Great Seto Bridge

The Great Seto Bridge (瀬戸大橋, Seto Ōhashi?) 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 with railroad connections included. At 13.1 kilometers (8.1 mi), 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 non-discounted toll from Kojima, Kurashiki (Okayama Prefecture on the Honshu side) to Sakaide (Kagawa Prefecture on the Shikoku side) is ¥3,500, and vice-versa.

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 Shinkansen rail line in each direction.