Published : 15/05/2026
At a depth of 89 metres below the water's surface at the mouth of the Yangtze River, high-speed trains will travel through the tunnel at 350 km/h. This will be the actual future of the Chong-Tai Yangtze River Tunnel.
The Chong-Tai Yangtze River Tunnel is not only a major project of China's '15th Five-Year Plan' but is also the world's first river-crossing tunnel that allows high speed rail to pass through without decelerating and has the highest speed.
High-speed railway crosses the Yangtze River without decelerating
The Chong-Tai Yangtze River Tunnel is located at the mouth of the Yangtze River, connecting Chongming District in Shanghai (north bank) and Taicang City in Jiangsu Province (south bank).
After completion, it will achieve the feat of high-speed trains crossing the Yangtze River without decelerating, and the travel time from Nantong to Shanghai will also be halved, with the fastest journey taking approximately 40 minutes.
At the same time, it will also rewrite the history of Chongming Island having no high-speed railway, enabling the journey from Chongming to Shanghai Baoshan Station to take only 17 minutes, further reducing the time and space distances within the Yangtze River Delta city cluster.
With a total length of 14.25 kilometres, the tunnel holds several national and even world records. It is the deepest tunnel under the Yangtze River (with its deepest point 89 metres below the water surface) and has the world's longest single-heading excavation distance for a high-speed railway shield tunnel.
It is not only the highest-speed river-crossing tunnel (with a design speed of 350 km/h), but also the world's first river-crossing tunnel that allows for travel without deceleration.
Read more: The world's longest expressway tunnel: China's Tianshan Shengli Tunnel
Why choose a tunnel instead of a bridge?
Today, there are more than 200 bridges already built or under construction over the Yangtze River, but only a dozen or so tunnels. So why was a tunnel, rather than the more common bridge, chosen here at the mouth of the river?
Firstly, since a tunnel passes under the riverbed, it requires no bridge piers, so it does not occupy the golden shipping channel for vessels at the mouth of the Yangtze River, nor does it damage the riverbed.
Secondly, a tunnel helps avoid the impact of adverse weather on the river's surface, such as strong winds and torrential rain, on the operation of high-speed trains.
Inside the tunnel, high-speed trains can travel at the full speed of 350 km/h, whereas speed limits are usually required on large-span bridges.
Thirdly, this area of water is a national-level aquatic germplasm resources conservation area for the Yangtze coilia.
Construction of the tunnel within the rock stratum causes far less disturbance to the water body and the riverbed ecology than a bridge, thereby protecting the ecosystem to the greatest possible extent.
Furthermore, tunnel construction can reduce local demolitions and has a lesser impact on local residents.
In summary, a tunnel does not obstruct ships, is unaffected by the weather, requires no speed reduction, and does not disturb the ecosystem or residents. This represents a comprehensively optimal solution in technical, economic, and operational terms.
How difficult is it to build a tunnel under the yangtze river?
The Chong-Tai Yangtze River Tunnel is being constructed using the shield (boring) method, involving enclosed construction within the strata under the Yangtze riverbed, and faces numerous challenges.
Firstly, there is immense water pressure. The deepest part of the tunnel is 89 metres below the river's surface, withstanding water pressure of up to 0.9 megapascals, equivalent to a 9-kilogram weight on an area the size of a fingernail.
What is more dangerous is that the geological conditions at the bottom of the river are extremely complex, involving hard calcareous cemented rock and water-rich strata containing methane.
Building a tunnel in such an extreme natural environment requires the use of a giant shield machine. The "Linghang", independently developed by China and tailor-made for crossing the Yangtze River, is the world's largest diameter high-speed rail shield machine, with a cutter head diameter of 15.4 metres, about the height of a five-storey building.
The full name for a shield machine is a "full-face tunnel boring machine". It is a powerful tool for burrowing through the ground, drilling through mountains, and crossing under rivers and seas, known as the "iron pangolin". The shield machine cuts through the rock and soil at the tunnel face by rotating its cutter head, while simultaneously excavating and assembling the tunnel's supporting lining segments to form a completed tunnel.
The "Linghang" not only has top-tier hardware but is also equipped with the world's "most powerful brain"—the I-TBM (Intelligent Tunnelling Boring Machine) control system. Through full-system algorithmic control, it has successfully achieved unmanned intelligent boring.
Additionally, as mentioned above, the Chongming-Taicang Yangtze River Tunnel will also pass through the national-level germplasm resource conservation area for Japanese grenadier anchovy, and Chongming Island is a world-class ecological island.
Therefore, in addition to solving hardware difficulties, the construction of the tunnel must also consider ecological protection issues.
The construction team expertly applied technologies such as slurry separation, battery-powered vehicle transport, and wastewater recycling, implementing green construction techniques of "no slurry on the ground, no muck on the ground" in the ecologically sensitive areas of the Yangtze River to minimise the impact of construction on the riverbed ecosystem and rare fish species, while also achieving resource recycling.
Why build the Chongming-Taicang Yangtze River Tunnel?
Behind the Chongming-Taicang Yangtze River Tunnel is a grand national strategy—the construction of the "Shanghai-Chongqing-Chengdu High-speed Railway along the Yangtze River" (Yanjiang High-speed Railway), starting from Shanghai Baoshan Station, passing through Jiangsu, Anhui, Hubei, Chongqing, and Sichuan, and ending at Chengdu Station.
The entire Yanjiang High-speed Railway line is being built to a high standard of 350 km/h. After completion, the high-speed rail journey from Shanghai to Chengdu will be shortened from over 12 hours to less than 7 hours.
The Chongming-Taicang Yangtze River Tunnel is a critical, controlling "bottleneck" project on this major national strategic artery.
The completion of the Yanjiang High-speed Railway has been included as one of the 109 major engineering projects in the "15th Five-Year Plan" outline.
It is also one of the main east-west corridors in the "Eight Vertical and Eight Horizontal" high-speed railway network, with a total length of approximately 2,100 kilometres, connecting the three major city clusters of the Yangtze River Delta, the middle reaches of the Yangtze River, and the Chengdu-Chongqing area.
At the same time, it will also connect more than 20 small and medium-sized cities along the route to the national high-speed rail network for the first time.
The construction of the Yanjiang High-speed Railway has driven the research, development, and customisation of over 200 units of large-scale equipment such as shield machines and bridge-building machines, giving rise to one piece of "great power heavy machinery" after another.
The laying of steel rails has brought sales orders for 570,000 tonnes of high-strength special steel. Even the precast concrete segments for assembling the tunnels have spurred the creation of a smart manufacturing factory.
The total investment in the entire Yanjiang High-speed Railway exceeds 500 billion yuan (RMB, same currency hereafter), and it is expected to drive a nearly 1.5 trillion yuan increase in the added value of upstream and downstream industries.
With its hard-core strength, China's infrastructure once again pushes the imagination of turning "natural chasms" into thoroughfares to new heights.