Wedoany.com Report-Apr. 10, China introduced a massive self-developed tunnel boring machine (TBM) named "Jianghai" for building the world’s longest underwater highway TBM tunnel on Wednesday, April 9, 2025. This machine, boasting a 16.6-meter excavation diameter, stretches 145 meters in length and weighs 5,000 tonnes. It is deployed for the Haitai Yangtze River Tunnel project in Jiangsu Province, eastern China, connecting Haimen in Nantong city to Taicang in Suzhou city beneath the country’s longest river.

The tunnel spans 39.07 kilometers overall, with an 11.185-kilometer underwater segment, of which 9,315 meters will be dug using the TBM. Designed as a six-lane, two-way highway with a 100 km/h speed limit, it will navigate challenging geological layers of silt and fine sand under the riverbed. The tunnel’s deepest point reaches 75 meters, enduring pressure equivalent to 75 tonnes per square meter. You Shaoqiang, chief engineer at China Railway 14th Bureau, noted: “These harsh conditions make the construction process extremely challenging.”

To address these difficulties, "Jianghai" features advanced technology, including a pressure-balanced cutterhead and an intelligent monitoring system for real-time tracking of cutterhead wear, allowing repairs underwater. Meng Defeng, TBM manager, added that dual slurry injection enhances efficiency. Safety measures include a segmented smoke extraction system to reduce fire risks and a rescue vehicle access tunnel linked by corridors to the main structure, ensuring quick response without affecting traffic flow.

Chen Junwei, a project manager, highlighted the tunnel’s innovative aspects, stating: “The tunnel boasts multiple pioneering features in structural design, disaster prevention, equipment, green technology, and intelligent systems, with its construction designed to be close to carbon neutral.” Scheduled for completion in 2028, this project aims to minimize environmental impact while setting new standards in tunnel engineering.

The Haitai Yangtze River Tunnel will strengthen transportation links in the Yangtze River Delta, a vital economic region. You Shaoqiang emphasized its broader significance: “This project will play a pivotal role in promoting regional integration within the Yangtze River Delta and inject significant momentum into the high-quality development of the world-class Yangtze River Delta city cluster.” Upon completion, it will enhance connectivity between Nantong and Suzhou, supporting regional growth.

This ambitious undertaking showcases China’s engineering capabilities through the "Jianghai" TBM and thoughtful design. By tackling complex conditions with cutting-edge solutions, the project promises to deliver a sustainable, efficient highway link, boosting transportation and economic activity in Jiangsu Province and beyond.