At 10:18 on September 9, 2026, in the No. 2 vertical shaft of the Chongtai Yangtze River Tunnel in Taicang, Jiangsu, the world's largest diameter high-speed rail shield machine pilot slowly rotated the cutterhead and successfully achieved a second launch after completing 41 days of deep maintenance and repair of the entire machine. Just over a month ago, this massive object with a diameter of 15.4 meters successfully crossed the Yangtze River and surfaced after continuous high-intensity excavation of over 10000 meters at the bottom of the river. Now it has started land excavation in a brand new state, heading towards the world record of 13.2 kilometers of single head excavation by a 15 meter ultra large diameter shield machine at full speed.

Crossing the Yangtze River sets a record for underwater tunnels

The Chongtai Yangtze River Tunnel has a total length of 14.25 kilometers and a shield section length of 13.2 kilometers. It adopts a single tunnel double track design with a speed of 350 kilometers per hour, making it the world's fastest underwater tunnel. There are a total of 3 vertical shafts in the shield tunneling section. The section from Well 3 in Chongming District to Well 2 in Taicang City is the Yangtze River water area, with a length of 11.325 kilometers. It was completed on July 30, 2026. The diameter of the Navigation cutterhead is 15.4 meters, the total length is 148 meters, and the total weight is about 4000 tons. It is currently the world's largest diameter high-speed rail shield machine. After continuous excavation of over 10000 meters underwater in the Yangtze River, there are varying degrees of losses in the cutterhead cutting tools, main drive, mud water circulation, hydraulic propulsion and other systems.

41 day deep maintenance and rejuvenation before departing again

The project team collaborated with the shield tunneling manufacturer to conduct a comprehensive physical examination and scientific diagnosis of ten major systems, including cutterhead cutting tools, main drive, shield tail sealing, hydraulic, fluid, and electrical systems. After a system upgrade, the Navigation has achieved a comprehensive recovery of its overall performance, and is now embarking on its journey in its best condition. After the second launch of the No. 2 vertical shaft in Taicang City, a 1.875 kilometer excavation task will be carried out on the land section, crossing areas such as Nanhuan Road, Zhenghe Park, and Longjiang Road. Along the way, the strata are loose and the development of confined water is significant, which puts strict requirements on the control of excavation parameters, suppression of strata disturbance, management of surface subsidence, and protection of buildings along the line. Keywords: Infrastructure News Network, Mechanical Equipment, Shield Machine

Launch a challenge to the world record

The Chongtai Yangtze River Tunnel is constructed by Shanghai State Railway Construction Management Company and China Railway Tunnel Bureau. It is expected to be fully connected by the end of 2026. The excavation process of the Navigation Satellite is a vivid portrayal of China's high-speed rail shield tunneling technology from following to leading. The world record of a 15 meter ultra large diameter shield tunneling machine heading 13.2 kilometers alone is imminent. This high-speed railway artery crossing the Yangtze River will inject new momentum into the high-quality development of the Yangtze River Delta integration. Starting from the water section to the land section, the Navigation Satellite is writing a new chapter in the world of tunnel engineering under the Yangtze River with the hard core strength of Chinese equipment.Editor/Gao Xue