On May 13, the "Ningwu" shield tunneling machine with an excavation diameter of 9.33 meters rolled off the production line in Changsha, Hunan Province. It will soon be transported to Nanjing and used for the shield-driven section of the Nanjing South Tunnel in the Ningwu Railway capacity expansion and renovation project, marking important progress in the construction of the project.

The Nanjing South Tunnel is a controlling project of the entire Ningwu Railway capacity expansion and renovation project. It crosses Qinhuai District, Yuhuatai District and Jiangning District of Nanjing, passes beneath trunk railways such as the Nanjing–Anqing high-speed railway, the Beijing–Shanghai high-speed railway and the Shanghai–Chengdu railway, as well as major traffic arteries such as Ningdan Highway and Niushou Avenue. With a total length of 14.442 kilometers, it is a single-tube single-track tunnel designed for a speed of 120 kilometers per hour.

The shield-driven section of the tunnel is about 2.4 kilometers long. The shield machine will be launched from the Meixiang Road working shaft in Yuhuatai District and will terminate at the existing Hanfushan tunnel in Jiangning District for reception. It will successively pass beneath the Nonghua River and the Airport Expressway, cross over Metro Line S1, run parallel with Metro Line S3 over a long distance, and pass beneath the Qinhuai New River and the existing Beijing–Shanghai high-speed railway tunnel at Hanfushan, among other structures. It will traverse strata such as argillaceous sandstone and silty sandstone, and the section is characterized by numerous water bodies and complex surface and underground environments. In particular, where the shield machine passes beneath the Qinhuai New River section, the minimum cover is only 2.6 meters, the shallowest cover ever encountered in a domestic shield tunneling project.

The Ningwu Railway is mainly for freight transport with a small amount of passenger transport. It is important infrastructure for enhancing freight capacity in the eastern section of the Yangtze River Economic Belt and an important component of the railway corridor along the Yangtze River. The Ningwu Railway capacity expansion and renovation project starts in the north at Nanjing East Marshalling Station (exclusive) and runs through Qixia District, Qinhuai District, Yuhuatai District and Jiangning District of Nanjing into Ma'anshan City, Anhui Province, then through Dangtu County into Wuhu City, and ends at Wuhu East Station (exclusive).

After reconstruction, the line will have a total length of 102.2 kilometers. The section from Cangbomen Station to Guxiong Station in the urban area of Nanjing is a newly built outer bypass realignment project with a length of 29.7 kilometers; the remaining sections will undergo electrification capacity expansion and renovation, with the main line of the reconstructed section measuring 72.48 kilometers. Once the project is completed and put into operation, it will further optimize the regional railway network layout and is of great significance for implementing the concept of "ecological priority and green development," accelerating the upgrading and adjustment of the industrial structure in areas along the line, optimizing the spatial layout of urbanization, and enhancing the flexibility of the railway network.