At 14:00 on May 11, the cutterhead of the "Mawan" shield machine, which will be used for China's largest-diameter underwater shield tunnel, was successfully lifted and lowered to the bottom of the launch shaft. With this, all major components of the "Mawan" shield machine have been lifted and lowered into the shaft!

The Mawan Cross-Sea Passage project starts at the intersection of Mawan Avenue and Yueliangwan Avenue in Nanshan, crosses Qianhai Bay, and ends at the Dachan Bay Port Area in Bao'an District, where it connects with the Dachan Bay toll station of the Yanjiang Expressway and Xixiang Avenue. The route is about 8.05 km long, including an approximately 2 km subsea tunnel section, which will also be Shenzhen's first subsea tunnel. The tunnel has six lanes in both directions and a design speed of 80 km/h.

The Mawan Cross-Sea Passage will use China's largest underwater shield machine to carry out the shield tunneling task for the 2,063-meter subsea tunnel. After assembly, the main components of the shield machine will reach 140 meters in total length, weigh 4,650 tons, and have a thrust of up to 24,600 tons. The cutterhead of the shield machine has a diameter of 15.53 meters and a thickness of 2.8 meters, with a total weight of 640 tons including cutters and lifting tools.

The lifting and lowering of the cutterhead into the shaft is a key step in the lifting and assembly of the entire "Mawan" shield machine, and also the most difficult and risky procedure. To ensure the safe and smooth lifting and lowering of the cutterhead, the project team organized and planned carefully, prepared a special construction plan, and conducted expert review and verification. Before lifting began, workers received safety training and technical briefings. At 6:00 a.m. on May 11, the cutterhead began to be turned over and lowered into the shaft. During the lifting process, a 650-ton gantry crane and a 400-ton crawler crane were used in coordinated operation. After lifting, turning over, static load testing, and horizontal movement and lowering into the shaft, all commanders and workers stayed at their posts, operated according to regulations, coordinated their work, proceeded steadily, and lowered the cutterhead cautiously. After 8 hours, the cutterhead was safely and smoothly lifted and lowered into the shaft. After the cutterhead is positioned and installed in the shaft, subsequent work such as pipeline connection and complete machine commissioning will begin.

As Shenzhen's first large-diameter deep-buried cross-sea tunnel, the Mawan Cross-Sea Passage, once completed, will handle cargo transport for the Nanshan port area and also serve passenger transport links between the Mawan and Chiwan areas and areas such as Dachan Bay, achieving the "separation of passenger and cargo traffic" for Qianhai's external transport. It is of great significance for reducing the impact of port-related traffic on Qianhai's traffic environment, improving the regional road network structure, and supporting the high-end positioning of the Qianhai Free Trade Zone.