Metro Railways in India are rapid transit systems, operating since 1984. They started with the introduction of Kolkata Metro Railway System in Kolkata. Metro Railways were then constructed in other metropolitan cities of India. Delhi Metro, Rapid Metro Rail Gurgaon, Jaipur Metro and Chennai Mass Rapid Transit System are the fastest developing metro railway systems in India. Some of the metro railways in India are described below.
Kolkata Metro Railway System in India
Kolkata Metro serves the city of Kolkata, South 24 Parganas District and North 24 Parganas District in the Indian state of West Bengal. It is the first underground metro railway system in India, which opened for commercial services in 1984. The network consists of one operational line. It is the 17th railway zone of the Indian Railways.
Delhi Metro Railway System in India
Delhi Metro serves 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 both in terms of length and number of stations. A member of the Nova Group of Metros, Delhi Metro consists of five color-coded regular lines and the faster airport express line, with a total length of about 213 kilometers (132 mi). Delhi Metro serves 160 railway stations, including 6 stations on airport express line.
Namma Metro Railway System in India
Namma Metro, also known as Bangalore Metro or Bengaluru Metro serves the capital city of Karnataka namely, Bengaluru. The agency responsible for its construction is Bangalore Metro Rail Corporation Limited. It is a joint venture of the Government of India and the Government of Karnataka.
Rapid Metro Rail Gurgaon in India
Rapid Metro Rail Gurgaon serves the city of Gurgaon. It is linked with the Delhi Metro system`s Yellow Line at Sikandarpur. Built and operated by Rapid Metrorail Gurgaon Limited (RMGL), the system is India`s first fully privately financed metro.
Jaipur Metro Railway System in India
Jaipur Metro serves the city of Jaipur. Its construction started on 13th of November, 2010 and was completed in 2014. This metro has been constructed on the mostly elevated part of the first line called Phase 1A, comprising 9.63 kilometers of route from Mansarovar to Chandpole Bazaar. Jaipur Metro Railway System"s commercial run was delayed from early 2014 to December, 2014 and then to April, 2015. After receiving safety clearance from Commissioner of Metro Rail Safety (CMRS) in May, 2015, Jaipur Metro began commercial service on 3rd of June, 2015. Jaipur Metro Railway System is India`s sixth metro rail system. It is considered to be one of the fastest built metro systems in India. 
Chennai Metro Railway System in India
Chennai Metro serves Chennai in Tamil Nadu. The first line of Phase 1 has been partially completed and is open for public service. About 55 percent of the corridors in Phase I is underground, with the remaining corridors are elevated.
Mumbai Metro Railway System in India
Mumbai Metro serves the city of Mumbai. The introduction of this metro aimed at reducing traffic congestion in the city and supplementing the overcrowded Mumbai Suburban Railway network.
Metro Rail Lines in India
Metro Rail lines in India are composed of both broad gauge and standard gauge. The projects like the Delhi Metro used broad gauge for the earliest lines but many other projects in India are on standard gauge. This is because the rolling stock imported from Europe is on standard gauge.