World's longest undersea high-speed rail tunnel project passes 4-km boring milestone

(ECNS) -- The “Yongzhou” tunnel boring machine (TBM), operating on the Ningbo side of the Jintang undersea tunnel in Zhejiang Province, has completed over 4,000 meters of excavation as of Monday, with less than one kilometer left before reaching the preset mid-sea junction.

Stretching 16.18 kilometers, the Jintang Tunnel is a core component of the Ningbo-Zhoushan Railway. Upon completion, it will become the world’s longest undersea high-speed railway tunnel. Its 11.21-kilometer shield-driven section is being excavated from the Ningbo and Zhoushan sides by two tunnel boring machines that will meet beneath the sea.

The tunnel’s Ningbo excavation segment spans 4.94 kilometers, with its lowest point reaching 92 meters below the seabed. The domestically developed “Yongzhou” machine is currently boring through the hardest full-face rock section along the undersea route.

The tunnel is a key project of the Ningbo-Zhoushan Railway, which will bring railway service to Zhoushan for the first time once completed.

(By Intern Yang Hongran, Zhang Dongfang)