QINGDAO -- The main shield tunneling work on the world's longest undersea highway tunnel -- the second undersea tunnel of Jiaozhou Bay -- was completed on Tuesday in Qingdao, east China's Shandong Province.

The section for shield-tunneling on the north side of the main tunnel is 3,258 meters long, and the construction team used an ultra-large diameter slurry balance shield machine with a diameter of 15.63 meters for construction.
The team overcame multiple risks, including high water pressure and crossing fault zones, through various innovative methods.
The 17.48-km-long tunnel, with a 9.95-km section beneath the sea, has a designed speed of 80 km/h and will facilitate regional travel.
So far, the tunnel project has been completed by more than 70 percent and is expected to be finished in 2028. Upon completion, it will further accelerate transportation links between Qingdao Urban area and Huangdao District, and optimize the urban spatial structure.