Pont de Noirmoutier, Bridge between mainland and Noirmoutier Island, France

Pont de Noirmoutier is a 583-meter prestressed concrete bridge spanning the Fromentine Strait, linking La Barre-de-Monts on the mainland to Barbâtre on Noirmoutier Island. The roadway runs on slender reinforced concrete box girders supported by several piers that stand in the shallow water and allow tidal currents to flow beneath.

The first stone was laid at Fromentine on 12 May 1969, and the bridge opened to traffic on 7 July 1971, built by Dumez and Sacer under the department's financial direction to offer an alternative to the tide-covered Passage du Gois. A toll charged at first led to protests by Noirmoutrin users in 1977, with roadblocks at the entrances and CRS intervention; the toll was abolished on 1 July 1994. Restoration work, including better deck waterproofing, has been carried out since 2017 after a 2016 assessment.

The structure links the mainland to the island and has changed the rhythm of life on both shores, as residents and visitors can now cross at any time. Before it existed, crossing depended on the tides; today cars and cyclists roll across the lanes regardless of the water level.

The crossing is toll-free and open to cars, motorcycles, bicycles, and pedestrians at all hours, regardless of weather or tides. Standard traffic rules apply on the roadway, and the bridge remains passable even during periods of strong coastal wind.

The bridge girders were reinforced with tensioned steel cables that were tightened after construction to prevent cracking. This technique allowed for a more slender design and saved material while maintaining load-bearing capacity.