmar Feichtinger, Jan Knippers, Marc Mimram, Jiří Stráský, and Keith Brownlie. For me, the highlight of these was Brownlie's presentation on "Taste (a world of difference)".

Brownlie's design experience spans the globe, and he chose to draw attention to the way in which different styles of bridge design are accepted or promoted in different locations. The aesthetics of bridge design is a topic which has, by now, been pored over extensively, often by engineers seeking to establish a framework of guidance for colleagues. I discussed some of this back in 2009.

However, the issue of taste, the subjective evaluation of aesthetics, has been addressed only in passing. One example that comes to mind is Colin O'Connor's 1991 paper reporting on a series of surveys on bridge aesthetics made with the Australian public. However, the whole issue of what the public think of bridge aesthetics is often ignored by professionals.

Brownlie presented a number of bridge examples from around the world, both built and un-built, loosely tying these together with the thesis that one major determinant of taste is climate, specifically the possibility that 'latitude' correlates with 'attitude'.

Northern-latitude examples include the startling (and, I think, depressing) sobriety which informed the various finalists in the Nine Elms to Pimlico bridge design competition, as well as a number of Nordic designs which are united by their dislike of colour and complexity. At the opposite end of the scale are projects in hotter climes, such as Singapore's bling-laden DNA Helix Bridge (photo courtesy Angelo Pereira), the exuberant Swan River Footbridge (more on this piece of faux-iconic infrastructure some other time, perhaps), or the unsubtle and over-wrought winning design in Miami's I-395 Bridge design contest.

Brownlie's message was simply that the idea of objective aesthetics should be treated with suspicion, and that taste should be acknowledged if not always embraced. He noted that "taste is an ever evolving force", and this is the point I found particularly interesting.

The examples in the paper are all recent designs, largely post-millennial, and so offer a snapshot of current taste. It's easy to find exceptions to the trends set out, but I was left wondering how international tastes in bridge design have emerged, spread, changed, or declined.

One thing that unites Brownlie's examples is that they have been designed and built within a post-modern era. They are not generally representatives of a post-modern philosophy, but they share post-modernism's freedom of treatment of colour, form and style. Playfulness in design has also been greatly facilitated by technological developments, and by economic surplus. This, I think, is one thing that has given rise to the present variety of international taste, and I suspect that economic wealth can also be shown to be prime driver in adoption of some of the more outlandish designs seen in recent decades. Poorer countries generally can't afford to depart so far from pragmatism.

Rationalism is in widespread retreat, and with it the adherence to functionalism that united modernist design. If you look back at many of the nations that Brownlie references, older designs show greater unity. Australia's current taste for the exuberant and irrational (Swan River and Kurilpa Bridge, the latter pictured above left courtesy of Jan Smith) would have been foreign to earlier generations, who had yet to escape the more traditional views inherited from colonial times. The degree of unity seen in the designs of Sydney Harbour Bridge (pictured right), Hell Gate Bridge, and Tyne Bridge is an example: form driven by the practicalities of technology, by the constraints of economy, and by the desire to match form to function.

I think there is also an issue of the desirability of expression of taste, which Brownlie does touch upon, suggesting that in the absence of familiarity with good design, American audiences "literally have no taste". The same is true, I've observed, in Australia, which shares America's frontier heritage: focussed on outcomes, narrow in vision. The result in both nations has often been infrastructure entirely free from any notion of aesthetics, and the current trend towards the overly demonstrative in bridge design in both nations might be seen as a simple over-compensation to their historic cultural deficit.

I think one reason that these developing nations (USA, Australia, along with the Middle-East, much of south-east Asia etc) espouse the irrational, the gigantic, and the frivolous is that they feel left behind by those cultures whose historical continuity has given them a privileged position in the hierarchy of taste. In striving so hard to escape their own inferiority complex, they have ridden a pendulum well beyond what most European cultures would consider tasteful. It is a self-conscious imitation of prestige, almost the very definition of "bling", with inevitable results.

Fashion, in the sense of 'designer' clothing, is increasingly international, with a global audience looking in many cases beyond local tradition towards international brands exhibited in Paris or Milan. The 'brand' influence on taste is less visible in bridge design, with the notable exception of the work of Santiago Calatrava, once (unfairly) derided as the "McDonalds of bridge architecture". Bridge design is inevitably more contextual than fashion, forced by immobility to relate more closely to constraints of geography, climate, history and culture. However, Calatrava makes clear that there is space for brands to set and influence local taste, and indeed I think many of the "exaggeratedly structural" bridge designs seen around the world show the power of the Calatrava brand itself.

In the buildings community, the likes of Gehry and Hadid suggest a wider international acceptance of brand-led design taste, an admiration for freeform extravagance that parallels Calatrava's position closely.

Should designers respond to taste, or look to influence it? Few bridge designers have, or will ever have, the profile of a starchitect. Many espouse a humility and sobriety which is at odds with wider public taste and so are very unlikely to influence it.

Change comes at the point of intersection between design and its recipients, where trends, fashions, philosophies can be influenced or be rejected. Presentation of a compelling vision or a narrative can be powerful. The Footbridge conferences are a great place to cultivate this debate, but the public cannot or do not participate, and clients are also notable by their absence. The difficulty of engagement between the public and those employed to design their environment is nothing new, of course, but I do wonder whether there's a way of getting better public input and understanding not only of specific project issues, but also of wider aspects of aesthetics, value and performance.

Footbridge 2017: conference report Part 1

Every three years, the bridge community gets together to discuss developments in the world of footbridges. Previous events have been held in Paris, Venice, Porto, Wrocław, and London, and this year it was Berlin's turn. I’ve reported on the Wrocław and London events here on this blog.

These are always amongst the most enjoyable events in the conference calendar, largely because they are (in line with their theme) a great opportunity for spanning borders and making new connections. I've met many interesting people at Footbridge conferences, and the problem now is that there are simply too many presentations to see and too many people to meet within the time available.

