At 8 AM on the 21st, two shield machines launched from Tangyunhai Station: one heading south to the left line interval of Machi Station (hereinafter referred to as the "Tang-Ma Interval"), and the other heading north to the right line interval of Julong Avenue Station (hereinafter referred to as the "Ju-Tang Interval").

The Tang-Ma Interval, with a single-line length of 4.92 km, is the longest shield-driven interval on the north extension of Line 7 (Qianchuan Line) and one of the key nodes of the project. After departing from Tangyunhai Station, the line runs along the shoreline of Xinjiao Lake to the Wuhan-Xiaogan Intercity Railway and passes beneath its viaduct. North of the Second Airport Expressway, No. 1 intermediate ventilation shaft is set up. After passing under the roadbed of the Second Airport Expressway and the Fu River, No. 2 ventilation shaft is set up south of the Dongxihu Embankment. The line then turns into the central green belt of Huanhu Middle Road and reaches Machi Station.

The Tang-Ma Interval involves multiple challenges: first, crossing a karst development area, which makes shield attitude control difficult; second, passing beneath major structures and buildings, including the Wuhan-Xiaogan Intercity Railway and the Second Airport Expressway, with high requirements for settlement control; third, crossing beneath the Fu River. The project department has made precise calculations to complete the tunneling before the peak flood season in July and August, minimizing risks.

The Ju-Tang Interval has a total single-line length of 2.23 km. The shield machine launches from Tangyunhai Station, turns to the northeast, and runs straight along Yunlong Road to Julong Avenue Station. The shield passes beneath the roadbed of the Airport Expressway and then beneath the existing Line 2 before reaching Julong Avenue Station. The interval has three cross passages, including a ventilation shaft (also serving as a cross passage) on the west side of the Airport Expressway, and a combined cross passage and pump room at the lowest point of the interval.

The shield construction in the Ju-Tang Interval will face three difficulties: first, crossing numerous structures and buildings, including underpassing the Airport Expressway and the existing Metro Line 2, and side-crossing many buildings, requiring strict control of structure settlement; according to geological surveys, drilling has revealed 145 karst caves of various sizes within the shield interval, requiring strict quality control of karst grouting reinforcement; the shield tunnel passes through moderately weathered marl, limestone, cataclastic siliceous dolomite, and moderately weathered dolomite, with high rock strength. The saturated uniaxial compressive strength of moderately weathered siliceous dolomite is up to 80 MPa, making it a hard nut to crack.

Up to now, the main structures of Baitai Road Station and Tangyunhai Station on the north extension of Line 7 (Qianchuan Line) have been completed. Julong Avenue Station, Tenglong Avenue Station, and Hengdian Station are under main structure construction. Five stations—Machi Station, Tianyang Road Station, Linkong North Road Station, Beiche Base Station, and Huangpi Square Station—are undergoing enclosure structure and pile foundation construction. Seven elevated intervals have started construction. Meanwhile, of the 15 single-line shield intervals, the left and right lines from Baitai Road Station to Beiche Base Station have been completed, and the interval from Baitai Road Station to Huangpi Square Station is under tunneling. The depot has been mobilized and is undergoing pile foundation construction.

The north extension of Line 7 (Qianchuan Line) is a line in the fourth phase of Wuhan's rail transit construction plan. The project starts at Huangpi Square Station and ends at Yuanboyuan North Station (exclusive) of the first phase of Line 7, passing through Huangpi Qianchuan urban area, Beiche Base, Linkong Economic Development Zone, Panlongcheng, and Dongxihu District. The total length is 36.47 km, including 22.6 km of elevated section, 1.08 km of transition section, and 12.79 km of underground section. There are 11 stations, including 5 elevated stations (1 reserved) and 6 underground stations.