On September 14, the exit of the Nijiacun Tunnel on the Section 7 (pre-station) project of the Yunnan-Guizhou segment of the Chongqing-Kunming High-Speed Railway, constructed by China Railway Shanghai Engineering Group, was successfully holed through 18 days ahead of the scheduled milestone. This marks the first working face of the Nijiacun Tunnel, a controlling works of the section, to be holed through, signifying a phased victory in the tunnel's construction and laying a solid foundation for the full-line breakthrough in the next stage.

The Nijiacun Tunnel is located in Hekou Town, Xundian County, Kunming City, with a total length of 10.3 kilometers. The entire line is built to the standard of a double-track high-speed railway, with technical standards of a Grade I railway and a design speed of 350 km/h. The tunnel exit section is 985 meters long and is designed for construction using the three-bench method. The surrounding rock in the area traversed by the tunnel is fractured; the rock mass is generally relatively soft, with a high proportion of developed joints and fissures and poor stability, making collapse and rockfall likely during construction, with high safety risks and great construction difficulty.

To ensure construction safety and quality and to expedite progress, the construction unit has continuously advanced standardized and intelligent operations since the start of construction. By standardizing operating standards, construction techniques and methods, and tooling and equipment, the various process flows at the Nijiacun Tunnel exit have been optimized and refined. An information-based dispatch and command center has been established, equipped with a facial recognition system, pedestrian access system, and vehicle barrier system, enabling real-name registration for entry and exit, precise personnel positioning, and real-time monitoring of personnel movements inside the tunnel. Information systems such as automated monitoring of toxic and harmful gases, an LED display system, and an emergency telephone system have been installed to enable real-time display of construction information inside the tunnel.

The Chongqing-Kunming High-Speed Railway is an important component of the Beijing-Kunming Corridor, one of the main corridors of the national "Eight Vertical and Eight Horizontal" high-speed railway network. Once completed, the Chongqing-Kunming High-Speed Railway will further improve the national comprehensive multi-dimensional transport network and strengthen the connection between the Chengdu-Chongqing economic circle and the Central Yunnan urban agglomeration. At that time, counties and districts in Yunnan Province such as Yanjin, Yiliang, Zhaotong, Huize, and Xundian will be able to reach downtown Kunming and Kunming Changshui Airport directly via the Chongqing-Kunming High-Speed Railway, greatly improving travel conditions for people along the line and promoting high-quality economic and social development in the areas along the route.