| The Honshu-Shikoku Bridge Project, consisting of three routes linking two main islands, Honshu and Shikoku, across the Seto Inland Sea, is a big project aimed to form the trunk road and railway network in Japan. The western-most route, the Onomichi-Imabari highway route includes the Tatara Bridge, with a centre span of 890m, the longest cable-stayed bridge in the world and a total length of 1,480m (exceeding the length of France's Pont de Normandie, the previous record-holder, by 34m), and the Kurushima Kaikyo Bridges (three consecutive suspension bridges). Both these bridges carry a four-lane highway, as well as additional lanes for bicycles, motor bikes and pedestrians. The steel towers are 220m high and shaped like an inverted Y after examining the wind resistance, the structural efficiency and aesthetics.
The stay-cables have two-plane multi-fan shape. Many new materials have been used in the Tatara bridge to achieve a structure which is both durable and lightweight, such as high-strength structural steel and high-strength, high-ductility cable wire. The stayed cable consists of a total of 168 cables (under 21 stages), each composed of 151 (for the smallest cables - 110mm �) up to 379 (for the largest cables - 170mm �) galvanised steel wires (� 7mm). Each cable has a maximum tensile force of 941 tonnes/cable and has been made of semi-parallel wire strands consisting of galvanised wires covered with polyethylene tube in shops.
To prevent the turbulence that results from wind blowing on rain water running on the surface of the 460m long cable, the indented surface in the polyethylene cable coating, that breaks-up water rivulets, was added to provide sufficient dumping instead of the ties between cables. Sockets that are resistant enough to fatigue due to bending vibration as well as that of axial force fix the ends of the strands.
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