Through Mountains and Beneath the Sea: A Gen-Z TBM Operator's Millimeter by Millimeter Precision

BEIJING, Nov. 13, 2026 /PRNewswire/ -- A news report from China.org.cn on the Jintang undersea tunnel of the Ningbo-Zhoushan (Yongzhou) Railway:

Beneath the seabed off the coast of Ningbo in southeastern China's Zhejiang Province, a tunnel boring machine (TBM) over 100 meters in length and weighing several thousand tons is steadily at work. It bores through the rock while simultaneously installing the precast segments that form the tunnel's lining.

At the "controls" of this steel giant sits Cheng Jie, a girl born in 2000, and China's very first female operator of a super-large-diameter TBM. She speaks softly, but once in the control cabin, her hands are steady and sure.

Cheng Jie is working on the Jintang undersea tunnel, part of the Ningbo-Zhoushan (Yongzhou) Railway. Upon completion, the undersea tunnel will be the world's longest undersea high-speed railway tunnel. Its geological conditions are among the most complex, making the tunnel's construction one of the most challenging projects of its kind. In some stretches, the rock is several times harder than ordinary concrete. As the TBM battles its way through the hard rock, its cutters wear down rapidly and require frequent replacement — sometimes after advancing just several dozen centimeters. Each time, Cheng Jie and her coworkers need to work closely with the cutter replacement crews, adjusting the angle of the cutterhead and maintaining pressure balance throughout the operation.

When operating the TBM's thrust system, Cheng Jie fixes her eyes on the screen, tracking the curve that represents the tunnel's design alignment, while monitoring real-time deviation readings. Whether the tunnel stays precisely on course depends in large part on how Cheng controls the thrust system's 20 sets of hydraulic cylinders. Even an adjustment of just tens of tons in thrust or a stroke difference of one or two millimeters can instantly shift the TBM's attitude. To ensure that the tunnel extends along its designed alignment, Cheng Jie and the team fine-tuned their operations to achieve millimeter-level precision.

"I sit right here, like an unassuming ballast stone, quietly holding my ground and steadily doing the job I'm here to do," Cheng says.

Cheng Jie is not alone in her dedication to this monumental project. Dong Bing, the project's chief mechanical engineer, keeps close watch on construction parameters day in and day out. Several cutter replacement crews take turns traveling through a shuttle chamber between the living cabin and the TBM, carrying out replacement work around the clock. Some mechanics remain firmly on the front lines, constantly looking for ways to increase efficiency. Currently, only a few hundred meters of excavation on the Ningbo-side remain to be finished. When the Yongzhou Railway officially opens, it will bring an end to the history of the Zhoushan Islands having no railway connection.

Take a step back, and you'll find that Cheng Jie is just one of many skilled workers who share the same spirit. Tang Haiwei, who has spent 27 years working with engines, conquered the challenge of measuring the temperature of high-temperature moving components inside an engine. Sun Jingnan, who has wielded a welding torch for more than three decades, uses precision welding to ensure the safety of China's Fuxing high-speed trains. Zhang Zhonghua, who has explored circuit boards since his teenage years, safeguards the reliable operation of port machinery through every component he handles and every blueprint he works with.

Some dedicate themselves to a giant TBM; others to a tiny circuit board. They rarely appear in the spotlight, yet day after day, they can always be found on site, solving problems and getting work done.

Be it a railway traversing mountains and crossing the sea, or a port handling vast volumes of cargo around the clock, every large project ultimately comes down to individual workers, countless millimeter-level calibrations and teams working in relays, day and night. What makes it possible to cross mountains and span the sea is not steel machinery alone, but the perseverance and craftsmanship of these frontline workers.

China Mosaic 
http://www.china.org.cn/video/node_7230027.htm 

Through Mountains and Beneath the Sea: A Gen-Z TBM Operator's Millimeter by Millimeter Precision
http://www.china.org.cn/video/2026-11/13/content_118773376.shtml 

SOURCE China.org.cn