442-foot Yongzhou TBM completes 83% of Jintang undersea tunnel

China's Yongzhou tunnel boring machine, 14.57 meters in diameter, has excavated over 4 km of the Jintang undersea tunnel between Ningbo and Zhoushan, about 83% of its planned route. Operators steer it remotely from a ground control center, and roughly 4,000 cutters have been replaced so far. The railway is expected to open in 2028.

• The 14.57-meter TBM carries 308 cutters and began work in May 2024
• Over 4 km excavated; next section lies about 93 meters beneath the seabed
• About 4,000 cutters replaced; rock strength reaches 240 MPa
• The 16.18-km tunnel opens in 2028, cutting Ningbo–Zhoushan rail to 26 minutes