Bridge competition debris part 3: Sheffield Parkway

This is the third in a series of round-ups of RIBA bridge competition entries, following on from ones for New Islington and Pennington Road.

The Sheffield Parkway footbridge competition attracted 109 entries, but nonetheless I found it very difficult to find many of them online.

This scheme offered a fairly open brief with a relatively flat and unrestricted landscape, with the footway carried over a dual carriageway. Judging from the images below, that's again a license for every furniture designer or frustrated sculpture to try their hand at bridge-as-blob. I know that sculptor Richard Serra was a big admirer of bridge designer Robert Maillart, but here we're seeing bridge designers taking their inspiration from the likes of Serra.

As ever, click the image for a larger version, and the name of the designer for a link to any relevant details on their website.

Winner
Ramboll Whitbybird + Norlund Architects


Also shortlisted
Satellite Architects + Elliott Wood Partnership


URB Architecture + Ove Arup & Partners


Arup Associates


DLG Architects


Not shortlisted
Edgley Design


Leit-werk [PDF]


Juhana Marttinen + Markus Wikar


David Narro Associates + A+J Burridge

"Understanding Bridge Collapses" by Björn Åkesson

"Understanding Bridge Collapses" (ISBN 0-415-43623-6), Taylor & Francis, 2008 [Amazon UK] seems to be a very timely book, published as it is following what seems like a spate of often catastrophic bridge failures.

There are several books available offering case studies of engineering failure: examples include "Why Buildings Fall Down" by Salvadori and Levy; "Design Paradigms" by Henry Petroski; and more structure-specific titles like Peter R Lewis's books "Beautiful Railway Bridge of the Silvery Tay" and "Disaster on the Dee". Most of these are a pleasure to read for engineer and layperson alike: Salvadori and Levy's book is a personal favourite thanks to its clear illustrations and explanations. Although both it and the Petroski book cover plenty of bridge failures between them (Tacoma Narrows, Point Pleasant, Mianus River, Schoharie Creek, Hatchie River, Dee Bridge, Britannia Bridge), I'm not aware of a book until now that has focussed exclusively on bridge-related case studies.

Åkesson, a former lecturer in Sweden, used case studies of failure to help explain complex structural phenomena to students. His aim with "Understanding Bridge Collapses" is to share some 2o examples of bridge failure with practicing engineers, enabling them both to learn from history and also to understand how the history of bridge failure is also a history of increased technical understanding.

The book covers the following collapses dating from 1847 to 2003: Dee, Ashtabula, Tay, Quebec, Hasselt, Sandö, Tacoma Narrows, Peace River, Second Narrows, Kings, Point Pleasant, Fourth Danube, Britannia, Cleddau, West Gate, Rhine, Zeulenroda, Reichsbrücke, Almö and Sgt Aubrey Cosens VC Memorial. In each case, copious technical detail is provided, including detailed formulae, calculations and diagrams describing the failure mechanism and showing why an insufficient factor of safety was present. In this respect, it's a very welcome book because nowhere else is this level of technical detail brought together in one place.

One thing to note is that the book's title is exactly correct; it's about bridge collapses rather than failures more generally. There were several early suspension bridges (e.g. Union Bridge and the Menai Bridge) which suffered terribly due to aerodynamic excitation, but didn't actually fall down (although many of their contemporaries did collapse), and the book also omits examples like the London Millennium Bridge, which suffered a performance failure but again didn't collapse. The latter omission is particularly interesting because the author quotes with approval Sibley and Walker's 30-year cycle of major bridge failures, each of which represented a major turning point in the development of bridge engineering:

• Dee Bridge (1847)
• Tay Bridge (1879)
• Quebec Bridge (1907)
• Tacoma Narrows Bridge (1940)
• Box girder failures (1969-1971)

Åkesson and Petroski both suggest that on the basis of this pattern the time was ripe for a major cable-stayed bridge collapse around the turn of the millennium. Well, of course, that hasn't happened yet, but the Millennium Footbridge fits the 30-year cycle perfectly, providing a classic example of innovative bridge design pushed beyond the boundaries of current knowledge, and leading to much fruitful research following its failure.

Not all of Åkesson's explanations agree with other authors. Taking Stephenson's Dee Bridge, Petroski blames lateral torsional instability, while Åkesson suggests the culprit is localised plastic deformation of a pin-connection detail. I don't feel that this matters: there's plenty to learn even from an incorrect explanation.

One problem with the book is that there are so many specific details that it doesn't really step back and offer a proper overview. There is very little attention given to the non-technical reasons for failure, Pugsley's "engineering climatology of structural accidents".

