13 May 2021

Yorkshire Bridges: 33. Western Bank Bridge, Sheffield

Ah, it was good to get out and see an actual bridge again.

I'm not quite sure how I missed this beauty on my previous visits to Sheffield, but never mind.

It was built in 1969 to a design by Ove Arup and Partners and architect Yuzo Mikami. I say "it", but actually there are two bridges here, as shown in the cross-section below.

The bridges carry the steeply sloping A57 Western Bank highway above a pedestrian concourse area in the University of Sheffield campus. They are two-span structures, supported on single bearings below their tetrapodal centre pier, and a pair of bearings at each end.

The bridges were built in a period when the University campus was expanding, and the growth in road traffic had led to the highway being upgraded to a dual carriageway. Up to 10,000 pedestrians were reported to be crossing the road every day before the bridges were introduced.

The reinforced concrete slab decks vary in depth, being 1.2m deep over the central support and 0.84m at the abutments. It's a subtle feature that is not immediately obvious visually due to the large footway cantilevers on the edges of the deck.

Both decks are slightly curved in plan, but as can be seen in the photos, the main bridge deck slabs are straight, with the edge cantilevers varying in width to provide the curve.

From above, there is very little of interest to see. The interest is in the space created underneath the bridge. From below, this is a concrete roof held up on finger supports and providing some shelter from the weather. Glass blocks allow light through the central strip, and recently new lighting has been installed to make this a more attractive space at night.

It's a classic of modernist design, with some similarities to both Kingsgate Footbridge (1963) and Drochaid a' Chaolais Chumhaing (1984). The attraction is in its balance between the monolithic and the skeletal; it's clearly one "thing", like a sculpture, rather than one thing sitting upon another thing, like a conventional two-span road bridge.

The tetrapod supports have an interesting blend of straight and curved geometry: the outer edges form an inverted pyramid, while the inner surfaces of each arm are profiled with the curves of two intersecting hyperbolas. I'm not 100% convinced about the way the arms meet the deck slab and wonder whether a different detail would have been preferable e.g. having the arms project slightly from the side faces of the slab to give more of a "cradling" effect.

The sloping faces in front of the abutments were a conscious design choice, not so much to provide seating as to avoid the "tunnel" effect common to subways with vertical walls. The aim is to integrate the bridge with the adjacent landscaping. I guess the central tetrapods represent a similar visual impulse.

The block seating around the supports is not original. I wonder to what extent it was added to stop drunken students from bashing their heads into the angled support struts?

The concrete appears to have weathered well, and I'm left wondering why such a well-designed bridge isn't a little better known.

The article about the bridge in Arup Journal is well worth reading, including some excellent photographs, design drawings, explanations of the structural analysis, and an unexpected anecdote about students in mini-skirts.

The bridge was rewaterproofed, repaired and had new bearings installed in 2016.

Further information:

08 May 2021

"Link it! Masterpieces of Bridge Design" by Chris van Uffelen

There ought to be a name for this sort of coffee-table architecture book, churned out seemingly by the dozen every month, heavy on the photos, light on text, and filled with an uncritical gosh-gee-whizz approach to its subject. Publishers like Braun have a formula that works, whether the book is about bungalows, home conversions, factory design, corporate gardens, cinema architecture, bamboo architecture, apartment buildings, or, eventually bridges. And all those examples are just a small part of the output from one author, Chris van Uffelen.

Something similar can be found on architectural websites like Dezeen, Archboom, Architizer and Designboom: an ever-growing torrent of archi-gloss, much of it unedited from designer's self-promotional submissions. And make no mistake: it is responsible for a genuine and substantial dumbing down of how "design fans" perceive the built environment, such that even the worst examples of toxic architectural bloat are slurped down like nectar by an audience increasingly addicted to the hyperreal and incapable of rational analysis.

None of which is to say that I find nothing of value in "Link it! Masterpieces of Bridge Design" (Braun Publishing, 2014, 208pp).

This is essentially a sequel to van Uffelen's "Masterpieces: Bridge Architecture + Design" (2009), which I reviewed when it came out. I say "van Uffelen" as if he wrote these books, but they are actually put together by "Editorial Office van Uffelen", who provide publishers with the complete ready-made coffee-table service, even if much of that is simply emailing suitable architects and asking them to submit their marketing material. A disclaimer at the end of the book makes clear that if anything is incorrect, it's the fault of the design firms, not editors or publisher.

So: there's almost nothing in the book that you can't find freely on the internet, and essentially you're paying to fund the marketing efforts of the designers who participate in the publication. And yet ... there are plenty of structures and projects in this book that I was unaware of and intrigued to discover.

