Have you ever thought

during the daily rush hour

suddenly

a train blocks the way

adding more "fire" to the already tense commute

How anxious would you feel at that moment!

Actually, such scenes

are staged every day along the Ningwu Railway in Nanjing, the "Ancient Capital of Six Dynasties"

However, this situation

is about to change!

On August 12, near Nanjing South Railway Station

at the construction site of the Nanjing South Tunnel project

undertaken by China Railway 14th Bureau

the cutterhead of the steel behemoth "Ningwu" slowly rotated

marking the official launch of the shield

and major progress in the capacity expansion and reconstruction project of the Ningwu Railway

has been achieved

Launch of the "Ningwu" shield machine

Li Hui, Vice Mayor of Nanjing, announced the launch of the shield. Wu Fengyuan, Deputy General Manager of China Railway Shanghai Group Co., Ltd., Zong Ren, Director of Nanjing Transportation Bureau, Dong Chuanxin, Commander of the Hefei Hub Command, Li Fangyi, District Mayor of Yuhuatai District, and other leaders attended the event. Zhou Changjin, General Manager of China Railway 14th Bureau, attended the event and delivered a speech.

Zhou Changjin delivers a speech at the launch event

In his speech, Zhou Changjin stated that China Railway 14th Bureau will thoroughly implement the construction philosophy of "ecological priority and green development", always uphold the core values of "professionalism, pragmatism, innovation, and win-win", fully leverage its construction, technical, management, and resource advantages in the field of large-diameter shields, and comprehensively carry out technological innovations such as smart construction sites, digital shields, intelligent construction, and monitoring and early warning, to ensure safe, fast, high-quality, and efficient construction, and strive to build a benchmark railway project.

Employee representatives from Nanjing Municipal Government, China Railway Shanghai Group Co., Ltd., Nanjing Transportation Bureau, Yuhuatai District, and project design, construction, and supervision units attended the event.

A nearly century-old railway divides Nanjing "in two"

and is about to be revitalized through "capacity expansion and relocation"

The predecessor of the Ningwu Railway is the Jiangnan Railway, first built in 1933 and put into operation in 1935. It runs from Nanjing to Wuhu with a total length of 125 kilometers. It is a national railway line undertaking important passenger and freight transport tasks in the Yangtze River Delta region and was once one of the busiest single-track railways in China.

However, with the development of Nanjing, the population has continued to gather, and the areas along the Ningwu Railway within the city have gradually transformed from farmland and wasteland into densely built-up urban development areas.

Schematic diagram of the urban section of the Ningwu Railway capacity expansion and reconstruction project in Nanjing

In particular, the section from Cangbomen to Guxiong is located in the central urban area of Nanjing. It not only "cuts" the city apart, but the areas adjacent to both sides of the railway have also become a vacuum for urban development and a difficult area for comprehensive governance, with unbalanced development on both sides of the railway.

At the same time, the Ningwu Railway also cuts across all urban roads on both sides, forming numerous level crossings that rely on traffic lights or manual control. This has caused serious obstruction and congestion for the daily travel of hundreds of thousands of residents along the line and for motor vehicle traffic.

Technicians start the shield machine

After years of research and evaluation, the Ningwu Railway capacity expansion and reconstruction project fully started at the end of 2022. After reconstruction, the line length is 102.2 kilometers, of which 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. After the bypass, multiple urban "dead-end roads" severed by the old Ningwu Railway will be connected, "stitching" the ground traffic together.

"Super long tunnel" moves the railway underground

Key shield technologies overcome the most difficult section

In the Cangbomen to Guxiong section of the Ningwu Railway located in the central urban area of Nanjing, the existing railway is relocated, and the Nanjing South Tunnel, about 14.4 kilometers long, is constructed by China Railway 14th Bureau. It is a controlling project for the entire line, a single-tube single-track tunnel with a design speed of 120 kilometers per hour.

The tunnel crosses Qinhuai District, Yuhuatai District, and Jiangning District of Nanjing, passing under trunk railways such as the Ning'an High-speed Railway, Beijing-Shanghai High-speed Railway, and Shanghai-Chengdu Railway, as well as major roads such as Ningdan Highway and Niushou Avenue. About 2.4 kilometers of the section is constructed by the shield method, which is a controlling node for the entire line.

Schematic diagram of the shield tunnel

The shield section of the tunnel starts from the Meixiang Road working shaft in Yuhuatai District, passes under Nonghua River, Airport Expressway, Qinhuai New River, and the existing Beijing-Shanghai High-speed Railway tunnel in Hanfu Mountain, crosses over Metro Line S1, and runs parallel to Metro Line S3 for a long distance. It features many water bodies and complex surface and underground environments.

China Railway 14th Bureau "tailor-made" an earth pressure balance shield machine, the "Ningwu", with an excavation diameter of 9.33 meters. It applies intelligent technologies such as a visual system for the excavation chamber and a shield tail brush wear detection system, which can effectively control shield construction risks and comprehensively improve tunneling efficiency.

At the same time, the section under the Qinhuai New River is a key risk control point, with the shallowest cover of only 2.6 meters, which is the shallowest cover encountered in domestic shield projects so far. The key technologies mastered by the construction team, such as micro-disturbance precise crossing, safe tunneling in special complex strata, and intelligent tunnel monitoring, can ensure "zero disturbance and zero intervention" during shield tunneling.

"Underground crossing" helps stitch urban space together

becoming another classic case of "railway + shield"

The Ningwu Railway in the urban area of Nanjing is relocated through "underground crossing" and other methods, which will accelerate the stitching of urban spaces severed by the existing railway.

Moreover, it will completely eliminate the safety risks of level crossings in the section, resolve a series of problems caused by the original line passing through the city, such as noise interference, pollution emissions, and traffic congestion, and unblock the urban development arteries.

Workers inspect equipment

After the entire Ningwu Railway capacity expansion and reconstruction 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 along the line, optimizing the spatial layout of urbanization, and enhancing the flexibility of the road network.