The Great Seto Bridge or Seto Ohashi Bridge (瀬戸大橋, Seto Ōhashi)[1][note 1] 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 1978–88, it is one of the three routes of the Honshū–Shikoku Bridge Project connecting Honshū and Shikoku islands and the only one to carry rail traffic. The total length is 13.1 kilometers (8.1 mi), and the longest span, the Minami Bisan-Seto Bridge, is 1,100 m (3,600 ft).
Crossing the bridge takes about 20 minutes by car or train. The ferry crossing before the bridge was built took about an hour.
The bridges carry two lanes of highway traffic in each direction (Seto-Chūō Expressway) on the upper deck and one railway track in each direction (Seto-Ōhashi Line) on the lower deck. The lower deck was designed to accommodate an additional set of Shinkansen tracks for a proposed extension of the Shinkansen to Shikoku.[2]
When in 1889 the first railway in Shikoku was completed between Marugame and Kotohira, a member of the Prefectural Parliament, Jinnojo Ōkubo (大久保諶之丞, Ōkubo Jinnojo, 1849–1891), stated in his speech at the opening ceremony: "The four 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."[citation needed]
While it took a century for this vision of a bridge across the Seto Inland Sea to become reality, another of Ōkubo's ideas, mentioned in a drinking song he composed, was accomplished twenty years sooner:
The bridge idea lay dormant for about sixty years. In 1955, after 171 people died when a ferry wrecked in dense fog off the coast of 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 Honshu-Shikoku Bridge Construction Authority was inaugurated. However, work was postponed for five years by the "oil shock" of 1973; once the Environment Assessment Report was published in 1978, construction got underway. The ferry disaster also led to the creation of the Akashi Kaikyō Bridge.
The project took ten years to complete at a cost of US$7 billion; 3.646 million cubic meters (128.8 million cubic feet) of concrete and 705,000 tons of steel were used in construction.[citation needed] Although nets, ropes and other safety measures were employed, the lives of 13 workers were lost during the 10 years of construction.[citation needed] The bridge opened to road and rail traffic on April 10, 1988.
Constituent bridges
Views from outside and riding on the Great Seto Bridge, 2017Shimotsui-Seto BridgeHitsuishijima Bridge (far) and Iwakurojima Bridge (near)The Kita Bisan-Seto Bridge seen from Yoshima IslandThe Minami Bisan-Seto Bridge (near) and the Kita Bisan-Seto Bridge (far)Panoramic View from North side
Six of the eleven bridges are separately named, unlike some other long bridge complexes such as the San Francisco–Oakland Bay Bridge. The other five bridges are viaducts. The six named bridges from north to south are listed below.
The Iwakurojima Bridge (34°24′06.3″N133°48′33″E / 34.401750°N 133.80917°E / 34.401750; 133.80917 岩黒島橋, Iwakurojima-kyō) is a double-decked cable-stayed bridge with a center span of 420 meters (1,380 ft) and a total length of 790 meters (2,590 ft). It is immediately south of the identical Hitsuishijima Bridge.
The Kita Bisan-Seto Bridge (34°23′43.5″N133°49′13.7″E / 34.395417°N 133.820472°E / 34.395417; 133.820472 北備讃瀬戸大橋, Kita Bisan Seto Ō-hashi) is a double-decked suspension bridge with two sections linked by a common anchorage between them. The center span is 990 meters (3,248 ft) and the total length is 1,538 m (5,046 ft). It is the 19th largest suspension bridge in the world. The nearly identical Minami Bisan Seto Bridge is located immediately to the south.
Minami Bisan-Seto Bridge
The Minami Bisan-Seto Bridge (34°21′51″N133°49′31″E / 34.36417°N 133.82528°E / 34.36417; 133.82528 南備讃瀬戸大橋, Minami Bisan Seto Ō-hashi) is a double-decked suspension bridge with a center span of 1,100 meters (3,609 ft) and a total length of 1,648 m (5,407 ft). It is the 13th longest suspension bridge span in the world. It is the southernmost part of the Great Seto Bridge. The roadway of the bridge is 93 meters (305 ft) above sea level.[citation needed]
Seto-Chūō Expressway (upper)
