Construction on the second Jiaozhou Bay undersea tunnel started on Oct 29 in the West Coast New Area of Qingdao, Shandong province.

The tunnel will become the longest undersea highway tunnel in the world, with its main section measuring 15.89 km in length, according to local officials.

More than 8 million cubic meters of earth and stone will be excavated, surpassing Japan's Seikan Tunnel (5.2 million cubic meters) and the Channel Tunnel (4.8 million cubic meters), making it the largest undersea tunnel project in history.

"It is an extremely complex mega project," said Du Yanliang, a member of the Chinese Academy of Engineering.

"It will lead global development of undersea tunnels and be a transportation infrastructure milestone for China."

The second tunnel will be available to trucks and other freight vehicles.

The tunnel is expected to increase economic and trade ties and personnel exchanges between the eastern and western urban areas of Qingdao, according to local officials.

The second Jiaozhou Bay undersea tunnel starts construction on Oct 29 in Qingdao, Shandong province. [Photo provided to chinadaily.com.cn]

The red line marks the location of the second Jiaozhou Bay undersea tunnel in Qingdao. [Photo/dzrb.dzng.com]