Nanjing currently operates 9 lines: line 1, line 2, line 3, line 4, line 10, line S1, line S3, line S8 and line S9. The Nanjing Metro is expected to develop into 17 metros and 6 intercity express lines by 2020, which will further shorten the distance between Nanjing and the surrounding small and medium-sized cities and counties.