China Merchants Chongqing Communications Technology Research&Design Institute Co. Ltd. Chongqing 400067 China;
China Merchants Chongqing Communications Technology Research&Design Institute Co. Ltd. Chongqing 400067 China;
Chongqing Rail Transit(Group)Co. Ltd. Chongqing 401120 China;
Low gas; Tunnel construction; Construction technology; Safety management;