Engineers in China are steering Yongzhou, a 442-foot-long machine that bores tunnels, from a surface control center about two miles from where it is digging. Working on the Jintang undersea railway tunnel between Ningbo and Zhoushan, the machine is monitored through cameras, sensors, and real-time alerts. Personnel remain onboard to supervise operations despite the remote-control capability.
Since beginning operations in May 2024, Yongzhou has advanced more than 4,000 meters from Ningbo, completing approximately 83 percent of its planned excavation. It is approaching a section 93 meters beneath the seabed and is expected to reach the deepest section by the end of 2026.
Nearly 70 percent of its Ningbo-side route presents unfavorable ground conditions, including hard rock, soft soil, and mixed sections. Equipped with 308 cutters, the machine has required around 4,000 cutter replacements so far. In particularly difficult stretches, a cutter may need replacement after only a few dozen centimeters of progress.
Maintenance relies on a pressurized chamber that enables technicians to live under pressure and work in shifts for up to 28 days, limiting repeated compression and decompression. During the system’s first use in February, nine divers worked in three groups over 22 days. They replaced 46 cutters approximately 75 meters below the seabed.
Yongzhou will eventually meet Dinghai, a second machine excavating from Zhoushan, after which both will be dismantled inside the tunnel. The Jintang tunnel extends about 10 miles. The railway is expected to open in 2028, introducing rail service to Zhoushan and reducing the Ningbo–Zhoushan high-speed journey to 26 minutes.
