China’s domestically developed “Navigator” tunnel boring machine (TBM), the world’s largest in diameter for high-speed rail projects, achieved a critical milestone this week by reaching the central span of the Yangtze River bed during construction of the Chongqing–Chengdu high-speed railway. The 15.4-meter cutterhead machine has advanced 5,660 meters beneath the river, reaching its 2,830th ring segment amid challenging geological conditions.
Equipped with cutting-edge technologies such as intelligent excavation and automated segment assembly, the “Navigator” operates partially autonomously while maintaining precise control—a testament to China’s leadership in mechanized tunneling. Engineers highlighted its real-time geological forecasting systems, which enhance safety and efficiency during deep-water operations.
The under-river tunnel forms a pivotal section of the Shanghai–Chongqing–Chengdu rail corridor, expected to slash travel times and strengthen economic ties across west-central China. Once completed, the route will catalyze regional integration, offering faster cargo transport and passenger connectivity to major urban hubs.
“This breakthrough accelerates our vision for interconnected growth,” said a Chongqing Transportation Bureau representative. The project underscores China’s rapid infrastructure advancement, with high-speed rail networks now spanning over 45,000 kilometers nationwide.
