Nagisa Bridge, Aomori Prefecture, Japan

The first hybrid prestressed concrete cable-stayed and steel cable-suspended bridge in the world is the Nagisa Bridge, a single span footbridge, constructed over the Nakamura river mouth in Aomori Prefecture, Japan. The bridge comprised 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 bridge elements show slender sections while maintaining a superior aerodynamic stability and esthetic, because a part of the bridge deck is cable-stayed. A hybrid system of cable-stayed and suspension bridge enables engineers to construct prestressed concrete bridges with longer spans and is expected to have an economical advantage compared with ordinary steel suspension bridges. In this paper the design and construction of this new hybrid bridge is reported and discussed.