Viaduct with larger spans, typically lack sufficient horizontal and vertical clearance for large ships. See the Chesapeake Bay Bridge-Tunnel. The Millau Viaduct is a cable-stayed road-bridge that spans the valley of the river Tarn near Millau in southern France. Designed by the French bridge engineer Michel Virlogeux, in collaboration with architect Norman Robert Foster, it is the tallest vehicular bridge in the world, with one pier's summit at 343 metres (1,125 ft)—slightly taller than the Eiffel Tower and only 38 m (125 ft) shorter than the Empire State Building. It was formally dedicated on 14 December 2004 and opened to traffic
Orthotropic deck superstructure allowed bridge launching from both ends of the Millau Viaduct. The Akashi Kaikyō Bridge's orthotropic deck allowed the Japanese to build the longest span at about , or 50% longer than the Golden Gate Bridge. Orthotropic decks permit a very shallow deck depth which reduces the steepness of approach gradients and hence their costs. The form is also widely used on bascule and other moveable bridges where significant savings in the cost of the mechanical elements can be made where a lighter deck is used. The El Ferdan Railway Bridge across the Suez Canal of Egypt is the record