Rail travel is one of the predominant modes of transportation in India, and the entire railway network is centralised under a single, government-owned organisation known as the Indian Railways. One of the largest railway networks in the world, the Indian railways covers the entire length and breadth of the country, and transports a very high volume of passenger and freight traffic on a daily and monthly basis. The Indian rail services extend even to the neighbouring countries of Nepal, Pakistan and Bangladesh, on a limited basis. The entire rail network is divided into a number of zones, and these zones are, in turn, classified into sub-divisions. Freight traffic is the biggest contributor to the revenue earned by the railways, while passenger traffic is largely a loss-making division. This is because passenger ticket fares are kept deliberately low to make rail transport affordable for all. Trains are classified based on their average speeds, and some of the categories include express trains, mail trains and passenger trains. Recent additions include the rapid transit systems or the Metro railway networks in certain cities such as Kolkata, Delhi, Chennai and Bangalore. Hide this