Trains are one of most of widely used modes of transportation through out the world. Though laying railway tracks and starting a train service requires a large investment initially, once the service is in operation, the running cost is comparatively low and a large number of people can be transported at a time.
Trains can be classified into 2 main categories:
1. Short distance trains: these are trains operating in cities and their suburbs. Most of the travelers are regular commuters who board the train in the morning to reach their office and again board the train in the evening to reach their home. In most cities, these trains operate on electricity. They cover a distance of about 100 kilometers or more within a couple of hours, with frequent stops at the stations. The stations are usually less than 5 kilometers apart. Many crowded large cities have an underground railway system to save space. The trains are designed to carry a large number of passengers and usually close to their scheduled time.
2. Long distance trains : these trains operate between cities in the same state or different state. The journey can take anything between a few hours to a few days. For overnight journeys, there is a provision for sleeping. Compared to short distance trains, these trains are less crowded, though there may be little standing space during holiday season. The fast or express trains halt only at a few stations, while the normal trains have may halts where passengers can board or leave the train.