On the afternoon of December 24, at the construction site of Section 3 in front of the station of the Shangyuanmen river-crossing passage, multiple large machines such as pile drivers were continuously operating. Drill bits bored into the ground with a steady roar, and mud slowly gushed out along the boreholes. Construction workers moved back and forth conducting inspections and debugging equipment, presenting an orderly scene of construction progress.

As Nanjing's first high-speed railway tunnel crossing the Yangtze River, the Shangyuanmen river-crossing passage has entered the substantive construction stage, with the Jiangnan and Jiangbei sections advancing in an orderly and synchronized manner. Among them, pile foundation construction at the Jiangbei shield launching section is proceeding steadily, laying the foundation for subsequent foundation pit excavation and shield machine launching.

This location is the key 'throat' connecting Nanjing's main urban area with the Jiangbei region, and is also the tunnel entry section of the Jiangbei section of the Shangyuanmen river-crossing passage. In the future, after the railway leads out from the newly built Nanjing North Station, it will transition from ground level to the underground tunnel section here, cross the Yangtze River to reach Jiangnan, and finally connect to the intercity yard of Nanjing Station. Therefore, this section is also one of the core control projects of the Jiangbei section of the Shangyuanmen river-crossing passage.

The Shangyuanmen river-crossing passage project has a total line length of approximately 20.4 kilometers, of which the tunnel section is about 14 kilometers long, designed as a single-tube, double-track high-speed railway tunnel. The line starts from the Ninghuai Intercity Yard of Nanjing North Station, passes through Pusi Road and Puyi Road to the Yangtze River bank, then turns southeast, passes beneath the Yangtze River, and is introduced into the intercity yard of Nanjing Station. Among them, Section 3 in front of the station, constructed by China Railway 16th Bureau Group, has a main line length of 7,472 meters, laid along Pusi Road and Puzhu Road. It must successively pass beneath multiple structures including the Pusi Interchange, the Ningtian Intercity Line S8, and the Qiaobei Sewage Treatment Plant, and finally achieve precise underground docking with the shield machine of the Jiangnan section in the tidal flat area on the north bank of the Yangtze River.

This section of the project is mainly a shield tunnel section, with a total length of 6,932 meters. Construction is extremely difficult and features five prominent characteristics: 'large, long, deep, risky, and precise.' Among them, the two core difficulties of 'risky' and 'precise' are as follows: the shield tunnel section must pass through multiple groups of highly sensitive existing buildings and structures, imposing extremely high requirements on settlement control and construction precision; at the same time, the entire tunnel section of the river-crossing passage will be constructed by shield machines advancing toward each other from Jiangnan and Jiangbei, making precision control and risk prevention and control throughout the entire process extremely difficult.