The construction of a 70 km highway linking Turin, Italy, through the Fréjus Tunnel to Lyon, France, required a considerable number of bridges and viaducts through the Susa Valley at the foot of the Alps. In a large section of the highway, the contractor adopted a single structural solution for both bridges and viaducts using box-section precast units assembled by cantilevering. Spans were also standardized: 100 m long in areas that were most difficult to reach and where the piers were up to 92 m high; 60 m in the adjoining area; and 40 m in flat areas. The overall structural design was inspired by the limit states method. This paper describes bridge and viaduct construction in relation to span length and pier dimensions.