This year's event was held in the Technical University of Berlin, in one of a series of large buildings originally built for the AEG company. The exhibition part of the conference was located in the Peter Behrens Hall, a giant space now normally used as a structures laboratory. It's a lesson in humility for Anglo-Saxon attendees, as the space showcases the close and purposeful collaboration between industry and academia that is less often found outside mainland Europe.

Tucked away throughout the hall are little experimental concrete-shell bridges, bridge models built by students, and their pride-and-joy, a carbon-fibre supported stress ribbon bridge which was being used during the conference to demonstrate active vibration control mechanisms (see photo, right).

This year, the conference expanded beyond the usual array of technical papers and case study presentations by organising a bridge design "competition", Footbridges for Berlin, with attendees invited to submit their ideas for a bridge at six sites within the city. These have been collected together in a book ("The world’s Footbridges for Berlin"), which I'll review in more detail in a later post.

The presentations of these bridges gave several people the opportunity to explore creative directions that they would normally avoid, as well as the chance to cultivate critique and debate. Unfortunately, this stream was presented at one end of the exhibition hall, a space simply too large and echoing for this to work as well as might have been hoped.

There were some very interesting keynote presentations, most notably the two which departed most from the conference's putative topic. Film director Robert Schwentke presented on how to "tell a story" (addressing the continuing need for designers to improve how they communicate), while photographer Wolfgang Volz gave a splendid overview of Christo and Jeanne-Claude's Floating Piers project. Both these topics reminded all those present of the need to lift their heads up from day-to-day concerns, and consider how to better address the wider world for whom the minutiae of design and construction is irrelevant.

One thing that struck me about the keynotes was that all the presenters were white, European men. In line with the conference as a whole (and much of the wider bridge design and engineering community), this is not a diverse group, and not well aligned with those who enjoy or endure our output. I'd seriously hope that Footbridge 2020, to be held in Madrid, might try to do better.

One positive development is that the conference papers will be made available online (via Structurae) in six months time. I think this is a brilliant move, as far too often conference proceedings are difficult to get hold of, acting as a bar on sharing knowledge more widely. Perhaps other conference organisers could consider adopting a similar approach, as the whole industry's track record on availability of published research and case studies remains very poor.

Ok, that's enough for this post. I'll put together one or two follow-up posts to look in more detail at some of the more interesting papers presented at the conference.

Footbridge 2017 reminder

We're getting close to the end of the year now, which means this is probably a good time to remind any interested readers about deadlines for the Footbridge 2017 conference.

The conference will take place in Berlin next year from 6th to 8th September. The organisers are hoping to take the event in different directions to previous Footbridge conferences. As well as papers on innovation and dynamics, they are particularly looking for submissions which "tell a story" about a design or perhaps a new material or construction idea. They want contributors not just to share the facts, but explain their learning, to discuss not only their own work but enter into debate with others. It has the potential to be much more interesting and inspiring than a conventional conference.

They're also running an open request for design submissions, having identified six sites in Berlin where no footbridge is currently planned, but where one could be considered. It's not a competition as such, but a way to inspire creative contributions, which may be featured in a special book to commemorate the exercise, as well as discussed at the conference itself.

I'm particularly pleased to see that they plan to publish the conference papers freely online in April 2018, which I think is an excellent initiative.

The deadline to submit abstracts or to register to submit a design is 1st January 2017.

Bridge: The Heritage Of Connecting Places And Cultures

There's an interesting conference planned for 6th-10th July 2017, to be held at the Museum of Iron, Coalbrookdale, UK.

It's organised by the Ironbridge International Institute for Cultural Heritage (based at the University of Birmingham) and the Ironbridge Gorge Museum Trust, and is intended as an interdisciplinary conference examining the heritage of bridges. The organisers state that "the conference will draw from anthropology, archaeology, art history, architecture, engineering, ethnology, heritage studies, history, geography, landscape studies, literature, linguistics, museum studies, sociology, tourism studies etc."

Proposed discussion themes include:

• The materials and technologies of bridges – the heritage of form and function
• National and local iconographies of bridges
• Narratives of bridge construction and destruction
• Communities united and communities divided by bridges
• Poetics of the bridge – representing the bridge in art, literature and film
• Love and death on the bridge
• The language of the bridge – metaphors and meanings in social life
• Touring bridges – travel narratives and tourism economies
• Alternative bridge crossings – tunnels and ferries

A call for papers has been announced, with a deadline of 1st November 2016 for abstract submission. There are no details on conference prices at present., but you can visit the conference website to keep up to date with plans.

Seminar on pre-designed bridges by Mario Guisasola, London Friday 10th June

My London-based readers may be interested in this seminar, organised by the Imperial College CivSoc, which takes place from 12-1pm, Friday 10th June, Room 207, Skempton Building, Imperial College, London.

Mario founded design firm Anta IC in 2003, and has designed a number of geometrically interesting and innovative bridges. such as the example depicted above. These are all bridges where the formal geometry is derived from consideration of the span's internal forces, and I've been hoping for some time they'll get some greater attention, so this is a good opportunity to find out more about them - there's also plenty of information on the Anta IC website.

The great debate: Who owns bridge design?

I've been in Bristol and took the opportunity to attend this debate, held at the Arnolfini as part of the Architecture Centre's Bridge150 season, celebrating 150 years since the inauguration of Brunel's Clifton Suspension Bridge.

The debate was set up as architects against engineers, but from the start you could tell there would be a happy ending and both parties would make the case for living happily together ever after.

On the side of the engineers were Ian Firth, of Flint and Neill, and Julia Elton, engineering historian and proprietor of Elton Engineering Books.

Firth has been responsible for a significant number of innovative and architecturally interesting bridges. He introduced most of the key points that would recur throughout the debate. He noted the different involvement of the professions in projects of different scale, with the architect's role diminishing in inverse proportion to the size of the bridge. He was clear that both architects and engineers can be responsible for bad bridges, and that this usually occurs where one party fails to properly challenge their co-designer (River Wear and Glasgowbridge were offered as two examples). He tagged badly run design competitions where the engineering was sidelined or the client badly advised.

