Line 4 of the Beijing Subway  is the 9th subway line in Beijing's mass transit network. It entered into operation on September 28, 2009, and runs from north to south, parallel and to the west of Line 5, through Haidian, Xicheng, Xuanwu and Fengtai Districts in the western half of the city. It is 28.2 km long with 24 stations. Riding on this line starts from a fare of RMB(¥) 3.00 depending on the distance travelled. Line 4's color is  teal.