Viaduc du vallon de Maupré, Steel bridge in Charolles, France

The Viaduc du vallon de Maupré, signed Viaduc de Charolles at its ends, carries the RN 79 over the Maupré valley north of Charolles. Its 325 m deck is a composite steel-concrete structure: a 20 cm prestressed slab sits on V-shaped webs of 8 mm corrugated sheet steel, with a 60 cm steel tube as the lower chord, filled with concrete after assembly. The seven spans reach 53 m, on piers up to 23 m high.

Designed by Michel Duviard and planned by Jacques Combault and Pierre Thivans, the viaduct was built between 1984 and 1987 by Campenon Bernard as part of the Charolles bypass on the Route Centre-Europe Atlantique. It replaced the crossing of the Maupré valley and the D 25 and D 985 roads below. French engineers of the time sought lighter deck girders to cut construction costs, and the Maupré and Sylans viaducts applied solutions first tried on the Pont d'Arbois.

The viaduct's name appears at its ends as "Viaduc de Charolles", while locals and maps also call it pont or viaduc de Maupré, after the valley it crosses. It was designed by Michel Duviard and planned by Jacques Combault and Pierre Thivans, engineers who also worked on the similar Pont d'Arbois and Viaduc de Sylans.

The viaduct carries the RN 79 (RCEA) over the Maupré valley and the D 25 and D 985 roads north of Charolles; it is a road structure with no pedestrian path or designated viewing areas. The deck is 10.75 m wide with two lanes and narrow hard shoulders. To see the piers and the corrugated web panels, follow the roads passing beneath the viaduct in the valley.

The deck hides a single steel tube 60 cm in diameter running along its centre, filled with concrete after assembly. The 8 mm trapezoidal sheets form a V-profile around it, and the 20 cm slab is prestressed transversely. From below, the pale green corrugated underside is the visible sign of this composite design.