On May 8, 2026, China unveiled its first domestically developed set of ‘ternary mixed gas’ shield tunneling equipment, designed specifically for pressurized operations. This cutting-edge equipment was officially deployed in the construction of the Jintang Subsea Tunnel, a key component of the Ningbo-Zhoushan Railway and the world’s longest subsea high-speed railway tunnel. Developed by the China Railway 11th Bureau Group, this innovative system enables precise mixing of helium, nitrogen, and oxygen to facilitate the inspection and replacement of cutting tools on the ‘Dinghai’ shield tunneling machine. This capability is crucial for overcoming the challenges posed by ultra-high-pressure operational environments.

The Jintang Subsea Tunnel stretches an impressive 16.18 kilometers, with 11.21 kilometers of its length constructed using shield tunneling methods. The tunnel is subjected to a maximum water-soil pressure of 0.85 megapascals. The newly introduced equipment comprises 113 sub-modules, meticulously engineered to adapt to pressure conditions ranging from 0.5 to 1 megapascal. This adaptability ensures the safety of operators, significantly reduces maintenance intervals, and enhances overall operational efficiency. As a result, it offers a ‘Chinese solution’ to the global challenge of ultra-high-pressure shield tunneling projects.

To date, the shield tunneling section of the tunnel has progressed to 9,362 meters, marking the completion of 83.6% of the total tunneling work. The Ningbo-Zhoushan Railway, spanning approximately 76.4 kilometers and designed for speeds of up to 250 kilometers per hour, is slated for completion in 2028. This milestone will mark the end of the Zhoushan Archipelago’s history without rail connectivity, ushering in a new era of transportation for the region.