Twin TBMs Achieve Millimeter-Precision Rescue Under Yangtze River

Chinese engineers salvaged a $50M tunnel boring machine stuck 177 feet underground beneath the Yangtze River by sending a second TBM from the opposite bank; the two machines docked with only about 2 mm vertical error, saving the Jiangyin–Jingjiang Yangtze River Tunnel project and underscoring advances in precision tunneling.