Urban rail transit systems in India mostly use standard gauge tracks. These systems are operated by metro/tram rail corporations which are independent of Indian Railways. Trams in Kolkata, the only remaining tram service in the country, uses standard gauge tracks. Line 1 of the Kolkata Metro and Delhi Metro use the same broad gauge tracks as main-line railways. All other metro linesconstructed, under construction and futureuse standard gauge tracks. Metro trains operate in Delhi, Bangalore, Chennai, Mumbai, Hyderabad, Jaipur, Kochi, Nagpur, Ahmedabad and Lucknow. Gurgaon has a Metro system operated by a private organisation. Metro tracks are being constructed or planned in all million-plus cities in the country.