This is a 15.1-kilometer bridge and tunnel connecting the cities of Kawasaki in Kanagawa Prefecture and Kisarazu in Chiba Prefecture. It is also called the Trans-Tokyo Bay Highway. About 5 km of the highway, from Kisarazu to an artificial island called Umihotaru, is a bridge above Tokyo Bay. From there it runs for about 10 km as an underwater tunnel to Kawasaki. Work on the highway began in 1987, and it opened to traffic in December 1997. Kanagawa and Chiba Prefectures hope for further expansion in industrial development and tourism through this direct link that bypasses Tokyo.