Group 1 - The construction of seven metro lines in Nanjing has made significant progress as of the end of December [1][3] - The second phase of Line 4 has commenced construction on four stations and a central ventilation shaft, with three stations and a shaft having completed their main structure [1] - For Line 6, project acceptance has been achieved, and it is currently undergoing non-passenger test runs [1] Group 2 - The first phase of Line 9 has completed all main structures, with auxiliary structure construction ongoing [3] - A total of 31 shield tunnels have started, with 30 of them already completed [3] - The first phase of Line 11 has seen 18 stations commence construction, with 17 stations having completed their main structures [3] Group 3 - The Ningma Line has passed project acceptance and is currently in non-passenger test runs [3] - The Ningchao Line (Nanjing section) is advancing preliminary construction preparations for the underground section, while the elevated section is progressing with civil engineering [3] - The Ningyang Line (Nanjing section) has three stations and three elevated sections under construction, with two stations having completed protective structures and one station completing its main structure [3]

Core Insights - The construction progress of multiple subway lines in Qingdao has been reported, indicating significant advancements in the city's infrastructure development [1][2][3] Group 1: Subway Line 7 - The left line shield tunneling of the subway Line 7 Phase II between Blue Ao Road Station and Heshan Road Station has been successfully completed [1] - The total length of Line 7 Phase II is approximately 16.9 kilometers, with 14 stations planned, divided into northern and southern sections [1] Group 2: Subway Line 9 - The first auxiliary structure, the No. 2 wind pavilion retaining pile, at Huicheng Road Station of Line 9 has been successfully completed, laying a solid foundation for subsequent construction [2] - The total length of Line 9 is 16.36 kilometers, with 13 stations, starting from Haixi Village Station to Qianjin Community Station [2] Group 3: Subway Line 15 - The first segment of the top slab at Jingcheng Road Station of Line 15 has been completed, facilitating the subsequent shield tunneling between Jingcheng Road Station and Chunyang Road Station [3] - Line 15 is a key project in Qingdao's third-phase subway planning, with a total length of approximately 30.8 kilometers and 17 stations planned [3]