Firth identified the cult of the celebrity as one recent phenomenon which worked against engineers receiving proper recognition. Architects tend to be better known, and better at presenting themselves, and therefore are sometimes the only designer credited for a structure, however significant the engineer's role may be.

I was most pleased when he noted that good engineers could design very good bridges without architects involved, citing the work of Schlaich Bergermann und Partner in the present day, and Robert Maillart in the past. However, I was left with the impression that engineers should better aspire to working in collaboration with good architects, and that this was where good design was more likely to arise. Firth noted that the engineering education did not produce design-led, creative types, and that architects could contribute a better-trained imagination.

Elton also focused on education, citing a series of innovative engineers in the past who were perfectly capable of designing excellent structures with only minimal architectural assistance. She decried the lack of awareness amongst engineers about their forebears, suggesting this was why modern-day engineers lacked the confidence and context in which to be creative in their own right. Jean-Rodolphe Peronnet was offered as an example: few in the audience had heard of one of the greatest structural engineers of the 18th century. In contrast, architects understand their history very well, and see themselves as part of a tradition of productive, creative personalities.

I have a lot of sympathy for this point, seeing it in both colleagues and students. I see it as an issue of aspiration: designers need role models to learn from and to set scales of ambition. Many engineers simply fail to understand how great they could be, and along with an education which concentrates on analysis to the almost total exclusion of communication, presentation and creative design, this really does hold them back. I don't personally think we need to develop engineers who are good collaborators with architects - I think we need engineers who can be great designers in their own right, and they will then be successful both alone and in collaboration.

The architectural side of the debate was presented by Jim Eyre, of Wilkinson Eyre, and critic Hugh Pearman. Eyre addressed many of the same points, and presented a few quite ugly examples of what an engineer could produce alone, citing Maillart's Zuoz Bridge as the start of an era of boring engineer-designed bridges. Eyre noted that an architect's training made them far more aware of issues of context, culture, the experiential rather than solely functional side of a bridge, and that engineering training produced people ill-suited to addressing these issues.

He highlighted a period post-Zuoz when the engineer became king, and poor quality visual design resulted: the age of the motorway expansion, where least-cost no longer meant least-material (i.e. elegant), but fastest-to-build, and dull identikit concrete structures resulted.

Eyre also highlighted the key role that the procurement process plays in determining the success of design. Projects are increasingly led from a commercial rather than design perspective, with the contribution that design can make devalued. The increase in contractor-led design, in particular, has led to a focus on value-engineering which often reduces cost while simultaneously diminishing genuine value.

These are fair complaints, but appeared to attack the symptoms rather than the cause. Why do clients not value design? I think that both fee-paying clients and end-users, the public, share a lack of understanding of quality, and hence of value. Put simply, they do not know what a good bridge is, particularly where "good" is defined by engineering attributes. This even extends to visual aspects, where a widespread lack of visual literacy leads to some really spectacularly ugly architect-led designs being lauded as if they were actually good. The internet is full of such designs, and design competitons attract them like super-magnets. Instead, clients and the public often fall back on more straightforward yardsticks such as least-cost, or false signifiers of value, such as celebrity (the "it's Zaha Hadid so it must be good" syndrome).

Pearman did draw attention to the role of the public, who would not normally care about who "owns" bridge design. Architects were simply better at articulating their vision, at explaining design, but even they remain for the most part un-named and unknown to the general public.

I think this issue of "credit" for design is, or should be, a red herring. It seems to exercise many engineers who feel their contribution is often ignored, and while this is true, I think back to the motorway era. Although Jim Eyre suggested this period was the nadir of low-visual-quality, engineer-led design, I think there were also some very creative engineers at work during this period, highly innovative, and visually aware. I've recently posted a series of examples from the Sheffield-to-Leeds and Leeds-to-Manchester motorways on this blog: remarkable, sometimes beautiful structures, where no architect was involved, and where the engineers were not seeking any special recognition, but content to serve the public with humility.

I think it's vital that we train better-rounded engineers, who aspire to emulate the great engineers of the past. It's vital that we train people who can explain and articulate their designs. We should aim to encourage great designers who can transcend their training, from whichever background they come. But the relative roles of different designers only serve as the means towards an end, which is producing great bridges. More effort is require to explain to clients and end-users what "great" actually is, and why it can mean structures without flash, bling or spectacle. Only then can the people who use and pay for our bridges be in a position to "own" bridge design, and allow the designers to slip happily back into the shadows.

Footbridge 2014

I thought I'd try to write a brief summary of Footbridge 2014, held over three days last week at Imperial College in London.

Much of the conference was in the usual format: a series of plenary sessions with twelve keynote presentations (substantially more than Footbridge 2011), accompanied by various themed parallel sessions where the bulk of the papers were presented. These ran in triplicate, so I almost certainly missed more amazing presentations than I saw. If I get time, I'll write here about a few of the particularly interesting presentations. I also barely scratched the surface of the exhibition, which was a shame as there were some interesting products and companies on show.

The conference was very busy: I had time to visit a handful of London bridges the day before the event, but once it started there was so much of interest to see, and so many interesting people to meet, that I never had time to go off-campus.

One of the undoubted highlights was the first night, which featured "Footbridge 10-20", a session where presenters had to speak over only ten slides, each shown for exactly 20 seconds. This is a variant on the PechaKucha presentation format, but half the length, and all the better for it. It really forced speakers to be concise, and if they were boring, well, they were gone quickly and on to the next. The four highlights, for me, were presentations on Thomas Heatherwick's absurd Garden Bridge ("Boon or boondoggle?" - I don't think there's much doubt which it is); "freaky London bridge facts" (one of few presentations not by a bridge designer, builder or client); a comparison of the love of "sexy" (i.e. "iconic") bridges with scopophilia, in its sense as a sexual perversion; and a much-applauded tour of bridges in Hollywood action films, particularly science fiction and fantasy films, discussing how they tend to defy the laws of physics. The last was supported by a paper in the main body of the conference, from which this picture of Asgard's rather improbable Bifrost Bridge is taken.

