Colossal tunnel boring machine unveiled for undersea railway construction

A tunnel boring machine named Yongzhou rolls off the production lines on Feb 26 in Changsha, the capital city of Hunan province. [Photo/Ningbo Daily]

The construction of the Jintang Undersea Tunnel, the world's longest and widest undersea high-speed railway tunnel, is set to receive a significant boost with the introduction of a monumental tunnel boring machine.

Unveiled on Feb 26 in Changsha, the capital city of Hunan province, the tunnel boring machine, named Yongzhou, is poised to be transported to Ningbo, Zhejiang province for its crucial role in the construction of the Jintang Undersea Tunnel. This tunnel is a vital component of the Ningbo-Zhoushan Railway, a high-speed railway that will link Ningbo with the neighboring island city of Zhoushan.

The colossal tunnel boring machine, a collaborative effort between China Railway 14th Bureau Group and China Railway Construction Heavy Industry Group, measures 135 meters in length and weighs 4,350 metric tons. Equipped with 308 specially designed cutters, it boasts construction capabilities that meet global standards.

The Jintang Undersea Tunnel spans a total length of 16.18 kilometers from Ningbo's Beilun district to Jintang town in Zhoushan, with a maximum depth of 78 meters.

To accelerate the construction process, two tunnel boring machines are simultaneously excavating from both the Ningbo and Zhoushan sides. These machines will ultimately meet and connect at the seabed before being disassembled to complete the tunnel construction. The precision required for their docking is an error of no more than 20 millimeters, approximately equivalent to the diameter of a five-cent coin.

The newly developed Yongzhou tunnel boring machine will be responsible for the Ningbo side of the project.

The Ningbo-Zhoushan Railway, extending approximately 77 km, is designed for a maximum speed of 250 km/h. Once operational, it will mark the end of Zhoushan's history of being inaccessible by railway. Traveling from Ningbo to Zhoushan via high-speed rail will take just 26 minutes, while the journey from Hangzhou to Zhoushan will be achievable in 77 minutes.