A train of Jinan Metro Line 4 runs in a trial operation in Jinan, east China's Shandong Province, on Aug. 31, 2025. Jinan Metro Line 4 started trial operation on Sunday. The metro line is laid along Jinan's east-west traffic artery, with a total length of about 40 kilometers. (Xinhua/Xu Suhui)

Staff members work on a subway train of Jinan Metro Line 4 in Jinan, east China's Shandong Province, on Aug. 31, 2025. Jinan Metro Line 4 started trial operation on Sunday. The metro line is laid along Jinan's east-west traffic artery, with a total length of about 40 kilometers. (Xinhua/Xu Suhui)

Citizens and journalists visit a subway train at a station of Jinan Metro Line 4 in Jinan, east China's Shandong Province, on Aug. 31, 2025. Jinan Metro Line 4 started trial operation on Sunday. The metro line is laid along Jinan's east-west traffic artery, with a total length of about 40 kilometers. (Xinhua/Xu Suhui)

A staff member works on a subway train of Jinan Metro Line 4 in Jinan, east China's Shandong Province, on Aug. 31, 2025. Jinan Metro Line 4 started trial operation on Sunday. The metro line is laid along Jinan's east-west traffic artery, with a total length of about 40 kilometers. (Xinhua/Xu Suhui)