Passengers take Chongqing Rail Transit Line 18 in southwest China's Chongqing Municipality, Dec. 28, 2023. Chongqing Rail Transit (CRT) Line 18, which is 29 kilometers long and has 19 stations, officially started initial operation on Thursday. So far, a total of 13 rail transit lines are in operation in the city with an operating length reaching 538 kilometers. (Xinhua/Wang Quanchao)