The river section of the Chongtai Yangtze River Tunnel has been completed, with the world's largest diameter high-speed rail tunnel boring machine finishing an unprecedented 10-kilometer "ultra-long run" beneath the riverbed.
China's independently developed world's largest diameter high-speed rail tunnel boring machine, the "Leader" for the Chongtai Yangtze River Tunnel, successfully arrived at the No. 2 shaft on the south bank of the Yangtze River on July 30, traversing the river waters. This marks the completion of the tunnel boring machine section in the river area of the Chongtai Yangtze River Tunnel, setting a new world record for a single continuous excavation of 11.325 kilometers by a 15-meter-class large-diameter tunnel boring machine. It is also the first global instance of a horizontal tunnel boring machine achieving an underground "intersection reception" with a vertical shaft.
The Chongtai Yangtze River Tunnel is a critical control project of the Shanghai-Nanjing section of the Shanghai-Chongqing-Chengdu high-speed rail link, part of the national "Two Priorities" initiative. Connecting Shanghai's Chongming Island with Taicang in Jiangsu Province, the tunnel spans 14.25 kilometers and includes three shafts. The river section tunnel, stretching from the No. 3 shaft on the north bank to the No. 2 shaft on the south bank, covers 11.325 kilometers. With a maximum burial depth of 89 meters below the riverbed, ultra-high water pressure of 0.9 megapascals, and a design speed of 350 kilometers per hour, it is one of China's most demanding high-speed rail river-crossing tunnel projects with the highest construction standards and greatest difficulty. The project is built by Shanghai National Railway Construction Management Company and constructed by China Railway Tunnel Group.
The "Leader" tunnel boring machine achieved unmanned intelligent excavation under full system algorithm control, surpassing 11 kilometers of continuous single-head excavation beneath the Yangtze River for the first time, completing an unprecedented "ultra-long run" under the riverbed. The Yangtze River estuary section features complex geology, described as a "geological museum, hydrological pressure cooker, and ecologically sensitive area." Shanghai National Railway Construction Management Company, in collaboration with China Railway Tunnel Group, adhered to a "risk-first, systematic planning" approach, routinely applying nine intelligent construction technology systems, including intelligent sensing, intelligent prefabrication, intelligent excavation, and intelligent control. This enabled the successful crossing of areas such as the Yangtze River levee, main navigation channel, and the national-level aquatic germplasm resources protection zone for the Chinese sturgeon.
According to the construction schedule, the project team will organize the "Leader" tunnel boring machine's second launch by the end of August this year, with the tunnel expected to be fully completed by the end of 2026. Once operational, the Chongtai Yangtze River Tunnel will significantly reduce travel time between Shanghai and Jiangsu, allowing high-speed trains to cross the river without slowing down for the first time, and ending the era of no high-speed rail access to China's third-largest island, Chongming Island.