"Link It!" includes a smattering of generally remarkable bridges that should be well-known to dedicated pontists: Dublin's Samuel Beckett Bridge; the Millau Viaduct; the Hovenring; the Passerelle Simone-de-Beauvoir; Calgary's Peace Bridge; Jerusalem's Bridge of Strings; etc. I am sure these will be interesting and attractive examples of bridge design for the non-specialist (who are obviously the book's core audience).

Beyond that, there are bridges in China, Austria, Germany, Canada, the Netherlands, Belgium, Denmark, Indonesia which are interesting, in some cases attractive, and often have features that a designer could take inspiration from, or in others spot details to avoid. The quality of the designs is, inevitably, uneven, and each bridge has minimal explanation and certainly nothing in the way of criticism. There are, thankfully, only a handful of complete stinkers amongst those that have actually been built.

I mention that because the book also features a number of unbuilt bridges, generally with little or no detail on when they may be built, or whether they will happen at all. Some clearly won't, like the daft "Bouncing Bridge" proposed in Paris, the deliberately conceptual "Hydraspan" proposed for San Francisco, or the notorious Kazimierz Ludwinow Pedestrian Bridge, in Krakow, Poland.

There are a few designs which I would hope even the more cynical pontist would find appealing. Examples include the Wupperbrucke in Leverkusen, Germany; the timber truss Enniger Bridge in Switzerland; the Phyllis J. Tilley Memorial Footbridge in Texas; and the Green School Millennium Bridge, in Bali. Sadly, it's not hard to think of plenty of other fine bridges that didn't make the cut.

The photographs throughout the book are generally of an excellent quality that show off the subject matter to its best, although they are often the "day-before-opening" images beloved of the architectural press, showing the bridges pristine and generally unsullied even by people or traffic.

In summary, it's best to see this sort of book as a glossy brochure, assembled without any expert curation; but which can still provide some pleasant browsing if not taken too seriously.

02 May 2021

"The Architecture of British Bridges" by Ronald Yee

Where does engineering end and architecture begin? That's the question I was left with after reading Ronald Yee's wide-ranging and informative "The Architecture of British Bridges" (Crowood Press, 2021, 224 pages).

Books on the bridges of Britain tend to fall into three camps: big national surveys; more selective surveys following the author's specific tastes; and studies of niche topics like railway bridges. The new book by specialist bridge architect Ronald Yee surprised me by coming closest to the first camp.

The core of the book is a survey of bridges from around the UK, not comprehensive but very well-chosen. This is bookended by an introductory chapter on the architecture of bridges, and two final chapters on bridge parapets and lighting. There is a useful index but nothing in the way of references or bibliography.

Since much of the first chapter is given over to a layperson's guide to different structural forms, there are actually only three or four pages which specifically tackle the architecture of bridges. I had definitely hoped to read more about this, given the author's own area of expertise. There is a bit of a gap in the market here, as most books and articles about bridge aesthetics are written by engineers, not the architects who now play such a key role in bridge design.

Yee's own architectural approach is one that is very closely aligned to the engineering: he is not one for the outlandish or decorative. His approach to the book's topic is to "show, not tell", allowing the idea of good bridge architecture to emerge through example rather than through a didactic approach.

The message I got from the main part of the book is that Yee sees architecture and engineering as being to some extent complementary and to some extent inseparable. Bridges from all periods are described straightforwardly, with the same attention given to how they work (structurally), as to their place in history, their visual appearance, or their local context. Yes, they may have specific architectural attributes (the description of Chester's Grosvenor Bridge includes its "archivolts of red Peckforton sandston ashlar" and "a frieze and cornice with rectangular modillions", amongst other features; Stirling's Forthside Footbridge's "visual effect is gymnastic and an undeniably spectacular sight"), but these are never anything other than part of the wider story.

This leaves many of the individual bridge entries a little dry, even where the bridges themselves can be seen to have some degree of special interest. In other cases, Yee ventures more of an opinion and I'd certainly like to have seen more of this.

The key strength of the book lies in how well the entries have been curated, and illustrated with generally excellent photographs. Given that Yee is well known for his sketches and drawings, I'd love to have seen more of those - they are few and far between.

I have read many books about bridges in Britain, but I still found plenty here that I was unaware of or which has not been celebrated previously in print. It surveys an excellent range of often exemplary bridges, at all scales great and small.

Presenting the bridges in a gazetteer format, structured by materials and bridge typology, does mean that much is left unsaid about architecture: the way in which bridge design in Britain moved through phases of craft construction, master builders, the era of "scientific" engineering, and the slow and then more rapid rise of architects as the leaders of the design narrative. Yee's book therefore leaves room for some very different treatments of the subject, and hopefully others will step into the breach.