
The Kita Bisan-Seto and Minami Bisan-Seto Bridges
The , or 'Seto-Ohashi Bridge', is a series of double deck
bridges connecting
Okayama and
Kagawa prefectures in
Japan across a series of five small islands in the
Seto Inland Sea. Built over the period
1978 -
1988, it is one of the three routes of the
Honshū-Shikoku Bridge Project connecting
Honshū and
Shikoku islands. At 13.1 km long, it ranks as the world's longest two-tiered bridge system.
Crossing the bridge takes about 20 minutes by car or train. The ferry crossing before the bridge was built took about an hour. The toll from Kojima (Okayama-ken, Honshu side) to Sakaide (Kagawa-ken, Shikoku side) is ¥3,500, and vice-versa.
The bridges carry two
lanes of highway
traffic in each direction on the upper deck and one
railway track in each direction on the lower deck. The lower deck was designed to accommodate an additional
Shinkansen rail line in each direction.
History
The bridge's history dates back to
1889 when a member of the Prefectural Parliament, , suggested the idea of a Seto Ohashi Bridge.
Okubo Jinnojo was born in a remote village of West
Sanuki. At 23, Jinnojo became a village official. He said: "The 4 provinces of Shikoku are like so many remote islands. If united by roads, they will be much better off, enjoying the benefits of increased transportation and easier communication with each other." He envisioned and worked on several major road projects. He aired his idea for the Bridge in a speech made at the opening ceremony of the first
railway in Shikoku between
Marugame and
Kotohira. While it took a century for his vision to become a reality, another of his ideas, mentioned in a drinking song he composed, was accomplished twenty years sooner:
:''I'll tell you, dear, don't laugh at me,''
:''a hundred years from now, I'll be seeing you ''
:''flying to and from the moon in a space ship.''
:''Its port, let me tell you, dear,''
:''will be that mountaintop over there!''
The bridge idea lay dormant for about sixty years. In
1955, after 171 lives were lost when a ferry wrecked in dense fog off
Takamatsu, a safer crossing was deemed necessary. By
1959 meetings were held to promote building the bridge. Scientists began investigations shortly after, and in
1970 the
Honshū-Shikoku Bridge Construction Authority was inaugurated. Work was postponed by the "oil shock" of
1973. In
1978 the Environment Assessment Report was published and construction got underway. The project took ten years to complete at a cost of $7 billion. 2,000 construction companies and about 13 million workers were employed. Although nets, ropes and other safety measures were employed, the lives of 13 workers were lost during the 10 years of construction. The bridge opened for traffic on
April 10,
1988.
Named bridges

The Shimotsui-Seto Bridge

The Hitsuishijima and Iwakurojima Bridges

The Kita Bisan-Seto and Minami Bisan-Seto Bridges
Six of the eleven bridges are separately named, unlike some other long bridge complexes like the
San Francisco-Oakland Bay Bridge (three bridges and one
tunnel). The other five bridges are
viaducts. The six named bridges are:
★ — A
suspension bridge with a center span of 940 meters which connects Honshū with the island of Hitsuishijima. The 22nd
largest suspension bridge in the world.
★ and — Two identical
cable-stayed bridges with center spans of 420 meters.
★ — A continuous
truss bridge with five spans and a total length of 847 meters.
★ and — Two suspension bridges with a common anchorage between them. With center spans of 990 and 1,118 meters respectively they rank as the 19th and 11th largest suspension bridges.
Trivia
★ A 6.8 meter tall Dodama-jishi guardian was placed in the
Seto Ohashi Memorial Park in
Sakaide.
★ It is designed to withstand violent
typhoons and severe
earthquakes.
★ The roadway of the Bisan-Seto Bridges is 93 m above sea level, above the fog on foggy days.
★ 3,646,000 cubic meters of
concrete and 705,000 tons of
steel were used in construction.
★ It is a sister bridge of the
Golden Gate Bridge.
★ The average height of each tower is 200 meters (658 feet).
★ In the OVA anime
Tenchi Muyo! Ryo-Ohki, the bridge was damaged in a crash landing involving
Ryoko Hakubi and
Ayeka Masaki Jurai. It appeared repaired at the beginning of the third OVA.
★ The
Javanese composer
Gesang Martohartono wrote a song titled ''"Seto Ohashi"'', in the traditional
kroncong style.
See also
★
Akashi-Kaikyo Bridge
★
Kurushima-Kaikyo Bridge
External links
★
Honshū-Shikoku Bridge Authority homepage
★
Seto-Ohasi Bridge at Honshū-Shikoku Bridge Authority