Pont de la Seudre, Concrete bridge in La Tremblade, France.

The Pont de la Seudre is a concrete bridge about 1 kilometer long connecting La Tremblade with the neighboring municipality of Marennes across the Seudre estuary. The structure spans across a bay filled with oyster farming areas and provides views of the estuary system and surrounding shorelines.

The Pont de la Seudre was built between 1971 and 1972 by the Société Campenon-Bernard to link the Arvert peninsula, the Marennes-Oléron oyster basin and the island of Oléron. Its 1,024-metre deck was launched in 79-metre cantilever sections using temporary prestressing cables and a 112-metre launching girder for the precast segments.

The bridge crosses the Seudre near its mouth, where the Marennes-Oléron oyster basin begins. The name Seudre comes from the river it spans, and the crossing is used daily by oyster farmers and shellfish workers moving between La Tremblade and Marennes. From the deck, the rectangular oyster beds and working boats of the basin are visible below.

The bridge carries the D728E road, linking La Tremblade on the Arvert peninsula with Marennes on the opposite bank of the Seudre near its mouth. Its 13 spans include a navigable passage with about 20 m of clearance above the water, so boats pass beneath while traffic crosses above. The deck is 10.80 m wide.

The deck was built by cantilevering 12 balanced segments of 79 m each, using temporary prestressing cables, and a 112 m launching girder placed the precast voussoirs. The main navigational span leaves 20 m of clearance above the water, letting boats pass beneath the 1,024 m crossing.