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On April 20, the right lane of the Nantian Tunnel on the Guangxi Nantian Expressway, constructed by the Third Company of China Railway First Group, was successfully completed. The completion ceremony was held at the exit of the Nantian Tunnel in Liupai Town, Tian’e County, marking a milestone achievement in the construction of the Nantian Expressway. The right lane of the Nantian Tunnel is 1672 meters long, while the left lane is 1663 meters long. It is located at the border between Nandan and Tian’e counties, which is why it is called the Nantian Tunnel. The Nantian Tunnel is a tunnel developed in a karst area, with complex geological conditions and particularly poor rock quality – it consists entirely of carbonaceous shales. The tunnel has to pass through more than 40 karst caves, many of which are quite large, and there is an abundance of groundwater; the daily water inflow into these caves amounts to 160,000 cubic meters. The carbonaceous shales soften when exposed to water and break down into mud, which can lead to sudden mudflows and water surges. It is one of the four high-risk tunnels along the Nantian Expressway, characterized by the most severe karst phenomena and highest water inflow levels. The tunnel construction conditions were extremely difficult; the access road, which took 8 months to build, crosses a 150-m-high cliff and is considered the most challenging access road for the Nantian Expressway. Construction on the Nantian Tunnel began on May 6, 2020, using a twin-tunneling method. In tunnel construction, the Nantian Expressway project adheres to the principle of \"replacing manual labor with machinery and reducing the need for workers through automation.\" It makes extensive use of large-scale, automated, and intelligent construction equipment, including the ZML160 multi-functional advanced geological horizontal drilling rig, fully computerized three-arm rock drilling units, multi-functional steel arch frame installation units, the YQK4 type self-propelled hydraulic trestle with integrated arch formwork, and multi-functional waterproof membrane laying units. Additionally, new technologies and equipment such as energy-focused hydraulic smooth blasting, high-molecular transparent sealing plates for the secondary lining ends, and laser-guided electromagnetic welding of heat-resistant gaskets are employed. These elements together form a comprehensive set of mechanical systems for tunnel construction, helping to reduce construction safety risks and labor intensity. This approach ensures that \"equipment quality guarantees process quality, process quality guarantees product quality, and product quality guarantees safety,\" thus promoting the high-standard construction of the Nantian Expressway. During construction, the project strictly adhered to the construction principles of \"advance the support in advance, carry out thorough grouting, keep excavation steps short, provide strong support, close sections early, seal them promptly, conduct frequent measurements, and complete lining work quickly\". By excavating one section at a time and providing support for it immediately, progress was made step by step, ensuring that the tunnel was completed safely and on schedule. The Nandan-Tian’e Expressway is located in Nandan County and Tian’e County, Hechi City, in the northern part of the Guangxi Zhuang Autonomous Region. It forms part of Route 2 in the layout plan for the Guangxi Expressway Network (2018–2030); it is connected to the G75 Lanhai Expressway in the east and to the G69 Yinbai Expressway in the west. Once the project is completed and opened to traffic, Tiemo County, the last county in Guangxi without access to high-speed roads, will be connected to the province’s high-speed road network. This will ensure that all counties in Guangxi have access to high-speed roads, reducing the distance between Tiemo County and cities such as Hechi as well as the provincial capital, Nanning, and thereby changing the long-standing situation of poor transportation conditions in Tiemo County. (Zhang Tejun, Sun Qinkē, Zhang Xijie) Source: Infrastructure Information