World's first compound bridge, winner of the Tanaka Award

Naganohara Town Fudo Ohashi Bridge Project

The 590-meter-long Fudo Ohashi Bridge spans Lake Yamba-Agatsuma in Naganohara Town. When construction began in March 2004, it was the world’s first PC compound truss extradosed bridge.

　

In 2009, Prime Minister Yukio Hatoyama’s Cabinet announced that the construction of the Yamba Dam would be halted, and it was portrayed by the mass media as nothing more than a symbolic facility. However, construction of the bridge, which was intended to be a substitute road as part of the Yamba Dam Project, went ahead as planned. Not only did Gunma Prefecture indicate that it would continue the project, but the national government also announced that it would continue the project as part of a Livelihood Reconstruction Project, after considering the results of a resident attitude survey conducted in 2010. CTI Engineering was in charge of the design at this time.

　

The name of the bridge during its construction was the “Lake No. 2 Bridge,” but it was subsequently named the Fudo Ohashi Bridge in 2010, after the nearby famous Fudo Falls. The project was scheduled to be completed in 2011, but it was postponed due to the Great East Japan Earthquake that occurred in March of the same year.

　

The Fudo Ohashi Bridge was awarded the 2010 Tanaka Award, presented by the Japan Society of Civil Engineers, for its significant contribution to the development of composite structure technology in bridge construction. The bridge integrates the structural technology of PC compound truss bridges, which are characterized by their light weight and great appearance, and extradosed bridges, which reduce the use of materials and enable cost reductions. Incidentally, the fusion of PC compound truss and extradosed bridge technologies has resulted in the smallest girder height (6 meters) and the longest span (155 meters) of any PC compound truss bridge in Japan.