Saint-Cloud Viaduct, Concrete viaduct in Saint-Cloud and Boulogne-Billancourt, France.

The Saint-Cloud Viaduct is a long reinforced concrete bridge that stretches across the Seine River, connecting the districts of Saint-Cloud and Boulogne-Billancourt. Its robust structure carries multiple lanes of traffic on a series of concrete supports that span the river.

Until 1974 the A13 motorway ended at the Saint-Cloud tunnel exit by the Pont de Saint-Cloud. To link it to the Paris ring road, a tender for a concrete box-girder bridge over the Seine was won by Campenon Bernard Construction; on the Boulogne side the approach replaced part of the Rothschild château gardens. Cracks found on 3 June 1978 led to cable strengthening in 1980, and fissures closed the Paris–Vaucresson section from 19 April 2024, reopened fully by 24 June 2024.

The viaduct's arrival erased the riverside guinguettes, small shops and restaurants that once lined Saint-Cloud's centre, which the structure now skirts. Its concrete piers and prefabricated segments, each 2.25 m long and 3.60 m high, are the work of designer Daniel Badani and contractor Campenon Bernard Construction. Look for the two circular signs mounted on a post beneath the deck.

The viaduct carries the A13 motorway and has no pedestrian or cycle path, so it can only be crossed by car; the speed limit has been 70 km/h since the works. It is best viewed from the banks of the Seine in Saint-Cloud or Boulogne-Billancourt. Since April 2024, closures have affected the Paris–Vaucresson section, so check traffic conditions before travelling.

On the Boulogne-Billancourt side, abutments were built ready for a possible doubling of the viaduct that never came. The deck is assembled from precast segments 2.25 m long and 3.60 m high, and the river crossing alone has seven spans, the longest reaching 101.75 m.