On September 11, the right tube of the Niubo No. 2 Tunnel on the Mengla-Luchun Expressway project, constructed by the Fifth Company of China Railway No. 5 Engineering Group, was successfully holed through, providing valuable parameters and construction experience for the subsequent full breakthrough of the tunnel's left tube and laying a solid foundation for the early opening of the entire expressway.

The Niubo No. 2 Tunnel is located in Zhe'e Village, Niukong Township, Luchun County, Honghe Prefecture, Yunnan Province. The right tube of the tunnel has a total length of 1,770 meters. The tunnel's geological conditions are poor, with Grade IV and Grade V surrounding rock accounting for as much as 62% and 38% respectively. The surrounding rock grade changes frequently, posing high safety control risks and great construction difficulties.

Since the start of construction, the Mengla-Luchun Project Department of China Railway No. 5 Engineering Group has given full play to the leading role of Party building, always prioritizing safety, quality, environmental protection, water and soil conservation alongside progress, planning ahead and racing against time to meet the schedule. During construction, all participating personnel united as one and overcame poor construction conditions, a long rainy season and a tight schedule. They tackled multiple construction challenges, including complex and variable surrounding rock, long-distance ventilation, complex geology, high-temperature operations and tunnel water inflow. Through reasonable construction plans, they broke down construction tasks, reversed the schedule, and made careful arrangements in terms of personnel, equipment and materials, giving priority to resource investment. They continuously overcame construction difficulties, ensuring safe and steady progress of construction and ultimately achieving the smooth breakthrough of the tunnel.

The Mengla-Luchun Expressway is one of the "border routes" in the "five vertical, five horizontal, one border, two rings and twenty links" expressway network layout plan and an important component of Yunnan Province's expressway network. It plays an important role in Yunnan's provincial expressway network by "linking the province's southwestern border areas and radiating both inside and outside the national gateway." Once completed, the project will improve local transportation infrastructure conditions, promote the efficient and smooth flow of people and goods in border areas, help ethnic minority communities improve their quality of life, and is also of great significance for further maintaining border stability.