The second night of the conference was the Gala Dinner, a cruise down the River Thames on a glass walled boat. I know London well, but this was a marvellous night, great company, great sights, and the chance to experience very different characters of the city as daylight faded into night.

The keynote presentations were generally of a very high standard, thought-provoking and wide-ranging. Several showed concern with the philosophy and ethics of design, with Andreas Keil, Marc Mimram, Jürg Conzett, Laurent Ney and Martin Knight all addressing the "why" and "how" of footbridge design as much as the "what".

Keil presented ten objectives for a designer, drawn from the vocabulary of a product designer, and illustrated them with examples from the Schlaich Bergermann and Partners portfolio. My favourite objective was to employ "as little design as possible", illustrated by the Bleichwiesesteg (pictured, right).

Conzett's talk addressed the question of how engineers could draw on "inspiration" without having to compromise their essential character and become "artists". Conzett's inspirations are often historic, such as Brunel's Chepstow Railway Bridge, and he often uses images from the past to provide the key to modern design problems, whether of broad conception or with regard to details. Conzett's timber Murau Bridge (pictured, left), was shown as one structure inspired by the Chepstow span. The approach is like that of a detective, treating historical artefacts as clues to discover a hidden and unsuspected new design solution.

Laurent Ney offered nine design principles, developed in collaboration with Chris Poulissen. These were broadly aligned with Vitruvius's famous three principles of Utilitas, Firmitas and Venustas. Many of Ney and Poulissen's principles are primarily ethical: relating to social integration, minimal waste, recognition of diversity, shared ownership ahead of ego. One principle, "towards an appealing creation narrative", asks for design and construction to embody the culture within which they operate, to create stories with a wider social resonance beyond the specifics of the project.

The conference closed with Martin Knight's talk, "Bridges for places, bridges for people". Like Ney, he was concerned with the role a bridge plays in society beyond the purely functional. The rebuilding of the bridge in Mostar (pictured, right) was offered as an example of a bridge playing both a practical and also a symbolic role, an act of rehabilitation and a site for celebration. He urged designers to "zoom out" and look beyond the bridge itself to its place in a wider context.

I can only scratch the surface of the conference here. Several of the other keynotes were highly informative, and indeed two lectures on footbridge dynamics were both quite amusing, not something often said about this topic. If time permits, I'll pick out a few further papers and projects from the conference, and post here again.

Pontist in print

I'm currently visiting Footbridge 2014, and very pleased to note that the Happy Pontist is now in print for the first time. All the attendees at the event are being provided with a short guide to the pedestrian bridges of London in booklet form, with all the text and images provided from past blog posts here (edited for length!)

If you're attending the conference, and want to read more about any of the bridges featured in the booklet, just google "Happy Pontist" and the name of the bridge, and you should find a link to the relevant post.

Reminder: Footbridge 2014 call for papers

Here's a reminder as the deadline is now approaching:

The ever-popular Footbridge conference has announced a call for papers for its 2014 event. The deadline to submit abstracts is 30th September 2013.

The conference theme is "Footbridges: Past, Present and Future", and papers have been invited addressing the following sub-themes:

1. Historical and heritage structures
2. Dynamic response and structural behaviour
3. Inspirations in footbridge design
4. Planning, design and construction of sustainable footbridges
5. Advances in materials technology for footbridge construction
6. Future directions in footbridge design and construction

IABSE Guidelines for Design Competitions for Bridges

Since starting this blog, one of the most frequent topics I’ve covered has been that of bridge design competitions. This is largely because of the particular opportunity they provide to develop designs for bridges beyond the ordinary. Many of the entries to such contests are, to put it politely, complete rubbish, but is always interesting to see what happens when designers are forced to be unusually creative, when they have to dress to impress.

If you look back through my old posts, you’ll find many commenting on competitions which ended in failure, typically with no bridge being built, and the efforts of the promoter and of the designers wasted. There are also several cases where competitions have been the source of much controversy within the bridge design community, perhaps most notably in the case of Sunderland’s River Wear Bridge (pictured, right). At the height of their popularity (pre-recession), bridge design competitions seemed to fail to deliver with quite some regularity, leading to an entire conference on the issue (IABSE’s 2007 Henderson Colloquium), and the subsequent development by IABSE of guidelines intended to help clients run more successful competitions.

Last week I attended the UK launch seminar for these guidelines, held at the Institution of Structural Engineers in London. This was an attempt to publicise them more widely, particularly to client bodies who might consider going down this procurement route. In the event, the seminar seemed to have very little client attendance, and to be dominated instead by the usual suspects from the bridge design community. I know at least two UK client bodies who are currently planning such contests, but I suspect most are of the view that the recession has put an end to the flamboyance and frivolity with which bridge competitions unfortunately became associated. If true, that would be a shame, as it was clear from the seminar that competitions could still have much to offer.

The seminar was introduced by one of the members of the IABSE competitions working group, Angus Low. As well as explaining much of the background that I’ve described above, he offered the interesting observation that the running of bridge design competitions goes against the natural order of things.

At school, teachers are presented with a fresh cohort of students every year, and teachers become highly practiced at evaluating the efforts of their unskilled juniors. The opposite is true of bridge design competitions: the set of designers which enters them varies little over time, and thus develops considerable understanding of the evaluation process (and the tactics which best respond to it), while client bodies rarely run more than a single competition. Most clients therefore have only limited understanding of the best process to follow.

To put a rather different slant on Low’s idea, you could consider that until now, there was no guidance available to these competition client virgins, but now it is hoped that the IABSE manual will improve their prospects of securing a fertile design relationship and successfully delivering their hoped-for bridge offspring.

