On May 1, the first cross-sea immersed tube tunnel in Northern China, the Dalian Bay Undersea Tunnel and Guangming Road Extension Project, was officially opened to traffic.

The Dalian Bay Undersea Tunnel and Guangming Road Extension Project starts from Renmin Road in Zhongshan District of Dalian City and extends northward through the Dalian Bay sea area by means of an immersed tube tunnel, connecting to the main roads on the north bank and extending to the 201 National Highway. The total length of the main line is about 12.1 kilometers, including the Dalian Bay Undersea Tunnel with a length of about 5.1 kilometers, and the Guangming Road Extension Project with a length of about 7 kilometers. The construction standard of the project is an urban expressway, with a designed speed of 60 kilometers per hour, six lanes in both directions, and a service life of 100 years.

The Dalian Bay Undersea Tunnel is the first cross-sea immersed tube tunnel in the cold regions of Northern China and is also the country’s first domestically designed and constructed flexible segmental immersed tube tunnel. The project team has overcome numerous difficulties, such as complex geological conditions, high construction risks, and multiple technical challenges, by insisting on independent innovation. They successfully solved the century-old durability problem of marine concrete structures in cold regions, and achieved the independent designing and manufacturing of core equipment and technologies in China, such as large ships and underwater cable sockets. For the first time in immersed tube tunnel projects, they applied new structures and technologies such as “incremental launching” final joints, water-penetrating shore structures, and complete floating and leveling of the gravel base, setting a series of “firsts” and “bests” in the history of immersed tube tunnel construction in China and even the world.