The main tower of the Xihoumen road-rail bridge, located between two islands in Zhoushan City, east China's Zhejiang Province, has commenced underwater construction.

Zhoushan, a city established on the basis of a group of islands, is in the coastal area of the Zhejiang Province in the fringe of Hangzhou Bay.

The 3,118-meter-long bridge, dubbed the world's longest span road–rail bridge, connects Zhoushan City's Jintang and Cezi islands.

Both the railway track and the highway will be built on the same deck. The two railway tracks designed for a top speed of 250 km/h in the middle of the deck and three highway lanes on either side.

With the width of 68 meters, the bridge deck is the widest sea-crossing bridge in the world.

The wide deck contributes to wind resistance and stability of the bridge, said Wang Donghui, chief engineer at China Railway Major Bridge Engineering Group Co., Ltd.

The channel where the bridge is located is a major channel for the nearby port. More than 200 container ships with a load capacity of 30,000 tonnes and bulk carriers pass by every day.

The main part of the bridge is expected to be completed in 2028.

With the high-speed rail travels on the island, the travel time from Hangzhou City, capital of Zhejiang Province, to Zhoushan will be shortened to about one hour.