Seto Ohashi Bridge, Japan
The Great Seto Bridge 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, Kurashiki (Okayama Prefecture on the Honshū 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.
References sources : wikipedia, gavinangel.com