Kolkata Suburban Railway is huge and extensive and covers large areas in hinterland with Sealdah being an important suburban rail terminal. The suburban railway or urban or metropolitan is a type of transportation that uses rail lines eg the so-called loops for routing of convoys in order to ensure a fast moving mass of people in very large cities or fractionated in neighborhoods distant from each other or between them and the urban centers of the district.
In Switzerland these services are referred to as lines or networks expeditious expeditious, using expressions of obvious derivation German Schnellbahn. In addition, the trains to suburban or metropolitan service must be between the strengths of the acceleration rather than top speed. The infrastructure used by suburban rail services can also be used by other types of traffic freight trains, regional trains, long-distance as opposed to the infrastructure used by the underground classic which are increasingly isolated from any other network station.
Infrastructure can not be used by the metropolitan level crossings as opposed to the infrastructure used by suburban rail services, urban or metropolitan. Frequency, cost and travel time may vary depending on the distance and size of the network, which is used to connect the more distant areas of a large metropolitan area in quickly and easily: note that a suburban railway only connects areas that are relatively close together, otherwise it would be a character train regional. The races that perform service on a suburban railway line generally carried out all the stops. On the same lines may run even trains to other types of rail services, such as regional , but do not carry out all the stops.
The large and vast metropolis often adopt this solution also for mass transport between quarters away from the center.
Generally each city adopts a specific symbol and identifies the lines with a number. The suburban lines are generally reported in the maps of the city's public transport fit perfectly. The suburban rail services are then integrated from the point of view of tariff and other means of public transport: road, tram, underground.
Each city operates its own services with different characteristics depending on the needs of transport, some examples of such service or similar are the RER in Paris , the Overground London , the Cercanía Spanish eg Cercanías Barcelona, the S- Bahn city of the German, Austrian and Swiss or HÉV, suburban rail system of transportation of Budapest.