The new lines have brought the total length of Chengdu's far-reaching metro system to 558 km.
Line 6, the first phases of lines 8, 9 and 17, as well as the eastern section of Line 18 have been opened.
Line 18 links Chengdu's city proper with its new airport, the Chengdu Tianfu International Airport, which is slated to begin operations next year.
An automated train system has been deployed on Line 9. Trains on the line can automatically run, stop, turn on, and carry out inspections.
The Chengdu Metro launched its first line, Line 1, in 2010. So far, it has transported more than 6 billion passengers, with the average daily number of passengers exceeding 4 million.