The Kolkata Suburban Railway is a suburban rail system serving the Kolkata metropolitan area and its surroundings in India. It is the largest suburban railway network in the country with the highest number of stations. It is also the 7th largest suburban rail system in the world. There are five main lines and nineteen branch lines. The suburban railway operates more than 1,500 services, carrying 3.5 million people daily and 1.2 billion people every year. It runs from 03:00 am until 02:00 am and the fares range from Rs.5 to Rs.25. The system uses 25 kV 50 Hz AC power supply and runs on 5 ft 6 in (1,676 mm) broad gauge track. It has interchange stations with the Kolkata Metro at various locations.