Staff workers work at the construction site of a Yellow River tunnel in Jinan, east China's Shandong Province, May 9, 2025. A shield machine of the south line of the Yellow River tunnel started boring in Jinan on Friday, with an excavation diameter of 15.06 meters.

The Yellow River tunnel has a total length of 3,888 meters, with 3,252 meters to be excavated using a shield machine. It is designed as a six-lane, bidirectional highway with a speed limit of 60 km/h. (Xinhua/Xu Suhui)

This photo shows "Qihang," a tunnel boring machine deployed for the construction of a Yellow River tunnel in Jinan, east China's Shandong Province, May 9, 2025. A shield machine of the south line of the Yellow River tunnel started boring in Jinan on Friday, with an excavation diameter of 15.06 meters.

The Yellow River tunnel has a total length of 3,888 meters, with 3,252 meters to be excavated using a shield machine. It is designed as a six-lane, bidirectional highway with a speed limit of 60 km/h. (Xinhua/Xu Suhui)

Staff workers work at the construction site of a Yellow River tunnel in Jinan, east China's Shandong Province, May 9, 2025. A shield machine of the south line of the Yellow River tunnel started boring in Jinan on Friday, with an excavation diameter of 15.06 meters.

The Yellow River tunnel has a total length of 3,888 meters, with 3,252 meters to be excavated using a shield machine. It is designed as a six-lane, bidirectional highway with a speed limit of 60 km/h. (Xinhua/Xu Suhui)

Technical staff conduct inspection inside "Qihang," a tunnel boring machine deployed for the construction of a Yellow River tunnel in Jinan, east China's Shandong Province, May 9, 2025. A shield machine of the south line of the Yellow River tunnel started boring in Jinan on Friday, with an excavation diameter of 15.06 meters.

The Yellow River tunnel has a total length of 3,888 meters, with 3,252 meters to be excavated using a shield machine. It is designed as a six-lane, bidirectional highway with a speed limit of 60 km/h. (Xinhua/Xu Suhui)

Technical staff conduct inspection inside "Qihang," a tunnel boring machine deployed for the construction of a Yellow River tunnel in Jinan, east China's Shandong Province, May 9, 2025. A shield machine of the south line of the Yellow River tunnel started boring in Jinan on Friday, with an excavation diameter of 15.06 meters.

The Yellow River tunnel has a total length of 3,888 meters, with 3,252 meters to be excavated using a shield machine. It is designed as a six-lane, bidirectional highway with a speed limit of 60 km/h. (Xinhua/Xu Suhui)

Technical staff conduct inspection inside "Qihang," a tunnel boring machine deployed for the construction of a Yellow River tunnel in Jinan, east China's Shandong Province, May 9, 2025. A shield machine of the south line of the Yellow River tunnel started boring in Jinan on Friday, with an excavation diameter of 15.06 meters.

The Yellow River tunnel has a total length of 3,888 meters, with 3,252 meters to be excavated using a shield machine. It is designed as a six-lane, bidirectional highway with a speed limit of 60 km/h. (Xinhua/Xu Suhui)