The main part of the seminar comprised four presentations. The first, by Brian Duguid, offered a review of previous bridge design contests in the UK, evaluating their success rate and suggesting common factors which united the more productive ones. By Duguid’s estimate, only about 60% of recent UK bridge design competitions actually resulted in a completed bridge. I think that is pretty good: I can certainly look back on periods in my own career where it seemed every design was destined for a dead end, including many where no competition was involved at all.

Duguid presented a series of examples of failed contests, most of which will be familiar to regular readers of this blog: Poole, Glasgow, Stratford, River Douglas, Sheffield and River Soar (pictured, right). I can easily think of others. He noted more which had been successful, at least in terms of getting built: South Quay, Millennium, Gateshead, Poole (again), Stockton-on-Tees, Bootle, Stirling and Glasgow (again). Personally, I would note that not all of these were success stories for their promoters, with several costing their clients far more than was originally budgeted, the Stockton bridge being the worst offender in this regard.

The presentation listed six factors in competition success: funding and political commitment; design parameters; contest rules; consideration of cost; remuneration; and judging. I was particularly struck by Duguid’s comment that many competition promoters ask entrants for a Lamborghini, despite only having the money for a Fiat.

On that theme, he ended with comments on cost and on economic benefit, revisiting ideas previously presented at Footbridge 2011. Design-and-build was suggested as offering good cost certainty, although my own view is that few contractors have the appetite for risk that would allow the more innovative and exciting designs to be developed. The Foryd Harbour bridge (pictured, left) was offered as a counter-argument to this, but I wonder whether the original budget has been held to on that project, given the highly unusual design.

Duguid drew attention to the client’s attempt to calculate the financial value of “iconicity” for the River Wear Bridge, but my reading of their figures is that it was to some extent a spurious exercise, forced to guess widely in the absence of any real evidence.

The second presentation came from Cezary Bednarski, no stranger to this blog. Bednarski has won ten out of the twenty bridge design competitions he has entered, a remarkably high hit rate, but only three of these have been built (Swansea’s Fabian Way, Cardiff’s Roath Basin (pictured, right), and the Inderhavnen Bridge in Copenhagen, the last of which is on site but not yet complete). These statistics are not a good advertisement for the competition as a form of procurement, but I suspect Bednarski’s choice of contests has included more than a reasonable share of what might be called “vanity competitions”, ones where a client thinks they have a good idea, but where the basic foundations of funding and political commitment referred to by Duguid as a key success factor had never been laid.

Such cases might include the Thames Path footbridge at Lechlade (picutred, left) memorably described by its local opponents as “a yuppy tennis racket from hell”; Hadrian’s Bridge in Carlisle; a bridge in Helsinki; the Portsmouth Causeway Bridge; and the Tamar Bridge at Gunnislake. I haven’t covered any of these bridges here before but they include a number of remarkable designs.

Bednarski also highlighted the notorious Krakow bridge competition, won by a concept which had clearly never been graced by so much as the passing touch of a structural engineer. This is not the only case where the competence of a competition’s judging has been drawn into question (the Glasgow scheme already mentioned is another), and it’s depressing to see the inevitable waste of talent and time involved whenever this happens.

The event’s third presentation came from Martin Knight, who had won Helsinki’s Kruunusillat bridge design competition only a few days previously (pictured, right). It remains to be seen whether that scheme will ever be built (with the client having questioned not only the funding but even the types of traffic it may need to carry), although Knight suggested that it formed part of a chicken-and-egg situation where a landmark bridge design was needed to attract developer interest; and only developer interest could result in the provision of funding.

This was the only presentation to really consider the “why” of bridge design competitions – why should clients procure bridges this way, and why should they do so far more often? Knight noted that in Europe, design contests are far more commonly used than in the UK. I think such contests are to some extent a damaged “brand” in Britain, with complaints over their lack of success extending well beyond the niche of bridge construction. Indeed, concern is sufficiently widespread that the day before the IABSE seminar, RIBA announced an investigation into the performance and processes of their in-house competitions office.

Knight opened by asking the audience to close their eyes and think of a bridge, and posited that the bridge they thought of would typically by historic, and possessed of a strong visual identity whether large or small. A readily recognisable view of the bridge, rather than from the bridge, was the most likely visualisation. Unbuilt bridges, and purely engineering concepts (such as calculations and analysis) were unlikely to come to mind, even for the engineers in the audience.

The presentation seemed to be suggesting that these tendencies were a key reason why bridge design competitions are needed. A sense of place is a key feature in much of the best bridge design. Gateshead and Millau (pictured, left, courtesy chericbaker) were cited as examples, while River Wear was offered as the epitome of a desire for place-making being allowed to overpower all other considerations.

The long normal life span of bridges was noted, and this long-lasting legacy was a key reason why appropriate appearance was vitally important. Knight commented that a bridge may only spend 1 or 2% of its lifetime in design and construction, but 98% being seen and used, which seemed to be a request to allow aesthetics the chance to take precedence over structural simplicity or buildability.

The view was that design competitions allow clients the opportunity to see what can really be done to support their agenda when the floodgates of creative teamwork are opened, whether that agenda is economic development, promotion of sustainability, or simply creating publicity. Here, and elsewhere in the seminar, it was noted that competitions can generate ideas that simply would not arise through a single-designer process, however able they may be.

Returning to the question of “why” design competitions, Knight felt that a positive feature of the process was simply that they brought design higher up the project agenda, allowing the benefits of good design to be better recognised.

The final presentation was an interactive walk through the IABSE guidelines themselves, by Naeem Hussain, who had chaired the IABSE competitions working group. I won’t cover this in detail, as the guidelines are after all freely available for anyone to read online. However, I will say that when I first read the guidelines, my thought was that they were too vague to offer the sort of simple process manual that many clients would like.

I now feel differently: they offer sufficient flexibility to address several different problems, and to satisfy widely varying regulatory requirements around the world. It also seems to me that their key purpose is not to tell clients what to do, but to make clients stop and think, a task which seems to be undertaken far too infrequently. Duguid’s presentation had referred repeatedly to the need to set up a competition process that aligns the incentives to designers with the client’s underlying objectives, and perhaps the guidelines might encourage the more careful thinking which could allow this to happen.

