perennial threat of ice (a bridge's columns would have encouraged ice dams which could block the strait). The Tokyo Bay Aqua-Line is a bridge–tunnel combination across Tokyo Bay in Japan. It connects the city of Kawasaki in Kanagawa Prefecture with the city of Kisarazu in Chiba Prefecture. With an overall length of , it includes a bridge and tunnel underneath the bay—which is the longest underwater tunnel for cars in the world. Drawbridges were impractical here because Tokyo Bay is too active a sea lane. The longest crossing on the Yangtze River in China is a tunnel-bridge-bridge complex, consisting of the Shanghai Yangtze River Tunnel, Shanghai Yangtze River Bridge (one of the longest cable-stayed bridges in the world), Chongming–Qidong Yangtze River Bridge and connecting viaducts at the river's mouth in Shanghai. This fixed link carries the G40 Shanghai–Xi'an Expressway from the north bank to the south bank via two islands and is about in total length. See also List of bridge–tunnels Intercontinental and transoceanic fixed links bridge and tunnel (disambiguation) References