China on Thursday started constructing a cross-sea high-speed railway, dubbed the Yong-Zhou Railway, connecting Ningbo and Zhoushan cities in Zhejiang Province, according to the project designer China Railway Siyuan Survey and Design Group (CRS).

Upon completion, the railway will mark some world bests given the construction difficulty. On the total route of just 76.396 km, there will be 36 medium- and large-sized bridges and 17 tunnels. Bridges and tunnels would account for over 90 percent of its total mileage.

The project in the preliminary stage took ten years, according to Hou Bin, project manager of the Yong-Zhou Railway from the CRS.

The railway is designed to span four waterways: Jintang, Xihoumen, Taoyaomen, and Fuchimen, with seven stations and a designed speed of 250 kilometers per hour.  

According to the plan, the project will build a subsea tunnel spanning 16.18 km in the Jintang waterway section. When completed, it will be China's first offshore shielding tunnel and the longest subsea high-speed rail tunnel in the world, with the most complex strata and difficult construction.  

In the Xihoumen waterway section, the project will build a road-rail bridge, which will become the largest of its kind in the world after completion.

Designed by the China Railway Major Bridge Reconnaissance and Design Institute, the bridge has a total length of 2,664 meters, while the main bridge adopts a cable-stayed plus suspension system.

The whole project will take six years to complete.

The Yong-Zhou Railway is part of the goal of constructing a one-hour high-speed railway traffic circle in Zhejiang Province, aimed to accelerate the integration of Zhoushan and Ningbo into the Yangtze River Economic Belt.