Something I would personally suggest, but which was not covered in the seminar, is that competition rules (and any complex procurement process) should be the subject of scenario-testing, where someone role-plays the bidder and seeks to “game” the system, identifying loopholes, perverse incentives and the like.

Several comments from the floor offered the view that the guidelines are not written in appropriate terminology for clients – some of the language seems to suit the perspective of the competitor. I think this is a little unfair (although it’s notable that there were no clients on the IABSE competitions working group), and certainly far less significant than the challenge of making clients aware of their mere existence. I’m aware of at least two bridge design competitions being planned by UK public sector bodies during 2013, and I wonder whether either body has even heard of the guidelines, let alone be following a process which takes on board their content.

I think the first consideration for those who would like to see better bridge design competitions is to repair the “damaged brand”, which can only happen when prominent contests are organised in a way which learns the lessons of past failure, under conditions conducive to a positive outcome. Only then is there a realistic prospect of promoting competitions as a more frequent tool in the design procurement armoury, as they certainly should be.

Footbridge 2014 call for papers

The ever-popular Footbridge conference has announced a call for papers for its 2014 event. The deadline to submit abstracts is 30th September 2013.

The conference theme is "Footbridges: Past, Present and Future", and papers have been invited addressing the following sub-themes:

1. Historical and heritage structures
2. Dynamic response and structural behaviour
3. Inspirations in footbridge design
4. Planning, design and construction of sustainable footbridges
5. Advances in materials technology for footbridge construction
6. Future directions in footbridge design and construction

China bridge tour 2013

Eric Sakowksi, the man behind the highestbridges.com website, is planning another 3-week bridges tour in China, from 3rd to 24th August 2013. Participants will visit 12 of the 13 highest road bridges in the world; the sites of what will be the world's new highest road and rail bridges, currently under construction; the world's two largest rail viaducts; an exceptionally long span footbridge; and many other marvels.

Anyone interested can find out more online. For a taster of what is in store, Eric has recently added some photo albums from his 2012 China bridge tour to his site, and the 2011 China photo album is still there as well. Both are highly recommended.

China Bridges Trip 2012

Here's one for the wealthy (and slightly nutty) of you.

Erik Sakowski, creator of the truly mighty highestbridges.com website, is organising a 3-week tour of bridges along China's Yangtze river. The itinerary will take in 5 of the world's 10 longest suspension bridges, 5 of the world's 10 longest cable-stayed bridges, 5 of the world's 10 longest arch bridges, and many more superlative-loaded treats for the ambitious pontist.

It's a genuine snip at an all-inclusive US$3,950 (excluding air fares to and from Shanghai), and you just need to read the preview to see how amazing it will be. If that's not convincing enough, spend a good hour looking over Eric's mouth-watering photos from his 2011 China bridge trip. Hopefully he won't mind that I've borrowed one of his 2011 photos below to give you a flavour.

Footbridge 2011: papers roundup pt 3

Time to cover two more papers from Footbridge 2011.

There were a number of papers describing bridges which were, at best, odd, and at worst, downright awful. I won't embarrass the authors here, but the most striking examples were all cases where the architect had been let loose on their own and the engineer left to pick up the pieces later*. It was quite a shame to see such highly talented engineers being employed in this way. (*There were also a number of engineer-designed bridges which could have been improved no end by the presence of a sensitive architect!)

One case which left me with more ambiguous feelings was Tim Black's presentation Optimisation in footbridge design. This is a subject I wrote about recently, so I was keen to see the talk. Black is a director of BKK Architects, who had collaborated with RMIT University's Innovative Structures Group to attempt a new approach to tubular footbridges. They took the basic cylindrical form and applied "BESO" (bi-directional evolutionary structural optimisation), a form of topological optimisation, to it, allowing the process to eliminate and rebuild areas of material in response to analytical criteria such as stress and stiffness.

The resulting design is illustrated above. It isn't what the architects expected (they anticipated a more regular perforated tube), and nor is it what an engineer would expect, as it lacks the symmetry you would expect on a simple symmetrical design problem (a simply supported beam). This is because the architects have steered the design process to suit their preconceptions: they have extracted a segment of geometry from the solution which can be repeatedly tiled both around and long the tube, imagining that the correct approach for ease of real-world fabrication is to maximise repetition. Indeed, they have moved on to digital fabrication and precast prototyping.

No engineer would expect an optimised geometry to be tileable, instead, it would be reasonable to expect material to "collect" in the upper and lower walls of the tube according to the bending moment diagram, and to form diagonal elements in the side walls according to the shear force diagram. I like the idea that new structural forms can emerge by "growing" rather than designing a structure, but the demands of construction (ease of fabrication) and the demands of material efficiency (curved and complex elements) are opposed, and it is not easy to imagine how they will be reconciled. A more rigorous and engineer-led approach to optimisation may yet lead to interesting designs, however, and it's good to see architects thinking in this way as well.

Another paper which echoed a subject I've covered here was Markus Hennecke's Pre-stressed granite bridges: a new generation of granite bridges. This was a showcase for Kusser Aicha Ganitwerke's bridges, which achieve exceptionally high span to depth ratios, as much as 50:1. Their bridge at Stevenage (pictured above), installed late last year, manages 49:1. The presentation attracted a keen engineering interest, with many questioners clearly looking to be persuaded on subjects such as local bursting stresses and cable protection. Indeed, bursting stresses may represent a key constraint on the range of designs achievable, as they are resisted solely by the tensile strength of the granite. I wonder whether that couldn't be extended by some form of localised strapping system, however.

Reading back through the conference proceedings, there are several other bridges which would merit attention here, and some very interesting design concepts to store away in my "for future use" folder. However, I want to move on. I'll put together a couple more posts on some of the most interesting bridges shown at the conference, and I also want to cover some of the bridges in Wrocław itself.

