6666 meters! Domestic ultra-large shield machine sets new record for the world's longest underwater highway tunnel construction

A major breakthrough has been reported from the construction site of the Haitai Yangtze River Tunnel: the domestically produced 16.64-meter-class super-large diameter shield machine Jianghai has advanced over 6,666 meters, reaching another key construction milestone.

This tunnel is currently the world's longest underwater highway shield tunnel, also known as the New First Tunnel of the Ten-Thousand-Li Yangtze River.

The entire tunnel is 39.07 km long, with an underwater shield section of 11.185 km. The right-line shield construction section is 9,315 meters long, and Jianghai is responsible for all excavation work in this section.

The equipment was launched in April 2025 and officially entered the Yangtze River waters in September of the same year. It has overcome multiple challenges including complex riverbed strata, ultra-high water pressure, and ultra-long-distance excavation.

Previously, it successfully reached the deepest point of the entire line at 75 meters below the riverbed, setting a record for the deepest underwater excavation by a domestic super-large shield machine.

The construction environment under the river is extremely demanding: soft soil layers, large fluctuations in water pressure, and even slight operational deviations can easily cause stratum settlement. The construction team used six remote controllers to coordinate the equipment, dynamically adjusting excavation parameters throughout the process, controlling tunnel formation error to the millimeter level, ensuring stable and safe operation throughout the riverbed work.

Entering the second half of construction, the tunnel continues to rise overall, requiring the shield machine to maintain a upward excavation posture for an extended period. The changing water and soil pressures further increase the difficulty of control.

The project relies on an intelligent control system to monitor overburden thickness and stratum pressure in real time, dynamically matching excavation speed and grouting standards to minimize disturbance to the riverbed soil.

Jianghai has a total weight of about 5,000 tons and is a completely domestically developed and manufactured shield machine, independent of overseas core technology. Current excavation progress is steadily advancing, getting closer to the goal of completing the right-line breakthrough.

The tunnel is built to a two-way six-lane expressway standard, with a design speed of 100 km/h, and is planned to open to traffic in 2028.

Once opened, the cross-river drive from Haimen, Nantong to Taicang, Suzhou will be reduced from one hour to ten minutes, directly improving the cross-river transportation network in the Yangtze River Delta.