Yangtze River high-speed rail tunnel completed after record underwater TBM drive

China has reached a major tunnelling milestone with the completion of the underwater section of the Chongming–Taicang Yangtze River tunnel, a key component of the Shanghai–Chongqing–Chengdu high-speed railway, according to state media and industry reports. The project represents a significant development in large-scale underground infrastructure for high-speed rail.

The tunnel boring machine (TBM) “Linghang” completed an approximately 11 km underwater drive after nearly two years of excavation, forming the central section of the 14 km-long tunnel. With a cutterhead diameter of about 15.4 m, the slurry shield machine carried out one of the largest-diameter drives of its kind for a high-speed railway project.

The tunnel reaches depths of up to around 90 m beneath the Yangtze River, requiring careful control of excavation conditions, including face pressure, alignment, and ground stability.

Underwater rail tunnels present complex engineering conditions, including high external water pressure and variable ground characteristics. For high-speed rail applications, maintaining alignment accuracy and structural consistency is essential to support safe and efficient train operations.

The “Linghang” TBM was equipped with automated and monitoring systems designed to manage excavation parameters in real time, including pressure control and machine positioning. These systems are commonly used in slurry shield tunnelling to support stable excavation under challenging ground and water conditions.

The project also reflects the increasing use of automation and data-driven control in modern tunnelling operations, particularly for long-distance and technically demanding drives.

The Yangtze River crossing forms part of a broader national high-speed rail corridor aimed at improving connectivity between eastern and western China. Once completed, the line is expected to enhance transport capacity and reduce travel times across key regions.