Shintotakachiho Bridge

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Shintotakachiho Bridge
Takachiho, Miyazaki, Japan
377 feet high / 115 meters high
469 foot span / 143 meter span


A rare polygonal arch bridge, the Shintotakachiho became the 8th bridge to tower more than 328 feet (100 mtrs) high within Japan’s Takachiho Gorge region. The asymmetrical arch has an unusually high rise of about 164 feet (50 mtrs) making for a steep rib section of 58 degrees where it meets the foundation.

The arch was built outward at the same time as the road deck, eliminating the need for a highline. To prevent the two halves of the arch from falling into the gorge, several cables were attached from the road deck down to the arch within each spandrel panel. The next vertical spandrel support was then built up to deck level and connected to another short span of roadway. The arch rib was built out a little further and the process repeated itself. Once the two sides of the arch were closed in the middle, the temporary cable stays were all removed from inside the spandrel panels.

The Shintotakachiho bridge overlooks two other arch bridges including a steel span some 246 feet (75 mtrs) high and a stone span around 100 feet (30 mtrs) high. Takachiho Gorge has become a region with more high bridges than any other single location in Japan. These include the Takachiho Railway bridge, the Tensho and Aoba concrete arches, the Ryuten, Unkai and Seiun steel arches and the Kamiiwato concrete beam bridge. All 8 bridges are more than 328 feet (100 mtrs) in height. If you have just one day to visit high bridges in Japan, Takachiho gorge is the place to be!

まれに見る、多角辺形アーチ橋の神都高千穂大橋は、高千穂峡谷地域内で、タワーが100m以上の橋の中で八番目となりました。 非対称的なこのアーチには、ほぼ50mのめずらしく高いアーチライズがあり、基礎部分と結合しているところでは58度の急勾配リブセクションを形成しています。

路面デッキと同時にアーチは外側に向けて造られたため、ハイライン(高架線)を使う必要性を排除しました。二つに分かれているアーチが峡谷に落下するのを防ぐために、それぞれのスパンドレルパネル内部を通し7~8本のケーブルは路面デッキより下のアーチにつながれています。そして、次の垂直補強スパンドレルパネルはデッキの位置まで造られ、別の短いスパンの路面につなげられます。 アーチリブはもう少し外側に向けて造られ、この工程は繰り返されます。二つに分かれているアーチが中央で結合されると、一時的に使われたケーブル支柱は全てスパンドレルパネルより外されます。



Image by Japanese Society of Civil Engineers.

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