The world's largest high-speed rail shield machine 'Linghang' has completed a record-setting bore under the Yangtze River, paving the way for bullet trains to cross 89 metres beneath the waterway without slowing down.
On July 30, 2026, a 4,000-tonne tunnelling machine named Linghang broke through the final wall of rock and soil on the far side of China's Yangtze River, completing the underwater bore of the Chongming–Taicang tunnel. The breakthrough marks the first time a high-speed rail tunnel has been bored beneath the Yangtze, and it sets the stage for 350 km/h bullet trains to cross one of the world's great rivers without reducing speed.
A Machine the Size of a Five-Storey Building
Linghang — Chinese for 'leading the voyage' — is China's largest domestically developed shield tunnelling machine built specifically for high-speed rail. Its rotating cutter head spans 15.4 metres in diameter, roughly the height of a five-storey building. The machine stretches 148 metres from nose to tail and is equipped with an intelligent control system known as I-TBM, which monitors ground pressure, alignment and cutting torque in real time.
Starting from the Chongming Island side, Linghang bored continuously for more than 11 kilometres under the river bed in a single unbroken drive — a record for any 15-metre-class shield machine worldwide. At its deepest point the tunnel passes 89 metres below the surface of the Yangtze, where the machine had to withstand enormous water pressure and navigate complex geology including soft silt and gravel layers.
Part of a Transcontinental Railway
The 14.25-kilometre Chongming–Taicang tunnel is a critical section of the Shanghai–Chongqing–Chengdu high-speed corridor, one of China's most ambitious east–west rail routes connecting the Yangtze River Delta to southwestern China. Once the full line is operational, trains will be able to cross beneath the Yangtze at a design speed of 350 km/h — a world first for an underwater railway tunnel at that speed.
For Shanghai's Chongming district — an island of over 700,000 people — the tunnel ends decades of isolation from the mainland high-speed network. Travel time from Chongming to Shanghai's Baoshan Railway Station will drop to just 17 minutes, transforming the island's connectivity to the wider Yangtze Delta region.
What This Means for Metro Tunnelling Worldwide
Shield tunnelling technology like the kind used by Linghang is the same family of engineering that builds underground metro lines in cities around the world. In Bengaluru, Namma Metro's Pink Line includes a 13.76-kilometre underground section from Dairy Circle to Nagawara that will require tunnel boring machines to navigate beneath dense urban neighbourhoods. India's most dramatic underwater metro tunnel — the Kolkata Metro's East–West Line crossing under the Hooghly River — used a smaller but conceptually similar shield machine.
The Yangtze breakthrough demonstrates how far TBM technology has advanced: larger diameters, longer continuous drives, deeper depths, and intelligent monitoring that reduces risk. As Indian cities expand their metro networks underground, these advances in shield tunnelling directly inform the engineering playbook available to projects like Namma Metro Phase 2.
Key Numbers
- Tunnel length: 14.25 km total, including 11+ km continuously under the Yangtze River
- Depth: 89 metres below the river surface at the deepest point
- TBM 'Linghang': 15.4 m cutter head diameter, 148 m long, ~4,000 tonnes
- Design speed: 350 km/h (world's first underwater HSR tunnel at full speed)
- Impact: Chongming to Shanghai Baoshan in 17 minutes; full tunnel completion expected by end of 2026
Sources
- Guangming Online — China's mega tunnelling machine completes breakthrough
- Global Times — World's largest HSR shield machine passes under Yangtze
- People's Daily — Linghang successfully underpasses the Yangtze River
- South China Morning Post — China sets record with HSR breakthrough
- Interesting Engineering — World's largest tunnelling machine sets excavation record