The Yiliang Tunnel, China's longest high-speed railway tunnel on the Chongqing-Kunming High-Speed Railway in the southwest, was drilled through on Wednesday. Located in Zhaotong City of Yunnan Province, the Yiliang Tunnel is 24.8 kilometers in length, and is designed for speeds up to 350 kilometers per hour. For the time being, it is also the tunnel for fastest speed of railway trains in China. The tunnel goes through the interior of Wumeng Mountains, known as a geological museum for the complex terrains and geological conditions there, which posed tremendous challenges for the constructors. "To tackle the highland stress and rock burst, we carried out measures of pre-stress relief, spray application of fiber-reinforced concrete, increasing prestressed anchor rods and more, effectively ensuring construction safety and facilitating the project progress," said Rao Shengbin, a project leader from China Railway Construction Bridge Engineering Bureau Group Co.,Ltd. The Chongqing-Kunming High-Speed Railway is 700 kilometers in total length, with 388.6 kilometers in Yunnan. It is Yunnan Province's first high-speed railway with a designed speed up to 350 km per hour, and it is now in its final stage of construction. Once completed, the travel time between Chongqing and Kunming will be shortened to around two and a half hours, significantly enhancing local connectivity, and promoting high-quality economic and social development along the route. SHOTLIST: FILE: Zhaotong City, Yunnan Province, southwest China - Date Unknown 1. Aerial shot of mountains; 2. Various of tunnel construction in progress; 3. SOUNDBITE (Chinese) Rao Shengbin, project leader, China Railway Construction Bridge Engineering Bureau Group Co., Ltd (ending with shot 4): "To tackle the highland stress and rock burst, we carried out measures of pre-stress relief, spray application of fiber-reinforced concrete, increasing prestressed anchor rods and more, effectively ensuring construction safety and facilitating the project progress."; 4. Various of construction in progress; 5. Aerial shots of mountains, construction in progress; 6. Aerial shots of trains running. [Restrictions: No access Chinese mainland]