On September 29, the whole Dalian Bay undersea tunnel was completed, which is the first cross sea immersed tunnel in northern China. The Dalian Bay subsea tunnel is 5.1 kilometers long and consists of 18 immersed tubes. During the construction, the project team applied a number of technical achievements, such as the full floating leveling process of the gravel bed, the localization of underwater cable sockets, the automatic leveling system of the leveling ship, and the information intelligent management cloud platform for immersed tube installation, to achieve the goal of installing 18 immersed tubes in 20 months. When the Dalian Bay undersea tunnel is opened to traffic, it will add a north-south fast passage for Dalian, which is of great significance for alleviating traffic congestion in the central urban area of Dalian, expanding urban development space, and promoting the integration of the two sides of the Dalian Bay. (This is the scene of Dalian Bay undersea tunnel on September 29.) (This is the construction site of the Dalian Bay undersea tunnel taken on September 29.) (On September 29, workers were working in the Dalian Bay undersea tunnel.) (On September 29, workers were working in the Dalian Bay undersea tunnel.) (On September 29, workers were working in the Dalian Bay undersea tunnel.) (Liu Xinshe)