Next to Dunkirk, the gateway linking the towns of Petite-Synthe and Fort Mardyck to Saint Pol sur Mer has been closed to traffic for 5 years. The old bridge, made of reinforced concrete, was built in 1977 and demolished in 2011 for safety reasons due to one of its supports being damaged.
Steel and concrete
To build the new Triangle bridge, the best solution was to opt for a steel-composite structure. The new bridge is composed of a weatherproof concrete floor slab with acoustic insulation. Steel was chosen for the support beams due to its efficiency and for its aesthetic and economical properties. S460M steel is economically beneficial for that type of application. Indeed, the weight of the structure can be reduced with a low price increase, its carbon rate is very low and welding doesn’t require pre-heating.
Since April 2016, the new “Triangle bridge” made with our steel has been opened for traffic. This gateway is a major traffic route for the Dunkirk area as it helps connecting 4 public transport lines which had to be removed during construction. Measuring 116 metres long, the new bridge includes:
Hand in hand collaboration
Steligence® Fabrication Centre in Luxembourg was chosen by the customer Eiffage TP to provide 32 metre-long HEB and HEM 600 beams. Eiffage TP is well-known for realising prestigious civil engineering structures (the Millau Viaduct, the Montparnasse tower, the Channel Tunnel …).
For the assembly, Steligence® Fabrication Centre partnered with the team of Distribution Solutions (DSI) in Yutz, France. This Distribution Solutions team was in contact with the customer’s supervising office, checking compliance with the specifications.
Typology: Composite road bridge
Engineer office: Eiffage TP
Assembly: Distribution Solutions (DSI)
Steel grade: S460M
Section size: HEB and HEM 600
Tonnage: 260 tonnes
Product specialisation: Combination of 2 sections, welded longitudinally