The immersed tunnel of the Hong Kong-Zhuhai-Macao Bridge is the first deep-water immersed tunnel in the world in the history of the World Island Tunnel Project, which is of epoch-making significance. The design life of the bridge's main structure is as long as 120 years, which means that for more than a century, the core structure of the bridge body, especially the 6.7-kilometer-long immersed tunnel, cannot have the slightest quality problem. The tunnels of the bridge are connected by 33 sections of immersed tubes, each of which is equivalent to a fully loaded Liaoning aircraft carrier. Such a huge immersed tube also has to ensure the strict error limit of less than 0.5 mm, which makes it impossible to have the slightest error in the transportation process. 
engineers specially built a prefabrication factory for immersed pipe sections in Niutou Island, Guishan, not far from the bridge, and used the most advanced assembly line for production.
Measures to ensure the quality of the core structure