17 May 2016

French Bridges: 9. Passerelle du Paillon, Nice

Here's a second bridge from the French city of Nice.

The Passerelle du Paillon is a modern addition to the city, completed in December 2010. It's only a short distance from the railway bridge in my previous post, and it carries pedestrians and cyclists across the wide bed of the river Paillon.

The bridge was designed by noted French architect Alain Spielmann. Coyne et Bellier were the structural engineers, and Eiffage and J. Richard Ducros the contractors.

The budget for the 75m long bridge was 3 million euros, but completion of the bridge was delayed by a year when tenders came in 50% higher than expected.

The main mast is supported on a foundation comprising 30m long 1.2m diameter reinforced concrete piles. Two additional stub columns are located on the foundation, presumably to stabilise the bridge deck against twisting.

The bridge is a symmetrical cable-stayed steel structure, with a 25m tall steel pylon supporting twin decks in an "X" configuration. The 3m wide decks appear to comprise steel box girders on the inner edge, with an outer edge supported from cantilever struts.

Planters have been awkwardly placed at the entrance to each arm of the deck, presumably because the designer didn't consider that a 3m wide space might be attractive to drivers of small cars.

The outer edge of each deck is hidden behind a narrow steel fascia strip, presumably added to provide a clean line and hide the tip of the cantilever supports.

The layout of the bridge is much more attractive than a straight-line bridge would be, but strikes me as over-generous for the bridge's location and likely useage. It's well out of the city centre and alternative walking routes are available at a reasonably close distance, so the layout and dimensions appear excessive. I wonder what had to be omitted from the design to bring tenders back within the original budget?

The twin-span solution, with a single pier in the centre of the riverbed, is appropriate to the location. On the west bank of the river, the footway is narrow, but on the east bank it is wide. An asymmetrical design with an offset pylon could therefore have been feasible, with backstays landing on the east bank.

However, the chosen design minimises intrusive construction works to both banks, and the height of the pylon is perhaps more appropriate to the surroundings than would have been the case for an asymmetric solution.

For the most part, the bridge is well-detailed, without undue fuss. I like it.

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