The , also known as Marcus Bridge in Japan was completed in 1998 and is the world's longest suspension bridge (measured by the length of the center span of ). It links the city of Kobe on the mainland of Honshū to Iwaya on Awaji Island by crossing the busy Akashi Strait. It carries the part of the Honshū-Shikoku Highway.
The bridge is one of the key links of the Honshū-Shikoku Bridge Project, which created three routes across the Inland Sea.
Before the Akashi Kaikyō 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
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
. The Akashi Strait is an international waterway
that necessitated the provision of a -wide shipping lane.
The bridge has three spans. The central span is , and the two other sections are each . The bridge is long overall. The central span was originally only , 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 .
The bridge was designed with a two-hinged stiffening girder system, allowing the structure to withstand winds of , 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 above sea level, and the bridge can expand because of heating up to over the course of a day. The cables are in 350,000 tons of concrete and are one meter in diameter.
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 (US$20
.00) 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.