30 August 2017

Australian Bridges: 5. Napoleon Bridge, Sydney

There is plenty of development going on in Sydney, with a prominent site being the Barangaroo area, which sits along the harbour-side north-west of the central business development, and north-east of Darling Harbour.

The southern end of the site has already seen a number of new buildings completed, while the northern end is home to Barangaroo Reserve, a public park with fine views. Between the two, work continues, and will include the Wilkinson Eyre-designed Crown Sydney Hotel.

Barangaroo is separated from the city centre by a number of streets and particularly the elevated Western Distributor Highway. Finding a way through can be like negotiating a concrete maze.

The new Napoleon Bridge, designed by Wilkinson Eyre and Arup, provides one point of connectivity. It's a covered footbridge spanning the busy Sussex Street. It opened in late 2015, and received an ASI Steel Excellence Award in 2016.

The bridge takes its name from adjacent Napoleon Street, which in turn owes its name to the former presence here of Frenchman Francois Girard, who was at various times soldier, teacher, convict, baker, miller, merchant and farmer.

Napoleon Bridge connects at two different levels: at road level to the west and at an elevated level to the east. The level difference is addressed through two escalators and a staircase at the west end.

The span of the bridge over the highway is a slightly odd structure, comprising two steel edge girders connected by chevron-shaped crossbeams, which support a ribbed floor. The edge girders are shaped to resist a maximum bending in the middle, rising visibly above the floor level on either side.

The roof and walls which shelter the walkway are supported on a series of steel portal frames, arranged so that they are perpendicular to the upper surface of the edge girders, rather than vertically. The outline of the portals is crisp and clear.

The ends of the deck girders are quite shallow, and noticeably shallower than the western approach span, which houses the staircase and escalators. There's an awkward piece added to the girder steelwork to visually address the difference in depth of the two edge elements - I don't think it works very well.

The walkway roof continues horizontally above the staircase area, creating a yawning open-ended atrium. I think this is visually effective, a funnel-like portal which announces arrival into the Barangaroo area.

I like the way that it leans out, giving it a visual presence from side alleyways and sense of dynamism. This is a bridge for city-dwellers briskly on the move, not a bridge for flaneurs or ponderers.

One oddity to the roof structure is that it is not fully enclosed, being partially open on the north edge. I'm not sure why this is, but it begs the question as to why this bridge is covered at all.

The answer, I think, can only lie in the Australian obsession with vandalism risks, as most other footbridges above their highways seem to be "adorned" with massive tall anti-vandalism fences. These are normally a hugely disfiguring feature, so it's good to see the issue dealt with in a much more integrated manner here.

Napoleon Bridge sits in a very difficult site, hemmed in by tall buildings and surrounded by street clutter. The temptation for a designer in this setting is to opt entirely for modesty, to avoid adding further to a visually overwhelming environment. I think it's to this bridge's credit that it combines an appropriate degree of restraint with just about the right amount of excess presence.

There are details that can be picked at, such as the awkward structural junction above the support piers, or the disappointingly small extent to which the edge girders are visible above the floor seen from inside the bridge.

Overall, however, it's an appropriate and well-considered design.

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