The Akashi Kaikyo Ôhashi
, with a main span of 1,991m, is the longest suspension bridge
in the world: one and a half times as long as the Humber Bridge
or the Golden Gate Bridge
. It opened in 1998 and connects the city of Akashi
, just west of Kobe
, to the neighboring island of Awaji
. The entire bridge is 3.9km long.
The bridge was originally planned by the Japanese National Railways (now JR) in the mid-1950's, as part of a rail link between the islands of Honshu and Shikoku. In 1975, after an exhaustive study, the Japanese government elected to build JR's bridge, the Seto Bridge, over a much shorter span closer to Okayama. Ten years later, the government approved the Akashi Kaikyo project as a freeway bridge, placing it under the control of the Honshu Shikoku Bridge Authority that was then supervising the construction of the Seto Bridge. Construction began in 1988 and took ten years to complete.
Both of the 283m main towers are built on reinforced concrete caissons set underwater, each 80m in diameter. The ground below the Akashi Strait was dredged to a depth of 60m to accommodate the caissons, which together have to support 120,000 tons. Each anchorage is built on reclaimed land using 350,000 tons of concrete. The cables in the bridge contain a total of 300,000 km of wire: each cable is about a meter in diameter and contains nearly 40,000 strands of wire. If that isn't enough engineering to make your mind boggle, consider this: the bridge is strong enough to withstand an earthquake at 8.5 on the Richter scale (and it did, in fact, withstand the Great Hanshin Earthquake while it was under construction).
If you don't have a car, the best way to see the bridge is to get on a westbound train on the Kobe Line from Osaka or Sannomiya, and keep an eye out on the left side of the train, which will pass directly under the bridge. See Japanese engineering at its finest, and make sure you come home through Kansai International Airport.