In rail transport, the paid area is a dedicated "inner" zone in a railway station sealed by barriers. A system using paid areas is often called fare control. Passengers are allowed to enter or exit only through a faregate. A paid area usually exists in rapid transit railway stations for separating the train platform from the station exit, assuring a passenger has paid or prepaid before reaching the platform and using any transport service. Such design requires a well organized railway station layout.
The paid area is similar in concept to the airside at an airport. However in most cases entrance to the paid area requires only a valid ticket. The exception is in international rail travel, where passengers must also pass through immigration control and customs to enter the paid area. Examples include the Eurostar international platforms at St. Pancras railway station and Gare du Nord or Tanjong Pagar railway station in Singapore, where the only departures are to neighboring Malaysia.
A platform ticket allows non-travelers access to the paid area of a station to greet friends and family members or to assist them with their luggage without having to have a ticket for a journey. These are generally available only at major terminal stations.