On May 22, accompanied by a resounding blast, construction began at the entrance of the Qinghoushan Tunnel on the Panxing Railway, undertaken by China Railway No. 3 Engineering Group. Following the start of construction at the tunnel exit on April 5, the tunnel has now entered the two-way excavation stage, marking a major breakthrough in the construction of the Panxing Railway.

As a key and controlling project of Section 3 of the Panxing Railway, the Qinghoushan Tunnel has a total length of 2,502 meters and a risk level of Grade II, with a design speed of 250 kilometers per hour and a maximum burial depth of 188 meters. The tunnel consists of 985 meters of Grade III surrounding rock, accounting for 39.3% of the total length; 835 meters of Grade IV surrounding rock, accounting for 33.3%; 645 meters of Grade V surrounding rock, accounting for 26%; and 37 meters of open-cut section, accounting for 1.4%. The tunnel has complex geological structures, crossing three faults and one fold structure. Karst is strongly developed in the tunnel area, weak swelling rock exists in the surrounding rock, and groundwater is abundant with strong seasonality, with water inflow reaching 8,410 cubic meters per day in the dry season and up to 31,000 cubic meters per day in the rainy season. The Qinghoushan Tunnel is designed for two-way construction. The entrance section is constructed on a reverse slope, with shallow cover and bedding-parallel strata, and a gully on the surface, posing high safety requirements and great construction difficulty.

Since construction started in September 2020, the tunnel exit has been in a Grade V surrounding rock zone with a horizontal fractured zone, encountering multiple challenges such as water and mud inrushes and broken rock. Following the construction principles of "short advance, strong support, and early closure," the maximum daily advance has been 2.4 meters under the premise of ensuring safety. To accelerate tunnel excavation and ensure completion according to schedule, striving for the early opening of the Panxing Railway, the builders of China Railway No. 3 Engineering Group on the Panxing Railway have given up rest and vacation time, adhered to the "five points and two lines" management approach, taken the "Year of Standardization" campaign as an opportunity, coordinated the deployment of personnel and equipment, ensured steady progress of the project, strengthened technical services, stayed at their posts, worked overtime, and fought on the front line. They overcame difficulties in treating dangerous rocks at the portal, completed the crown ditch, temporary protection of the side and face slopes, excavation of the vertical working face, construction of the guide wall, installation of the large pipe roof, and grouting of the pipe roof. Having met the conditions for tunnel excavation, they started construction at the tunnel entrance on May 22, achieving two-way excavation of the tunnel, which is of great significance for accelerating tunnel construction.

Once the Panxing Railway is completed, Guizhou Province will realize the vision of "high-speed rail access to every city and prefecture." By then, a 1- to 2-hour high-speed rail transportation circle from Guiyang to the central cities of the province's eight cities (prefectures) will be formally established. It is of great significance for promoting regional economic integration, strengthening the internal economic circulation, consolidating the achievements of poverty alleviation, promoting regional economic and social development, and optimizing and improving the layout of the national railway network.