On March 26, the Jinyun Mountain Tunnel in the Bishan–Hufeng section of Chongqing Rail Transit Line 27 was successfully holed through. This is the first long, large mountain-crossing tunnel on the entire line to be completed, laying a solid foundation for the smooth opening of Rail Transit Line 27.

　　The Jinyun Mountain left-line tunnel is a double-tube, single-track tunnel with a total length of approximately 3.2 kilometers. The tunnel passes through complex geological structures with alternating layers of various rock and soil types and abundant groundwater. It has successively crossed more than 26 high-risk construction areas, including large coal-mine goafs, faults, fracture zones, gas, and water-rich karst development zones, making it a key node project of Line 27 subject to high risk and heavy monitoring.

　　To overcome construction challenges, the Line 27 project department joined forces with all parties concerned. By organizing expert guidance, optimizing construction organization, strengthening resource allocation, tackling technical difficulties, and strictly controlling the safety and quality red lines, and by establishing a professional advanced geological forecasting team to accurately detect geological conditions and develop targeted technologies and processes, the tunnel was safely holed through 11 months ahead of the expected schedule, laying a solid foundation for subsequent construction.

　　Chongqing City Transportation Development & Investment Railway Group stated that the successful holing-through of the Jinyun Mountain Tunnel has laid a solid foundation for the smooth opening and operation of Rail Transit Line 27. Once the project is open to traffic, it will quickly connect Bishan District, Shapingba District, Jiulongpo District, Yuzhong District, Nan'an District, and Banan District, linking important gateway hubs such as Shapingba Station, Chongqing Station, and Chongqing East Station, and enabling rapid transfer between internal and external urban transportation. This is of positive significance for Chongqing's acceleration of building a modern, high-quality, comprehensive, three-dimensional transportation network.