World’s Largest HSR Shield Machine Crosses Yangtze River
The world’s largest diameter high-speed rail shield machine, “Linghang” (Navigator), successfully crossed under the Yangtze River on July 30, 2026, completing the underwater section of the Chongtai Yangtze River Tunnel, according to Xinhua News Agency. This breakthrough brings China closer to achieving 350 km/h high-speed rail travel beneath one of the world’s mightiest rivers.
The Chongtai Tunnel Project
The Chongtai Yangtze River Tunnel is a critical control project on the Shanghai–Nanjing–Hefei High-Speed Railway, which forms the eastern section of the Shanghai–Chongqing–Chengdu High-Speed Railway. The 14.25-kilometer tunnel connects Shanghai’s Chongming District with Taicang in Jiangsu Province. It is being constructed by China Railway Tunnel Group under the management of Shanghai National Railway Construction Management Co.
Once completed, the tunnel will be the world’s fastest underwater high-speed rail tunnel, designed for trains to cross the Yangtze at 350 km/h without decelerating — a world-first capability.
The “Linghang” Shield Machine
At the heart of this achievement is “Linghang,” a massive tunnel boring machine jointly developed by China Railway Tunnel Group and China Railway Industry. The machine’s cutterhead measures 15.4 meters in diameter — roughly the height of a five-story building — while its total length reaches 148 meters and its weight approximately 4,000 tons.
As ECNS reported earlier this year, the machine is equipped with advanced intelligent technologies including an intelligent excavation system, a high water-pressure sealing system, and a full-process digital twin platform that enables real-time monitoring and early warning capabilities. These features allow “Linghang” to operate with what engineers describe as “independent thinking, intelligent analysis, and autonomous decision-making,” enabling unattended, unmanned operation in high-risk zones.
Engineering Challenges and Solutions
Li Bin, chief engineer of the Chongtai Yangtze River Tunnel Project, explained the three critical requirements for high-speed trains to cross the river at full speed. “When a high-speed train passes through a tunnel, the larger the entrance, the smaller the wind resistance,” Li explained. This necessitated the development of the 15.4-meter-diameter shield machine.
Precision was equally demanding. Li noted that construction control requirements for alignment are extremely high — errors must be controlled at the millimeter level, with no sharp curves or undulations permitted. Adding to the complexity, the constantly evolving riverbed posed a risk of tunnel displacement. “During construction, the exterior of the tunnel was reinforced to increase the rigidity of the straight path and resist changes in riverbed displacement,” Li said.
Construction Milestones
The shield machine began tunneling from Chongming Island on April 29, 2024. By March 2026, it had completed the 11.18-kilometer underwater journey, setting a world record for the longest continuous excavation by a 15-meter-class large-diameter shield machine. The machine achieved a single-day fastest tunneling rate of 28 meters and a single-month fastest rate of 718 meters.
The project also utilized the “Qiminghao” vertical shaft boring machine, with an excavation diameter of 24 meters, which achieved rapid vertical shaft construction to support the tunnel’s ventilation and access infrastructure.
Regional Impact and Connectivity
Once the tunnel becomes operational, it will end the historical isolation of Chongming Island — China’s third-largest island — from the high-speed rail network. Travel time from Chongming via Taicang to Shanghai’s Baoshan Station will be approximately 17 minutes. The broader Shanghai-to-Chengdu high-speed rail journey will take less than 7 hours.
As the China News Service reported, the tunnel serves the strategic goal of integrating the Yangtze River Delta — one of China’s most economically vital regions — by creating a fast transportation corridor connecting the Shanghai, Nanjing, and Hefei metropolitan areas.
National Strategic Context
The Chongtai Tunnel is designated as a national-level “Two Heavy” project and forms part of China’s “Eight Vertical, Eight Horizontal” high-speed railway network. This national plan aims to create a comprehensive high-speed rail grid spanning the entire country, supporting economic integration, regional development, and technological self-sufficiency.
What’s Next
Project teams are now focused on completing the remaining 1.8 kilometers from Shaft #2 to Shaft #1. Full tunnel completion is anticipated by the end of 2026, after which high-speed trains will be able to cross the Yangtze River without slowing down — a transformative achievement for China’s rail infrastructure and a benchmark for tunnel engineering worldwide.