2mm Precision: China Saves $50M TBM in Yangtze River Tunnel Rescue

A daring underground rescue has saved a $50 million megaproject from certain abandonment. Beneath the country’s largest river, a massive tunnel boring machine (TBM) met its stranded twin with a staggering vertical error of just 2mm, proving that even the most catastrophic engineering failures can be reversed with extreme precision.

China Yangtze River Tunnel TBM Recovery: A High-Stakes Rendezvous

According to state media reports on Wednesday, engineers have achieved a technical feat previously thought impossible. They successfully recovered a shield tunnelling machine (STM) that had been entombed under the Yangtze River since February 2023. The rendezvous was so precise that it showed zero horizontal deviation and less than 0.078 inches of vertical error.

The crisis began when a 16m-diameter machine ground to a halt midway through the 6.4km Jiangyin-Jingjiang Yangtze River Tunnel project. Stuck at a depth of 54 metres under crushing water pressure, the $50 million asset was effectively lost, threatening the viability of the entire dual six-lane highway project linking Jiangsu province's industrial zones.

From 'Steel Tomb' to Engineering Benchmark

The recovery team didn't give up. They deployed a second TBM from the opposite direction to excavate toward the stranded unit. This mid-river docking strategy turned a potential multi-million dollar write-off into a defining moment for modern deep-underground engineering.