At 10 a.m. on April 27, with the sound of a blast, the Baiyun Tunnel—the only low-gas tunnel on the entire Longchang–Xuyong Section Capacity Expansion and Renovation Project of the Longhuang Railway (hereinafter referred to as the Longhuang Railway Longxu Section)—was successfully holed through, laying a solid foundation for the completion and opening of the Longhuang Railway Longxu Section.

It is understood that the Baiyun Tunnel is located within Fuji Town and Niutan Town, Luxian County, Luzhou City. The area is a low-mountain and hilly region with considerable topographic relief and complex geological, climatic, and hydrological conditions. It contains coal mine goaf areas, bedding-parallel structures, shallow cover, and harmful gases, as well as special geotechnical conditions such as soft soil.

"The Baiyun Tunnel passes beneath the Yuchan Mountain Scenic Area and is a low-gas tunnel with a total length of 2,042 meters and a maximum burial depth of about 130 meters. The gas-bearing section reaches 1,234 meters, accounting for 60% of the tunnel's total length," said Xiao Yao, project manager of the First Branch of the Longhuang Railway Project of Sichuan Road & Bridge Railway Construction Co., Ltd. The tunnel portal is also close to the South Sichuan Intercity Railway, with the nearest straight-line distance being only just over 200 meters, which means conventional blasting cannot be used for construction at the portal.

Xiao Yao said that in the face of challenges such as high technical requirements and great construction difficulty, the participating units adopted both blasting and mechanical excavation methods, driving from both ends, and strictly implemented upgraded management for gas tunnels, overcoming severe tests including complex geological conditions, fractured surrounding rock, and difficult construction management. For example, a combination of manual detection and automatic monitoring was adopted, with five dedicated gas inspectors assigned to track and detect around the clock. To effectively prevent potential geological risks and safely pass through the fractured zone, methods such as advanced horizontal drilling, ground-penetrating radar, and TSP detection were fully utilized to carry out dynamic management of tunnel surrounding rock support and to adopt advanced support reinforcement measures.

Yang Zhonggang, chief engineer of the Longhuang Railway Command of Sichuan Road & Bridge Group, introduced that since the start of the Longhuang Railway Longxu Section Capacity Expansion and Renovation Project, 15 of the 23 tunnels along the entire line have been holed through, and 90% of the total works have been completed. The longest tunnel on the entire line, the Huguo Tunnel, is expected to be holed through in May; about 90% of the total bridge works have been completed, and the longest bridge on the entire line, the Luzhou Tuojiang Grand Bridge, is expected to be closed in May; about 75% of the total subgrade works along the entire line have been completed, with the remaining sections progressing in an orderly manner; and the track-laying and girder-erection works and station building works along the entire line have been launched successively.

As an important component of the western railway corridor in the national "Overall Plan for the New Western Land-Sea Corridor," the Longchang–Xuyong Section of the Longhuang Railway has a design speed of 120 km/h. It is a convenient freight transport corridor for Sichuan Province to reach the sea southward, a corridor for the exchange of light and fast goods between the Chengdu-Chongqing and South Sichuan regions and the Beibu Gulf region, and a trunk railway that mainly handles freight while also accommodating passenger transport. Once the project is completed and put into operation, it will gradually improve the supporting railway systems in the region, enhance the region's comprehensive transport efficiency, and be of great significance for Sichuan's full integration into the joint construction of the "Belt and Road."