Massive 442-foot tunnel boring machine in China starts carving out the world’s longest undersea railway tunnel

The 442-foot-long tunnel boring machine, named Yongzhou, is working on a project that will eventually connect Ningbo and Zhoushan in eastern China.

It’s equipped with hundreds of cutting tools and technology that allows engineers to monitor its progress from miles away.

And the conditions it’s facing underground are proving to be seriously challenging.

The enormous machine is being controlled from miles away

The machine, which measures around 442 feet (135 meters) long, is working on the Jintang undersea tunnel in China’s Zhejiang Province, and it looks like something from the future.

Rather than having operators control everything from inside the Chinese tunnel, engineers can steer Yongzhou remotely from a ground control center approximately two miles away.

Cameras and smart sensors keep track of the machine’s cutting equipment, operating conditions, and excavation progress.

The technology can even send alerts directly to engineers’ smartphones if something goes wrong, including unusual pressure changes, cutterhead torque issues, or movement in the tunnel segments.

According to Dong Bing, chief mechanical engineer of the Yongzhou Railway project, the machine’s intelligent system is more sensitive than people.

Yongzhou has already excavated more than 13,123 feet (4,000 meters) from the Ningbo side, completing around 83 percent of its planned section.

It’s facing some seriously tough underground conditions

The machine isn’t simply digging through ordinary dirt.

Around 70 percent of its route on the Ningbo side consists of challenging geological conditions, including extremely hard rock, soft soil, and sections where it has to cut through both materials simultaneously.

Its cutting equipment has to deal with rock strength reaching 240 megapascals, which is more than eight times the strength of ordinary concrete.

Yongzhou has 308 cutters attached to its enormous cutting head, but even those have taken a beating.

Around 4,000 cutters have already been replaced during the excavation process, with some needing to be changed after just a few dozen centimeters of progress in particularly difficult sections.

The machine is also expected to reach the deepest part of its route by the end of 2026.

The undersea railway could transform journeys in China

The Jintang undersea tunnel will stretch approximately 10 miles (16.18 kilometers), making it the world’s longest undersea high-speed railway tunnel once completed.

It forms part of the wider Ningbo-Zhoushan Railway project, which will connect the mainland with Zhoushan and bring railway services to the island for the first time.

Yongzhou isn’t the only enormous machine involved, either.

Another tunnel boring machine, named Dinghai, is excavating from the Zhoushan side, with the two machines eventually expected to meet beneath the seabed.

Once their work is complete, both machines will be dismantled inside the tunnel.

The railway is expected to open in 2028, potentially cutting the high-speed rail journey between Ningbo and Zhoushan to just 26 minutes.

That’s a pretty impressive payoff for a project involving one of the biggest and most technically demanding tunnel excavations currently underway.