The biggest flaw, however, is the seemingly complete absence of an editor - Åkesson's English is far from perfect, and seems not to have been edited at all. At times it's just awkward, but at others it's genuinely difficult to understand some of the points being made. For any book of this sort to get to print with this little intervention is frankly baffling, and it's a constant source of irritation as you read through it.

So do the good points outweigh the problems? I'd have to say I found the book so badly marred by the imperfect English that I can't really recommend it. It's unique, and a very interesting read, but I find myself constantly regretting what I paid for it. Caveat emptor!

Bridge competition debris part 2: Leeds-Liverpool Canal

Here's the second roundup of RIBA bridge competition images, following on from those for New Islington. This time it's the Pennington Road Footbridge competition, for a replacement bridge over a canal in Bootle, Liverpool, which gathered 88 entries.

Again, click on the image for a larger version, and on the link for any relevant information at the designer's website.

Themes this time around? I don't think there are any clear ones. The site's geometry was quite restrictive, and anyone who thought seriously about mobility-impaired access will have had to think hard about how to fit in the ramps, but otherwise there was considerable freedom.

There are some covered bridges (which seems fairly pointless given that the approaches are uncovered). One attempt to reuse and redecorate the existing structure. And one or two tall landmarks which tower over the adjacent housing developments or (in the case of Parklife) look to be a cable short of a full spool.

Winner
Softroom / Eckersley O'Callaghan

Also shortlisted

The following were all shortlisted but I've not found any images of their designs online: Arca / Martin Stockley Associates; B&C Associati; Chris Curtis / Elliott Wood Engineers; Julian Hakes Associates / Alan Baxter Engineers; Youssef Ghali.

Not shortlisted

Amenity Space

Architects in Residence

Architecture 2B

Blackburn Fraser + Parklife

Buro Happold + Studio 3

David Miller Architects

Deer Park Alpha

Grid 53

Halsall Lloyd Partnership

TD

xsite Architecture

Yorik

Post edited 13 October 2008

Here's another one:

Juhana Marttinen + Markus Wikar

Bridges news roundup

Trips to Venice end in trips in Venice
Apparently Santiago Calatrava's controversial new Constitution Bridge in Venice is injuring tourists. If that makes you think of a steel-and-glass monster rearing up and lashing out at wide-eyed visitors, Godzilla-style, the truth is sadly more prosaic - inconsistent glass stair treads creating a trip hazard. I especially liked Venice's daft solution:

"We'll intervene with some sort of signalling system for distracted tourists, perhaps with stickers on the ground," Salvatore Vento, Venice's head of public works, told Corriere.

Even Calatrava himself, who is notorious for fighting against proposed alterations to his bridges, has suggested some of the steps could be modified.

Helical bridges are the new black
The Harthill Footbridge was lifted into place over the M8 motorway in Scotland at the beginning of October (albeit late and over-budget). The design is a lattice truss comprising intertwining helical loops. It must be intended to be eyecatching, because it's certainly not structurally optimum. It is glazed inside the truss which will make repainting difficult - there's also no evidence of how the outside of the glass will be cleaned (e.g. a maintenance walkway). It seems to be part of a trend: similar bridges include the nearly identical Greenside Place Link Bridge in Edinburgh; and the Marina Bay Bridge in Singapore (inspired, like the Amgen Bridge in Seattle, by the shape of the DNA double helix).

To infinity and beyond
The iconic North Shore Footbridge, designed by Expedition Engineering, has had its two arches installed (using the same crane as at Harthill, incidentally) and is now named the Infinity Bridge. The bridge occasioned some controversy last year with a war of words between Chris Wise and Stephen Spence (also of River Wear bridge fame) as to who actually came up with the design.

Bridge competition debris part 1: New Islington

I have an ongoing interest in RIBA bridge design competitions, as may be obvious. To round off previous posts, I'm going to offer a series of posts bringing together in one place lots of the competition entries; both the winners and the losers. Noting that there have been several unsuccessful outcomes with the RIBA competition winners (e.g. Stratford and River Wear), I think it's interesting to consider whether the available pool of entries might have led to a different outcome.

Looking through both the successful and the unsuccessful designs for the New Islington footbridge competition, three immediate thoughts come to mind.

One is that despite the competition brief very clearly calling for a "sketch" design, many of the submissions were complex computer visualisations, no doubt with the aim to catch a judge's eye, but representing a level of effort entirely disproportionate to the odds of getting shortlisted.

