The construction of “Seiun Bridge” was completed in December 2004. This bridge is suspended over the Iyo river between the Route 319 and the ground where Yamashiro junior high school stands.
Awarded the first prize from The International Federation for Structural Concrete in 2006 and that was the first prize ever won by Japan under the category of concrete bridges. Other prizes include the Tanaka prize from Japan Society of Civil Engineers and the prize by the Institute for Pre-Stressed Concrete Engineering.
The structure of Seiun Bridge is a type of truss arch bridge called “Self-anchored PC (prestressed concrete) multiple truss bridge”. Among other such bridges with arched under-truss, this is the largest and the first to have the roadway. Such method of construction was adopted here as the site condition along the deep valley was difficult to set up the large-scale heavy machineries. This way of engineering did not require to construct the staging support nor piers. This type of bridge engineering is expected to become future model to enrich the life of people living in the mountainous area.