Footbridge 2011: papers roundup pt 2

I've had time to jot down a few more comments on the papers presented at Footbridge 2011. Again, this is a highly selective bunch, there were many others which were interesting but which I simply won't have time to cover.

The Arganzuela helicoidal bridge over the Manzanares River, designed by MC2 Engineering Cosultants with Dominique Perrault Architecture, belongs to the increasingly popular genre of helical truss bridges, a genre I have surveyed previously. There are plenty of images online, but I've just chosen one from the conference paper.

It's actually two separate bridges, with a total length of 278m. Each is in the form of a cone, varying in diameter from 6m to 12m, and structurally they are helical trusses, with straight upper and lower chords intersected with spiral diagonals, taking the general form of a through Warren truss. This is pretty much as rational as this helical form ever gets, but as the authors noted, it still imposes significant secondary stresses on the steelwork, requiring substantially more material than would the more conventional solution.

I've included it here because while I have my doubts about the conic geometry (attractive in the widening direction, but visually constricting in the other direction), this is one of the best of its genre. This is largely, I think, because of the cladding treatment, which with its varying densities of mesh, distracts from the structural frame and uses its apparent solidity to create an object with a greater sculptural weight.

I enjoyed Andreas Keil's presentation, Passerelle sur Nanterre - spatial play of forces, on the La Defense footbridge designed jointly by Schlaich Bergermann und Partner and Deitmar Feichtinger Architectes. This is a remarkable 88m long bridge which passes around the perimeter of a curved building, without touching it, and with supports only towards the ends. This is a challenge in itself, but the choice was made to support it on only one edge using the "inverted Fink truss" typology (a system which has only limited resemblance to a genuine Fink truss).

The result is a truly superlative example of high-tech structural engineering. The main vertical support comes from the truss, which is essentially a series of successively cantilevering cable-stays. The number of cables in each bay of the truss are varied according to their order in the cantilever i.e. the number of cables used is proportional to the force to be carried. This system is assisted by a set of ring-cables offset below the deck level, which are cranked back up to deck level at the ends and hence carry a share of the vertical load in a manner similar to an external prestressing tendon. This also reduces the possibility of uplift forces on the bridge's end bearings.

The deck is a hollow steel box, providing some of the much needed torsional stiffness. However, this is far from sufficient on its own, and the lower ring-cables provide the remaining torsional restraint. The vector sum of their forces at each mast position imparts a net inwards force, which, because of its level, acts to counterbalance the torsion resulting from the deck dead and live loads only being supported on one edge. For some reason, the bridge as a whole reminds me of a set of gimbals, as in a gyroscope, possibly because of the way the whole ensemble appears to teeter on only a few pin-point supports.

It's a remarkable bridge.

Another bridge which impressed me was Link 27 - a new footbridge in the west of Vienna, Austria, presented by Rudolf Branstötter. This 38m span bridge was completed on site in September 2010, and was the end result of a student design contest which Branstötter had won. I thought this was an exceptional structure, where the structural form, although unusual, was a carefully thought-through response to the site's very specific constraints.

It spans over both a railway line and the River Wien. The different permissible clearances led to a structural form which has a low level springing on the river bank, and which is supported over the railway from above. One end resembles a concrete arch, while the other is a concrete cantilever, with fixity provided by steel tie-down bars. However, both aspects appear fully integrated. The method of construction was also unusual, with both edge girders precast on site, lying on their side, before being rotated and lifted into place.

Footbridge 2011: papers roundup pt 1

Okay, I thought I would attempt a quick round-up of some of the papers and presentations from Footbridge 2011 which particularly caught my eye. Apologies to anyone whose presentation I saw and found interesting, but have missed out, I only have so much time so will have to be quite selective!

In addition to the three keynotes previously mentioned, I enjoyed Henryk Zobel's Contemporary structural solutions of timber pedestrian bridges, which offered a nice survey of the range of timber designs currently in use. One that struck me as especially attractive was the treetop walkwway in Tharandt, Germany, pictured right (click any image for a larger version). This 118m long curved, stress-laminated timber structure was explained further in its own paper, although I missed the presentation.

There were relatively few other presentations to suggest any acceleration of the use of timber footbridges, although the Margaretengürtel design in Vienna was presented (see my previous post for details), and another presentation addressed some of the reasons why timber bridges remain unpopular in the UK. Client inertia appeared to be the deciding factor, although I know from my own experience as a designer that client concerns over vandalism, fire damage and general durability are often hard to refute. Having said that, at one time, the UK was claimed as home to the longest timber arch footbridge in Europe (the Middlewood Way Bridge near Macclesfield, a 50m span built in 1992), although that claim has certainly now been overtaken by bridges over the River Lora, near Florence (72m span) and in Rimini, Italy (92m span).

One aspect of the conference which I thought was quite unfortunate was the separation of most of the footbridge dynamics papers into a separate strand, which meant that those of us interested in more general design case studies or topics probably saw very little about dynamics at all. The ghettoisation of the dynamics specialists did mean that the entirely non-technical could avoid the subject, but runs the risk of re-opening a gulf between academia and practising engineers which had been temporarily narrowed in the post-Millennium Bridge years.

Nonetheless, some of the dynamics presentations which I did see were quite staggeringly esoteric, and it was tempting to wonder to what extent they were researching areas which were likely to have real practical relevance.

One dynamics paper which clearly was highly relevant, was Aleksandar Pavic's keynote Vertical crowd dynamic action on footbridges: Review of design guidelines and their application. Pavic's paper reviews five current published methods of dealing with this problem (see table, left), provides worked example calculations for a simple structure (itself very useful, given the ambiguities present in some of these documents), and observes that they can lead to very different results, with serious implications both for economy of design and the potential for error.

