Passengers must buy and validate a ticket immediately after boarding a vehicle, or before entering a metro station's paid area. There are uniformed and plainclothes fare inspectors who randomly check passengers' tickets within the paid area; they are equipped with an inspection badge or carrier ID.
Passengers must purchase and validate a ticket immediately upon boarding a vehicle, or before entering a metro station's paid area.  Fare inspectors randomly check passengers' tickets within the paid area; they are equipped with identification badges or carriers.