Tokunoyamahattoku Bridge
Tokunoyamahattoku Bridge
JapaneseName
Fujihashi, Gifu, Japan
480 feet high / 146 meters high
722 foot span / 220 meter span
2006
Completed in 2006, the Tokunoyama Hattoku bridge is the highest reservoir bridge in Japan and has one of the longest extradosed bridge spans in the world at 722 feet (220 mtrs). Constructed during the same time period as the new Tokuyama Dam, the 480 foot (146 mtr) high structure carries a local prefectural road across the Ibigawa river. The original road along the bank of the river is now hidden under hundreds of feet of water. Also submerged beneath the waters of this huge bathtub are two of Japan’s highest bridge piers at 328 feet (100 mtrs). The graceful and stylish span could have enjoyed some fame as Japan’s highest bridge but was beaten to the punch by the Kokonoe "Yume" Otsurihashi footbridge which also opened in 2006. Both bridges were surpassed in 2009 by the 590 foot (180 mtr) high Hiroshima Airport bridge.
It would only seem logical that Japan would have the highest extradosed bridge in the world. The Japanese built their first one in 1993 and now have more than 100 examples - more than every other country in the world combined. Extradosed bridges are a cross between a concrete beam bridge and a cable stayed bridge. Unlike a cable stayed bridge where the stays are spaced evenly across the entire deck from tower to tower, the center third of an extradosed bridge is usually devoid of cables as is the immediate area on either side of the main towers where there is always an open “window”. By relying much more on the strength of the thicker, prestressed concrete beam span below the roadway, extradosed bridges can have much shorter towers with fewer cables. Extradosed bridges are not suitable for long spans and they have been built primarily as a prettier alternative to the dull look of a pure beam bridge.
On Tokunoyama, the center of the box girder is 11.5 feet (3.5 mtrs) deep - about normal for a beam bridge of that length. The thickness over the piers, however, is 21 feet (6.5 mtrs) deep - about half the 40 foot (12 mtr) depth a normal prestressed concrete beam span would have been. The extradosed cable towers rise just 74 feet (22.5 mtrs) above the roadway, half the height of a cable stayed tower. Designed by Oriental Consultants, the Tokunoyama bridge was constructed by Oriental Shiraishi, Kawada Construction and Showa Concrete JV.
Tokunoyamahattoku Lake and Dam
