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Tuesday, May 18, 2010

Akashi Kaikyo Bridge

The Akashi Kaikyo Bridge, also known as the Pearl Bridge, has the longest central span of any suspension bridge, at 1,991 metres or 6,532 ft. It is located in Japan and was completed in 1998. The bridge links the city of Kobe on the mainland of Honshu to Iwaya on Awaji Island by crossing the busy Akashi Strait. It carries part of the Honshu Shikoku Highway. The bridge is one of the key links of the Honshu Shikoku Bridge Project, which created three routes across the Inland Sea. The full details of Akashi Kaikyo Bridge is explained in world tour guides below.

Akashi Kaikyo BridgeBefore the Akashi Kaikyo Bridge was built, ferries carried passengers across the Akashi Strait in Japan. This dangerous waterway often experiences severe storms, and in 1955, two ferries sank in the strait during a storm, killing 168 children. The ensuing shock and public outrage convinced the Japanese government to develop plans for a suspension bridge to cross the strait. The original plan called for a mixed railway-road bridge, but when construction on the bridge began in April 1986, the construction was restricted to road only, with six lanes. Actual construction did not begin until May 1986, and the bridge was opened for traffic on April 5, 1998. The Akashi Strait is an international waterway that necessitated the provision of a 1,500-metre or 4,921 ft wide shipping lane.

The bridge has three spans. The central span is 1,991 m or 6,532 ft, and the two other sections are each 960 m or 3,150 ft. The bridge is 3,911 m 12,831 ft long overall. The central span was originally only 1,990 m or 6,529 ft, but the Kobe earthquake on January 17, 1995, moved the two towers sufficiently only the towers had been erected at the time so that it had to be increased by 1 m or 3.3 ft.

Akashi Kaikyo BridgeAkashi Kaikyo Bridge
The bridge was designed with a two hinged stiffening girder system, allowing the structure to withstand winds of 286 kilometres per hour or 178 mph, earthquakes measuring to 8.5 on the Richter scale, and harsh sea currents. The bridge also contains pendulums that are designed to operate at the resonance frequency of the bridge to damp forces. The two main supporting towers rise 298 m or 978 ft above sea level, and the bridge can expand because of heating up to 2 metres or 7 ft over the course of a day. Each anchorage required 350,000 tonnes of concrete. The steel cables have 300,000 kilometres or 190,000 mi of wire each cable is 112 centimetres in diameter and contains 36,830 strands of wire.

The total cost is estimated at ¥500 billion, and is expected to be defrayed by charging commuters a toll to cross the bridge. The toll is ¥2,300 and is used by approximately 23,000 cars/day. Two parks in proximity of the bridge have been built for tourists, one in Maiko including a small museum and one in Asagiri. Both are accessible by the coastal train line.

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