People newspaper inform Zhanjiang Bay Undersea Tunnel Project is a key part of Guangzhou-Zhanjiang High-speed Railway.

Submarine railway tunnel is 9,640 meters and 7,551 meters excavated with Tunnel Boring Machine. The excavation diameter is 14.33 meters. It has two railway lines in one tube. Design speed of trains in tunnel is 350 kilometers per hour.

China Railway 14th Bureau excavated in one direction for entire tunnel.

http://finance.people.com.cn/BIG5/n1/2024/0319/c1004-40198559.html