Recently, 143 meters below the ground surface, at the assembly cavern construction site of the Chongqing Yangtze River Tunnel on the Chongqing-Qianjiang section of the Chongqing-Hunan High-Speed Railway, machines roared and vehicles came and went, with busy construction workers everywhere.

The Chongqing Yangtze River Tunnel is a key control project for the entire Chongqing-Qianjiang section of the Chongqing-Hunan High-Speed Railway. It is designed as a single-tube, double-track high-speed railway tunnel with a total length of 11,942 meters. Among these, the mining method section is 8,007 meters, the shield tunneling section is 3,845 meters, and the cut-and-cover section is 90 meters. This is the first high-speed railway shield tunnel to cross the Yangtze River, hailed as "the first high-speed railway tunnel across the Yangtze River," and it is also the country's longest underwater high-speed railway tunnel. The tunnel as a whole highlights the complex characteristics of passing through the city, the river, water, and mountains.

"The project is the first to use a large-diameter shield tunneling machine for lifting, assembly, launching, and dismantling inside a mountain cavern. There are no precedents at home or abroad, and no industry experience to draw on, filling a gap in the field," said the project manager. Since entering the site for construction in December 2021, the project department has strictly implemented standardized operations, raised safety protection standards, increased manpower and material resources for safe construction, optimized construction plans, overcome the impact of the rainy season, and advanced project construction in an orderly manner to ensure construction quality and safety.  

According to the construction contractor China Railway 14th Bureau Group, as of now, the concrete works of the shield assembly cavern of the Chongqing Yangtze River Tunnel have been completed, and the removal of the trolley formwork is underway. Next, the in-tunnel assembly of the shield tunneling machine will be carried out to ensure the smooth launching of the machine. According to Chongqing Railway Investment Group, the Chongqing-Qianjiang section of the Chongqing-Hunan High-Speed Railway is an important part of the Xiamen-Chongqing corridor in China's "Eight Vertical and Eight Horizontal" high-speed railway network plan. Once the project is completed, travel time from Qianjiang, Chongqing to the central urban area will be shortened from the current 4 hours to less than 1 hour, greatly improving travel conditions for residents along the line.