On November 4, the reporter learned from the Chongqing-Guizhou Railway Co., Ltd. that the Chenjiayuanzi Tunnel, a low-gas long tunnel on the Chongqing-Qianjiang section of the Chongqing-Hunan High-Speed Railway, was successfully holed through, laying a solid foundation for the completion and opening of the entire line as scheduled.

The Chenjiayuanzi Tunnel is located in Wulong District, Chongqing. It is a double-track single-tube tunnel with a total length of 3,440 meters and a maximum burial depth of 327 meters. The tunnel area passes through coal-seam strata, with gas sections accounting for 83% and Class IV and V surrounding rock accounting for 89%. The safety risks of collapse and gas explosion are extremely high, and the construction safety pressure is great, bringing enormous challenges to the construction.

The Chongqing-Qianjiang section of the Chongqing-Hunan High-Speed Railway is an important part of the Xiamen-Chongqing Corridor among the "Eight Vertical and Eight Horizontal" lines in the national medium- and long-term railway network plan. It starts from Chongqing Station, passes through Yuzhong, Nan'an, Banan, Nanchuan, Wulong, Pengshui and other districts and counties, and ends in Qianjiang District, Chongqing, with a designed speed of 350 kilometers per hour. It connects with the Qianjiang-Zhangjiajie-Changde Railway and the Changde-Yiyang-Changsha Railway. The line links the urban agglomerations in the middle reaches of the Yangtze River and serves as a high-speed passenger transport corridor among the Chengdu-Chongqing urban agglomeration, the urban agglomerations in the middle reaches of the Yangtze River, and the West Coast urban agglomeration.