China has reportedly reached a major infrastructure milestone with the completion of the under-river section of the Chongtai Yangtze River Tunnel. Global Times reported that the development was achieved using “Linghang” (Navigator), which is the world’s largest-diameter high-speed railway shield tunneling machine. Crews relied on Linghang, an independently developed mega shield machine that features the world’s largest diameter for its class. Operating continuously beneath complex sub-river geology of riverbed silt and sand, the shield machine operated without intermediate access shafts. Equipped with digital-twin smart controls and advanced geological forecasting systems, Navigator established a global benchmark for long-distance, large-diameter shield tunneling.