The second is that the geometrical problem (to link five paths at different levels and in different directions) led to many variations on a small number of basic ideas: the ring and the starfish being the most popular. So: does the client really benefit from so many entries (87)?

The third is the distinct impression that many of the entrants would be better off with a career in furniture design than bridge design; they seem to think (and the judges seem to share this view) that the same principles can apply to both. Most of the entries shown below offer little or no evidence that basic structural concerns have been given even a passing thought. Which, for a bridge, is odd.

I intend to offer the entries without further comment. I'm limited to what I can find online, so I don't know how representative a cross-section of the entries these are. In general, clicking on the image should take you to a higher resolution version; clicking on the entrant's name should take you to any further information on the design available at their website.

Winner
Michael Hadi Associates & Gollifer Langston



Also shortlisted
Gunning Groothuizen Architects


McChesney Architects & Atelier One


Techniker + Glowacka Rennie



Not shortlisted
172architects


David Narro Associates + A+J Burridge


Arup + David Miller Architects


Buro Happold + FoRM Associates


Flower Architects


Hot Architecture


ROEWU Architecture


SMC DTR:UK


The Space Studio


Urban Future Organisation


West Architecture

Working Architecture Group

Added 5 May 2009:
Guy Nordenson Associates

Learning From Bridge Failure

The Institution of Civil Engineers hosted a seminar on "learning from bridge failure" on 24th September. In the wake of the I-35W disaster (pictured) and Montreal overpass collapse, it was felt that perhaps more can be done in the UK to share the lessons of bridge failures, and try and minimise the chance of similar catastrophes occurring elsewhere. The recorded video of the seminar is available along with all the presentations at ICE's lectures website.

While the Montreal failure was reported comprehensively and openly, there is concern that not all reasons for failure are being well-disseminated to bridge owners and maintainers. For example, Dave Parker told the seminar of his experiences as a reporter for New Civil Engineer trying to find out why Palau's Koror-Babeldaob Bridge collapsed in 1996. The real reasons remain unclear to this day.

Several of the seminar presentations addressed the way in which UK bridge authorities have dealt with and are dealing with the risks of bridge failure. Barry Mawson gave a quick run-down of the history of bridge failure in the UK: the failures of four box girders which led to the Merrison Committee; the introduction of a bridge assessment programme dealing with increased highway loads and addressing shortfalls in previous design practice (e.g. understanding of shear prior to the 1970s); the moratorium on post-tensioned bridge construction following the 1985 Ynys-y-Gwas collapse; and ongoing efforts to improve management of sub-standard bridges.

Graham Tilly used a similar range of examples, including the 1967 Silver Bridge eyebar failure (pictured) and 2003 Kinzua Viaduct collapse to identify a recurring theme of inadequate inspections - many bridges which fail have been inspected recently beforehand, but the flaw that leads to collapse is not identified. Partly this is because inspectors concentrate on "serviceability" defects such as surface rust, cracking and spalling, rather than the key non-redundant components which can lead to ultimate collapse. It's also because many defects (as on Montreal's half-joints or Kinzua's anchor bolts) are hidden from normal view.

The implication is that bridge maintainers need to focus on developing new methods of inspecting hidden details and apply them to the most vulnerable details, such as half-joints, buried tie members and hinge-joints, all areas highlighted in a presentation by Neil Louden as being high priorities for the Highways Agency.

Other presentations covered the way in which bridges are overseen nationwide, including the roles of the UK Bridges Board, Bridge Owners Forum and County Surveyors' Society Bridges Group. Richard Fish's view was that with most major bridge owners represented on one or more of these bodies, lessons from failure can be widely disseminated. I'm not so sure about that: there are several bridge owners who never engage with these bodies: privately operated transport networks like many tram schemes; docks and industrial facilities like refineries; and building owners with car park bridges and link footbridges.

The role of SCOSS and its confidential reporting scheme CROSS were addressed, but as a voluntary agency SCOSS has no powers to investigate bridge failures, and its findings are not always widely disseminated. They have issued a briefing note on the Montreal collapse and also plan to report on the recent GE19 bridge slip (already extensively reported by Transport for London). This highlights the difference a proactive and engaged client body can make; generally less disturbed by the prospects of legal action than are consultants and contractors, they may be better placed to obtain and share relevant lessons with others. I think many incidents are better reported independently however, particularly where failures of client management processes need to be highlighted. The Rail Accident Investigation Branch offers a good example of what can be achieved when there is legislative support (they will be issuing their own report on GE19 and it may be interesting to compare it with TfL's).

