A ticket controller is a person who randomly checks tickets on public transport in systems where one can enter the vehicle without being checked. The system works as follows:
- passenger purchases a ticket
- passenger enters the vehicle and validates the ticket. Sometimes validation is performed when entering platform (Berlin metro)
- a controller randomly enters the vehicle and checks tickets. A fine is imposed if a person without a valid ticket is found.
Statistics: in Poznan, Poland the rate of free-riders varies from 4 to 10%.