Core Viewpoint - The completion of the Qiaojin Mountain Tunnel, the longest secondary highway tunnel in China, significantly reduces travel time across the mountain and addresses transportation challenges for 110,000 residents during winter snow closures [3][4]. Group 1: Project Overview - The Qiaojin Mountain Tunnel spans 10.07 kilometers, with the main tunnel measuring 9.35 kilometers and a parallel tunnel of 9.36 kilometers [6]. - The project was initiated on December 26, 2021, with a total investment exceeding 1.8 billion yuan [6]. - The tunnel is designed to accommodate a speed of 60 kilometers per hour, adhering to secondary highway technical standards [6]. Group 2: Environmental Considerations - The tunnel's construction was mindful of the ecological impact, particularly as it is located within a giant panda national park [4]. - To minimize ecological disruption, the design of the ventilation and smoke exhaust system was modified from conventional shafts to parallel tunnels [4]. Group 3: Construction Achievements - The project utilized a Tunnel Boring Machine (TBM) for the first time in the construction of a national highway, achieving remarkable progress rates: 50 meters per day, 736 meters per month, and 1,000 meters over 40 consecutive days [4]. - The TBM used for the Qiaojin Mountain Tunnel was repurposed from a previous project, significantly reducing costs [4]. Group 4: Historical Significance - The tunnel is located at an average altitude of 3,000 meters and serves as a critical route for emergency rescue operations during natural disasters, such as the Wenchuan and Lushan earthquakes [4]. - The historical context of the area is highlighted by its association with the Long March, where key leaders of the Red Army traversed the mountain [3].