One of the most provocative presentations came from Jolyon Gill, who noted the paradox that if there are fewer bridge failures, we will learn less and be less able to prevent them in future. This perhaps accords with the idea (presented by Henry Petroski and others) that major bridge failures go in 30-year cycles (roughly corresponding to the time it takes a new generation of bridge engineers to forget the lessons the previous generation had learnt!), with examples including the 3-decade lapse between the Merrison box girder failures, and the (fortunately non-fatal) failure of the Millennium Bridge to perform as desired.

Gill also quoted Alfred Pugsley's phrase that there is an "engineering climatology of structural accidents", where failures relate not only to engineering ignorance and negligence, but also to political, financial and other professional pressures. In this respect, it's unclear whether the prevailing tendency of UK bridge clients to procure on lowest cost may lead to an increased likelihood of error and hence failure (certainly the quality of bridge maintenance inspections procured by local authorities is often less than satisfactory). Personally, I think cost pressures may instead lead to an absolute avoidance of risk in design, with the consequent discouragement of the innovative structures which are most likely to fail.

The lesson of many past bridge failures is that increased risk of failure is an inevitable corollary of innovation. However, the I-35W and Montreal incidents highlight the fact that we are now in an era where bridge engineers spend more time maintaining existing infrastructure than building new structures. This is a world where the evidence is that inspections are not always thorough, proper maintenance is often postponed, and there is insufficient political understanding of the possible consequences to enable work to be well-funded. From the ICE seminar it's clear that bridge engineers understand the lessons of recent bridge collapses. The next question is whether our financial and political mastesr will do likewise.

Calgary: Calatrava or competition? Controversy!

Calgary is on the hunt for two new "iconic" footbridges to cross the Bow River. And Paula Arab at the Calgary Herald has some very interesting thoughts on how they're going about it.

The story (also reported in entertaining manner in the Calgary Sun) is that a faction in the local council would like to appoint Santiago Calatrava to design two new footbridges in Calgary, at a combined capital cost of US$40-50m, and has agreed to spend US$25m to get both designs, and the first of the two bridges built (see much more here, here and here). Robert Remington asks in the Herald why it should cost so much more than the US$4.5m Liberty Bridge in Greenville, South Carolina. The answer of course is that it shouldn't: at about a 150m span, US$10m would be more than ample for a landmark footbridge.

Paula Arab suggest it's a disgrace that Calgary wants to directly appoint Calatrava rather than holding an open competition, one reason being that a contest promotes greater public involvement and attention. She also suggest the competition route is cheaper and more likely to deliver a scheme that meets a fixed budget. Most importantly, it gives local architects and engineers the opportunity to take part.

These are all good reasons, although anyone thinking that design competitions are the best way to deliver a project within budget is clearly unfamiliar with River Wear, Stratford and numerous other examples. One problem any promoter will see with a competition is that it increases risk: you have less control over which design will be chosen (because competitors will expect a fair jury), and over who the designers are.

The latter point would seem to be at the root of Calgary's decision not to hold a competition: they don't just want a fine "iconic" bridge, they want a Calatrava^TM bridge. The brand name is at least as important as the product, it would seem. Certainly there's evidence from a rash of Calatrava proposals elsewhere in North America that few people on that side of the Atlantic have heard of any other bridge designer. To them, "iconic bridge" and "Calatrava bridge" are essentially synonymous.

Arab is on less confident ground elsewhere, suggesting that bridge competitions are good because every architect and engineers learns to design them in college (they don't), and because structurally they are simpler than libraries or courthouses (the opposite is often true). This misses the reality of open bridge competitions which is that a large proportion of entries are from people who have no idea how structures work, and this is readily apparent in what they enter.

Arab also writes:

Bridges are the quintessential proof that form follows function. It's that rule that leads to the birth of such esthetically attractive structures as San Francisco's famed Golden Gate bridge, more so than attempts by architects to draw fancy, but often impractical designs.

Again, this is a naive point of view. Many of the most successful bridge designs are shaped as they are because form follows constructability rather than permanent function, as can be seen in the works of Robert Maillart, Christian Menn and countless others.

Where I would certainly agree is that a competition is preferable to direct appointment; this is on grounds of simple fairness to the market rather than that it will necessarily produce a better result. An open competition is perhaps not the best way to go, however: it wastes vast sums of money which could be more productively spent, much of it generating designs which are not very good. Calgary could instead consider an invitation-only competition, giving star names the chance to compete against both lesser-known but equally talented designers, and even a few wildcards to ensure that fresh or local talent gets its opportunity too.