China Mulls Next Super Project: The Longest Undersea Tunnel

Chinese engineers may soon start boring deep beneath the Bohai Sea to build the longest underwater tunnel on earth, embarking on another ambitious super project to increase connectivity in Northeast China.

A plan to construct an undersea tunnel linking the northern port cities of Yantai, Shandong province, and Dalian in Liaoning has been submitted for approval to the National Development and Reform Commission, China’s top economic planner, according to Sun Jun, a prominent tunnel expert and a member of the Chinese Academy of Sciences.

The $43 billion project would be part of the central government’s strategy for enhancing connectivity in the northeast part of the country and encourage regional economic growth. The Bohai Sea Rim region, which covers part of the northern rustbelt area and the upper reaches of the wealthier eastern coast, is an important economic hub and home to 300 million people in more than 150 cities including the capital of Beijing.

The Bohai Sea tunnel would also provide a major component in China’s national transportation network development and a critical part of a 5,700-kilometer highway linking Tongjiang city in the northeast and Sanya in Hainan, Sun said.

Though Dalian and Yantai are only 170 kilometers apart over the Bohai Sea, travel between them takes 12 to 15 hours for a 1,400-kilometer road trip around the bay or more than six hours by ferry. An undersea tunnel would cut the trip to about one hour, Sun said.

The planned tunnel, spanning 125 kilometers beneath the sea, would surpass the combined length of the world’s two longest underwater tunnels — Japan’s Seikan Tunnel and the Channel Tunnel between the U.K. and France.

Construction would cost 300 billion yuan ($43 billion) based on preliminary estimates, more than double the cost of the world's longest sea bridge linking Hong Kong, Zhuhai and Macao, which was completed last year, according to Sun. If construction starts in 2020, the project would be likely to reach completion by 2039, Sun said.

Experts finalized studies on the project after 27 years of discussion. The NDRC review is a key step for major infrastructure projects preceding construction.

The idea of building an undersea tunnel linking Yantai and Dalian was first initiated in 1992 by officials in Yantai. Research teams were set up to study the proposal, but experts disagreed on the timing and construction plan for the project, Sun said.

Now time is running out as economic growth has increased pressure on transportation systems in the region. The existing highway and rail network will fall short of meeting demand for transportation in the next five to seven years, Sun said.

Construction of the planned Bohai sea tunnel will be a massive project taking more than 10 years to complete, given the complicated geological conditions, Sun said. The entire project may consist of bridges spanning islands in the southern part and an undersea tunnel in the north, he said.

This story has been updated to correct the amount of time it takes to drive around the Bohai Sea between Dalian and Yanta. It takes 12 to 15 hours.

Contact reporter Han Wei (weihan@caixin.com)