August 5，The First Large-scale Cross-sea Immersed Tube Tunnel in North China——The last immersed tube of Dalian Bay Submarine Tunnel was successfully installed.。Complete precise installation of 18 carrier-class immersed tubes in 20 months，It has created the fastest installation speed in the history of cross-sea immersed tunnel construction in the world.、A new record for the shortest time。

Dalian Bay Submarine Tunnel is another project with high technical requirements after the Hong Kong-Zhuhai-Macao Bridge in China.、The construction environment is complex、Super project with high environmental protection requirements，It is the first time for China to build a large cross-sea immersed tube tunnel in cold regions.。The total length of the submarine immersed tube section of the project is 3035 meters.，Consisting of 18 sections of immersed tub，Among，The standard pipe section weighs about 60,000 tons.，Equivalent to the displacement of a medium-sized aircraft carrier，The curve radius of the curve section reaches 1050 meters，It has the largest curvature in China.、Immersed tube tunnel in curved section with minimum radius。

After the completion of the tunnel，It will add a new north-south fast passage for Dalian.，To alleviate traffic congestion in the central city of Dalian、It is of great significance to expand urban development space.。