Egret Bridge Over River Yoshino: A New Cable Truss Bridge

This paper is concerned with the construction of a link highway crossing over 1.3 km wide River Yoshino at 1.8 km upstream from the sea. Along the right hand side of the river, shallow oxygen-rich tidal flats are extended, where bottom-dwelling creatures, fish, crabs and migratory birds live; while there is a deeper current at the left hand side. The part of the bridge over the tidal flats will be a three-span and single-layer cable-truss system of the length 500m with two towers clamped to the ground and two intermediate vertical piers in the air. The superstructure is rigidly connected with piers and consists of steel I-girders with the sandwich slab of the steel-encased concrete. The piers over the deeper current are designed very thin in the transverse direction of the bridge not to hinder the river current and consist of steel pipe and concrete sheet piles and fill-in soil. Now the bridge is at the phase of detailed design and will be completed in a few years.