23 October 2011

Merseyside Bridges: 6. Paradise Street Bridge, Liverpool

Wilkinson Eyre built their reputation as specialist bridge design architects with a series of spans where the art of structural engineering was allowed to be the star. The architect's skill lay in pushing the engineering outside its normal comfort zone, in establishing a sense of sublime poise, and in ensuring quality of detailing. Paradise Street Bridge, in Liverpool, represents a major departure from that approach, although not the only such example in their portfolio.

Designed in collaboration with Arup, this £2.4m covered footbridge links a multi-storey car park to a John Lewis department store. The span, approximately 60m, is unusually large for such a structure, although certainly not the longest (the Ney & Partners bridge at Esch-sur-Alzette spans further).

Images of the bridge that I had seen before visiting it were oddly disturbing. The bridge's lack of lateral symmetry appeared forced, with little in the way of obvious logic. From above, a better sense can be obtained of how it works. The bridge kinks to either side of a central axis, but is rotationally symmetrical, with glazing offering views in and out in the areas furthest from the main axis.

A similar sense can be obtained from below. It's more ordered than the crumpled-paper architecture of Frank Gehry, it has more in common with the crystalline geometry of Daniel Libeskind, but it's still more than a little uncomfortable in its disdain for rationalism. While you begin to get a sense of how it works structurally (it's a varying section steel box girder supporting a set of clad and glazed frames), it refuses straightfoward comprehension.

It becomes clear that it's a skewed, distorted cousin of Wilkinson Eyre's earlier Bridge of Aspiration, which introduced the basic idea of a disguised box girder supporting a series of continuously varying frames. It's only when you go inside the bridge that it really starts to make any sense, as it's immediately clear that the outlandish geometry is there simply to obfuscate the possibility of a simple linear crossing, where you can see from one end to the other where you are going, and consequently focus on your destination more than on the journey.

At Paradise Street, there is no clear view from end to end, and instead your attention is drawn to the geometry of the enclosed space, and its relationship to the world beyond. The varying angles of the bridge relative to the sunlight allow the already peculiar geometry to project new patterns against itself, varying with time, season, location and orientation.

As a piece of structural engineering, I hate it - if the relationship between engineer and architect was truly collaborative, that's nowhere made visible. As a way to walk between a multi-storey car park and a department store, it's an interesting and unusual experience.

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