People's Daily inform China National Railway Group Guangzhou-Zhanjiang high-speed railway officially entered "sea piercing` step. This is construction of Zhanjiang Bay submarine tunnel. This start a few days ago.

Submarine tunnel is 2.5 kilometer. Maximum buried depth of TBM tunneling is 31 meter. Maximum water depth is 20.8 meter. Single tube double track tunnel.

China Railway Design Group prepare construction plan for TBM boring. Safety technical measures and emergency management plans review by experts.  "Guangdong-Hong Kong-Macao Greater Bay Area Academician and Expert Studio"  major difficult scientific research and technological breakthroughs.

http://finance.people.com.cn/BIG5/n1/2022/0321/c1004-32379974.html