On January 5, the right-line large-chainage section of the Jinsong 3rd Road Station—Jinsong 4th Road Station interval on Qingdao Metro Line 4, constructed by China Railway 17th Bureau Group Co., Ltd., was successfully holed through. This marks the completion of another major milestone in Section 06 of Qingdao Metro Line 4, with the entire line entering a new construction phase and formally moving into secondary lining construction.

The Jinsong 3rd Road Station—Jinsong 4th Road Station interval (abbreviated as the Sansi Interval) is the 13th main-line interval of Qingdao Metro Line 4, with a total main-line length of 548 meters and a right-line large-chainage length of 171 meters. The tunnel body of the Sansi Interval mainly passes through strongly weathered granite, with a small portion passing through moderately and slightly weathered granite, and crosses five fault fracture zones. The surrounding rock is Grade V and VI, the geological conditions are poor, and the geological risk is relatively high.

Qingdao Metro Group and Qingdao Metro Line 4 Company organized the construction unit China Railway 17th Bureau to repeatedly convene expert demonstrations to optimize the construction plan and ensure safe and orderly construction. During construction, a special working group was established to efficiently allocate personnel, materials, and machinery; in terms of staffing, construction teams with rich experience in metro tunnel construction were selected; in project quality control, the three-inspection system of self-inspection, mutual inspection, and handover inspection for each process was strictly implemented; in project safety assurance, a safety and quality team was established to conduct pre-job safety and quality training and technical briefings for construction teams, regularly organize safety and quality inspections, solve problems on site, and hold people accountable to the end.

Through meticulous organization in staffing, quality control, safety assurance, and other aspects, the right-line large-chainage section of the Sansi Interval on Qingdao Metro Line 4 was successfully holed through, marking that the construction of Qingdao Metro Line 4 has reached a new level.