Dillinger heavy plate for the bridge “la Palombe” in Bordeaux

The "La Palombe" bridge (in English the wood pigeon) - named in homage to the night train "La palombe bleue" (the blue wood pigeon) which linked the Basque Country to Paris, via Bordeaux - consists of a 20.8 m wide and 180 m long all-metal structure extended by two access ramps of 195 m, on the Amédée Saint-Germain side, and 185 m, on the Armagnac side. Located south of the Bordeaux-Saint-Jean station, it spans 196 m over the "railway river" formed by the bundle of about thirty tracks and thus connects the newly developed Armagnac and Saint-Germain districts. It accommodates areas reserved for soft means of traffic (pedestrians, cyclists), a double lane reserved for public transport and a traffic lane for cars. The pedestrian and cyclist spaces are separated from traffic by a highly visual structural element, for which the bridge is nicknamed “the two eyes open”. Indeed, the wood pigeon is a bird renowned for its exceptional visual acuity.

Combining technical features and aesthetic creation

With its slender silhouette, it looks like a bird spreading its wings and thus truly lives up to its name. It flies over (or emerges from) a rather austere environment and despite its weight (2,200 t), it gives an impression of lightness that it owes essentially to its all-metal, highly refined structure. Thus, its deck is designed as an orthotropic slab in weathering steel, i.e. with improved resistance to atmospheric corrosion. It is topped (surmounted by) with asymmetrical wing-shaped arches. This choice, which is quite rare, led to a very particular operating mode involving a lot of welding work (about 50 km) on the site and the handling of heavy loads with a mobile crane. Indeed, the deck, built in Belgium, was transported to the construction site in around 50 sections by more than 50 exceptional convoys. It was then assembled and welded on site.

For this work of art, Dillinger supplied more than 550 t of weathering heavy plate in the grade S355K2W+N (also known as Dillinger brand steel DIWETEN 355+N) in thicknesses from 12 to 85 mm.