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 Points - The completion of the shield tunnel construction at Jiangbei Citizen Center Station marks a significant progress in the Nanjing Metro Line 4 Phase II project, specifically the cross-river shield project [1] - The shield receiving well has a wall thickness of 1.5 meters and an inner diameter of 12.1 meters, with a depth of 45.28 meters, facing high leakage risks due to the surrounding sandy and highly permeable soil [1] - The project team employed a layered demolition method to ensure efficiency while minimizing the impact on surrounding structures [1] Project Details - The Phase II of Line 4 starts from Longjiang Station, traverses through various areas including the Jiangxinzhou, and ends at Zhenzhuquan East Station, covering a total length of approximately 10 kilometers, all underground with 6 stations [1] - The cross-river tunnel, a critical segment, extends 3062.6 meters with the lowest point being 68.58 meters below the Yangtze River surface, setting a record for the deepest cross-river metro tunnel in the Yangtze River Delta [1] - Upon completion, the Phase II of Line 4 will enhance the urban cross-river metro network, alleviate traffic pressure, and provide more convenient public transportation services for citizens [1]