On April 9, excavation officially began on the world's longest underwater highway tunnel at the mouth of the Yangtze River in Haimen, Nantong. The massive "Jianghai" tunnel boring machine(TBM), which has a maximum excavation diameter of 16.64 meters, was launched to begin work on the Haitai Yangtze River Tunnel.

The Haitai Yangtze River Tunnel spans the Yangtze River estuary in Jiangsu Province, connecting Haimen District in Nantong to the north with Taicang City in Suzhou to the south. The entire route stretches 39.07 kilometers and is designed as a six-lane expressway with a speed limit of 100 kilometers per hour. CRCC is responsible for the 9,315-meter shield tunnel section, which will be excavated using the giant self-developed "Jianghai" TBM.

The project faces significant challenges due to the complex geological conditions beneath the Yangtze River. The "Jianghai" TBM will need to perform an extremely long single-direction excavation. Construction is particularly challenging when passing under the river and its embankments, where settlement must be strictly controlled. Additionally, geological surveys of the riverbed have been limited, leaving many unknown variables.

To address these challenges, engineers have enhanced the TBM with several innovative features. They increased the opening rate of the cutter head and installed high-pressure flushing systems and early warning mechanisms to prevent mud buildup. The machine is equipped with retractable cameras that allow operators to monitor the cutter head without entering pressurized chambers, effectively reducing risks and improving efficiency. It also features dual slurry injection to improve efficiency. Meanwhile, DDCI technologies at the joints of tunnel segments are used to improve the tunnel’s structural performance in soft soil environments.

The tunnel will play a pivotal role in promoting regional integration within the Yangtze River Delta and the high-quality development of the Yangtze River Economic Belt.