NAGISA BRIDGE, AOMORI PREFECTURE, JAPAN

The Nagisa bridge in Japan is the first hybrid prestressed concrete (PC) cable-stayed and steel cable-suspended bridge in the world. The single-span footbridge was constructed over the Nakamura river. It comprises a combination of prestressed concrete deck and steel deck and a combination of cable-stayed system and suspension system supported by two towers and two anchors. The hybrid system allowed engineers to construct PC bridges with longer spans. Details are given of the design and hybrid bridge features and of the towers and anchorages, decks, cable layouts, joint between the PC and steel decks, and construction process. The bridge is subjected to cold, strong winds and salt attack. A water-cement ratio of under 40% was chosen for the concrete to increase durability. The coatings used to protect the structures from salt attack are described. Details are given of the owner, designer, contractor, costs and service date.