31 March 2015

Bridge competition debris part 27: Nine Elms / Pimlico runners up

Ah, what a wonderful thing is the internet. The organisers of the Nine Elms / Pimlico bridge design competition helpfully made all 74 entries available to the public online and via public exhibitions. Initially, they made one image of each design available, although this represented only 30% of what each competing team was actually judged on. Initially, all the entries were displayed anonymously in the online gallery, so that the public would view each design in a fair manner, however, the organisers have recently revealed precisely who did what, and for most of the entries have now made available the second design board, allowing us to see 60% of what they were marked upon.

It's an impressive field of entrants. I think all the British specialist bridge architects are represented (although none was chosen as a finalist), and there are also big names (in different ways) such as Zaha Hadid, Ney and Partners, Marc Mimram, Dietmar Feichtinger, RFR, Expedition, HOK, Rafael Vinoly, SOM, Snøhetta, Foster and Partners and more.

Ove Arup and Partners participated in a staggering 17 entries, and Buro Happold in 9. No other entrant even comes close. This is not a new strategy in bridge design competitions, but it paid off, with Arup and Happold together providing three out of the four finalists.

Here are the six "runners-up", entries which the jury felt deserved some kind of recognition. Links take you to their detailed design boards, at least for as long as they remain online. I'm not going to cover any of the other entries here, there are just too many, but I will return to this contest one more time to discuss it further.

Wilkinson Eyre Architects Ltd with Aecom, Atelier One and Schlaich Bergermann
For me, this is an extremely disappointing design, particularly given the firms involved. It's hard to see what the merits are of the structural solution, which is essentially a suspension bridge system turned sideways. The shallow profile for the cable hangers means that they are not efficient at suspending the deck, especially given their connection to a main cable rather than directly to a rigid mast.

What's especially surprising about this design is that there are no cycle ramps, only cycle channels within staircases - these are okay for keen adult cyclists going upwards, but useless in the downwards direction and for younger or less fit cyclists. As this is a key challenge for the contest and the site, how on earth did this get judged as a runner-up?

Farshid Moussavi Architecture with Bollinger and Grohmann Ingenieure
I find it hard to express quite how much I dislike this design. It makes no structural sense whatsoever. It's like someone has admired Anish Kapoor's 110m long outdoor sculpture, Temenos, and mistaken it as an idea for a bridge. It's not. The design boards talk about the arches being inclined backwards to counter-balance the cable forces, but they're not shown with sufficient weight, stiffness or inclination for this to be at all feasible.

The ramps also lack credibility, especially at the south end of the bridge where there simply isn't space in reality for the length of ramp illustrated.

Eric Parry Architects Ltd with Richard Deacon AKTII
I think this is a design where the image doesn't do it justice. Any arch solution would be expensive to build and difficult to do so without disruption to river traffic. In the design's favour, pedestrian and cycle traffic are properly segregated. It's one of very few entries which didn't follow the obvious route across the river, instead disgorging its users half-way along a busy footway at the south bank. I think it's pretty mediocre, certainly compared to some of the rejected entries.

Atkins Ltd with Grimshaw Architects
This twin-mast cable-stayed design is mildly reminiscent of the South Quay Footbridge in London's Docklands, at least in its original configuration, with two inclined masts supporting an S-shaped deck. It's a rational solution, with ramp arrangements and engineering which makes sense, although I think the giant glowsticks have a garishness more appropriate to a children's Halloween party than blown up at this scale. But it's not a big sin.

The deck is very wide, 10m, and this requires cable stays on both sides of the deck, which is a less elegant solution than at South Quays.

Coffey Architects with Buro Happold
It looks like a plank, or perhaps a ruler placed temporarily on a walnut-wood architect's model as a placeholder while someone else in the team worked on the actual bridge design. I like the bold concision of this proposal, which would be London's first stress ribbon bridge, and a remarkable feat if ever built. However ... it is supposed to be a bridge which happily accommodates cyclists, and it's hard to see how forcing cyclists up in the air in giant lift towers satisfies that aspect of the project brief. Because a stress ribbon inevitably sags between its supports, the support towers have to be quite tall, and because it requires a very high tension force in its supporting cables, those towers have to be large and heavy, with correspondingly heavy foundations. It's bold, but the jury would have been very brave if they'd made it a finalist.

Ove Arup and Partners Ltd with Studio Egret West
At first glance, I thought this striking design might involve plastic composites, but it turns out this is a proposal for an all stainless steel bridge. Since the jury generally appeared to be looking for sensible, affordable solutions, it's hard not to wonder quite how such an expensive idea made it to the shortlist.

There are some nice features, like a cafe below its southern ramp, and a proposal to build the two halves parallel to the river and then rotate them into their final position. But these have to be set against a bizarre intention to cross-over the cycle and pedestrian routes at midspan, introducing an entirely pointless mid-river pedestrian crossing.

The contest organisers have now released the jury report to competitors, and once I've had time to digest it, I'll return with some final thoughts on this competition.


Anonymous said...

Re Wilkinson Eyre design - Their submission shows alternative ramp solution for the ends of the structure, which I think answers the queries as to cyclist provisions.

The Happy Pontist said...

Yes it does. "Here's our design, which doesn't work, but if you don't like it, we can offer you an alternative which does".

Why not just provide a suitable solution in the main design?

Anonymous said...

Re Wilkinson Eyre design - Don't alternatives seem appropriate for a preliminary stage of a competition in which the final site has not yet been defined? The brief clearly calls for an approach to design rather than a final solution. Furthermore, if stairs and elevators 'don't work' why did the brief favour them over ramps which at the required 1:21 gradient 'would have a large footprint and considerable visual impact'.

All 4 finalists seem to have ignored all river wall requirements, opting to build approach ramps over the river rather than on land. They accommodate cyclists while impacting minimally on the surroundings (until the Thames floods), having their cake and eating it too. Ignoring flood defence seems like a big risk, but for all of them it paid off.

The Happy Pontist said...

I will have more to say on this in the next post, but yes, it was not a competition between designs, and therefore it is reasonably to expect the "winning" designs to show a need for further development. However, there were clearly a number of designs in the reject pile which actually did satisfy the site's constraints. So why prefer those which didn't? I think what's apparent is that the jury panel themselves hadn't deeply thought through the design possibilities, hence the preference for unsatisfactory designs. It is difficult faced with 74 widely different entries to give them all a thorough evaluation, unless you have spent time trying to tackle the same challenges yourself.