Two of the guidelines, HIVOSS and SETRA, are available online. It's notable that when Eurocodes 0 and 1 were published, a methodology for dynamic analysis of footbridges was conspicuous by its absence, including the load models which had been expected to appear (and which are given in the 2005 fib document Guidelines for the design of footbridges). Some of this is because the state-of-the-art in this area has been a constantly moving target, but I think it's a shame that Eurocratic deadlines for publication of the Eurocodes were allowed to take precedence over the presentation of standards which would assist rather than confuse designers. For anyone who doesn't follow the footbridge dynamics literature, it must be a real struggle working out how to proceed.

I saw two presentations where weathering steel was treated in very different ways. Martin Knight and Simon Fryer presented Combining engineering and aesthetics: The Town Centre Link, London, which must be one of the largest scale footbridges shown, at some 135m long and 12m wide. It's enormous weathering steel Vierendeel trusses (pictured, right) are detailed to avoid water traps, and are protected against the risk of graffiti by their height above the rail station platforms below, and by the use of full-height glazing on their inner face.

In contrast, Xavier Font discussed the lovely Can Gili Footbridge (pictured left), which I have covered on this blog before. Here, the pedestrians are kept away from direct contact with the rusty weathering steel by an internal guardrail. However, the potential for graffiti clearly exists, and I understand graffiti is now present. The absorbent surface patina on weathering steel makes graffiti hard to clean off, and only a fresh blast cleaning can reliably remove it (in the UK, this is covered by Highways Agency standard BD 7/01). In addition to the cost, I guess that will affect the uniformity of colour of the weathering steel patina, which may be undesirable. I greatly admire the appearance of weathering steel bridges, but as with the timber designs already mentioned, clients may have to adopt a more flexible attitude to the issues of durability and vandalism.

I was also impressed by a couple of weathering steel footbridges presented by Mario Guisasola, but would like to prepare a full post on them some day, as they were easily amongst the best designs presented at the conference.

Okay, that's all I have time for now, I will say more on the conference presentations later.

Footbridge 2011

I spent most of last week in Wrocław, Poland, for the Footbridge 2011 conference. It was a wonderful opportunity to meet old friends and make new ones, and made particularly enjoyable by the generous hospitality of our Polish hosts. The 2011 Footbridge Awards were presented at Wrocław's Town Hall, parts of which dating back to the 13th or 14th century. The gala dinner at the Centennial Hall was also hugely enjoyable, although sadly this didn't take place within the Hall's main building, a spectacular reinforced concrete dome spanning 65m (pictured, courtesy m.by).

The conference featured 162 papers from 38 countries, and I was pleasantly surprised at the generally high quality both of the papers and accompanying presentations. There were seven keynote lectures, of which the first three set the agenda for many of the informal discussions that took place throughout the week.

The first of these was Benchmarking cost and value of landmark footbridges, by Brian Duguid. This took the conference's official theme ("Attractive structures at reasonable costs"), and tackled the question of reasonableness in two ways. First, by presenting a survey of about forty recent landmark bridges which suggested an average cost of about €8k per square metre, or €38k per linear metre. More intriguingly, it asked us to consider what value a landmark pedestrian bridge provides to its local community, and whether we could actually calculate it. I suspect that's a tall order, although perhaps worth pursuing in the current climate (which, at least in the UK, has seen landmark footbridge construction hugely diminished). The presentation nearly managed to make cost estimating sound interesting, which is a tough challenge.

This was followed by Cezary Bednarski's The 'Chained' Bridge: Attractive structures at reasonable cost?, which pursued the theme of "reasonableness" from a very different angle. This talk's contention was that designers have an obligation to avoid waste, and that bridge architects tend to produce designs which are both wasteful and irrational when not restrained by chains, particularly the chains imposed by the requirements of sound structural engineering. A number of examples were given, including a footbridge proposed for Krakow which I have covered here previously (pictured below).

Bednarski's outrage both at its structural impudence and its visual impact on a nearby castle was a rare and welcome case of a head being raised above the parapet, although it proved controversial, with one Polish engineer boldly stating his view that the engineer's job was to help realise the architect's vision, a suggestion which didn't even meet with the approval of many of the architects present. The Poles are clearly treating the Krakow bridge as a serious proposal, with the magazine Mosty ("Bridges") devoting six pages of a recent issue to an explanation of the engineering plans, including various technical and construction sequence diagrams (these make clear, incidentally, that it is a twin-cantilever bridge, not an arch).

Jan Biliszczuk and Wojciech Barcik's keynote presented Footbridges in Poland - the history and present state. This made for interesting viewing following on from open criticism of the Krakow bridge (as well as another landmark footbridge Krakow, already completed). Large parts of the presentation suggested that Poland has yet to catch up with the aesthetic sensibilities that most contemporary footbridge designers aspire to.

The Luk Erosa footbridge, pictured, is one of a number of Polish bridges where bold colour seems to be used to divert attention from an unnecessarily gimmicky structural form and, in many cases, an over-reliance on circular steel tubes. Those tubes are everywhere, the styleless stock-in-trade of dozens of footbridges. The colour at Luk Erosa is pretty inoffensive compared to some of the other examples which were presented. I heard one attendee asking whether it was all an exuberant over-reaction to freedom from communism, but there are other countries in Eastern Europe which don't seem to share this affliction.

In fairness, I heard a lot of criticism of Polish designs, but I saw several footbridges which were sensitive and attractive in appearance. In Wrocław itself, there is a simple glulam timber bridge over the town's old moat (pictured above), which sadly I didn't get a chance to visit, and at Sromowce Nizne, there is a 90m span glulam timber cable-stayed design which is both technically adept and charming (pictured below). [Incidentally, following that last link leads to a collection of the papers from Footbridge 2008, and many other conference proceedings in rather blatant breach of copyright].

There were several other papers that I would like to discuss here, although I am currently snowed under with work, so don't expect anything very quickly. I also visited quite a few bridges in Wrocław, and will post photos and commentary on those, again when time permits.

The next Footbridge conference will be in 2014, and it will have a tough job living up to the hospitality, organisation, and delightful setting which Wrocław provided.