 The Delhi Metro is a metro system serving Delhi and its satellite cities of Faridabad , Gurgaon , Noida and Ghaziabad in National Capital Region in India . Delhi Metro is the world 's 12th largest metro system in terms of both length and number of stations . , the network consists of five colour @-@ coded regular lines and the faster Airport Express line , with a total length of 213 kilometres ( 132 mi ) serving 160 stations ( including 6 on Airport Express line ) . The system has a mix of underground , at @-@ grade , and elevated stations using both broad @-@ gauge and standard @-@ gauge . The metro has an average daily ridership of 2 @.@ 4 million passengers , and , as of August 2010 , had already carried over 1 @.@ 25 billion passengers since its <unk> named second best metro in world 
