Yumemai-ohashi was built between Maishima, the artificial island built in the Gulf of Osaka, and Yumeshima Island in the Konohana Ward of Osaka City in 2001. This was the first floating turntable bridge constructed in the world.
The main shipping route for larger ships in the Gulf of Osaka is usually between Sakishima and Yumeshima islands, smaller ships generally navigate between Maishima and Yumeshima Islands (also known as the northern route). Thanks to the technology of the turntable bridge, Yumemai-ohashi can be rotated to allow larger ships to pass through the northern route when the main route is inaccessible due to an accident.
There are many forms of movable bridges. In the case of Yumemai-ohashi, a floating design was chosen because both Maishima and Yumeshima are reclaimed land and this structure is best suited for the soft ground of the man made islands. The floating bridge is rotated using a tugboat allowing large ships to pass. This is the first time this design has been put into use.
The main body of this bridge weighs about 30,000 tons. The bridge is supported by two pontoons (box-shaped structures), which the bridge uses to float. The floating portion is about 410 meters long. The axis point is located on the Maishima side, which allows the bridge to be turned up to 90 degrees. In the case of an accident, several tugboats rotate the main body of the bridge to allow big ships to navigate between Maishima and Yumeshima Islands.