A passenger-carrying vehicle (for example a bus) in a passenger transport system is equipped with a ticket reader (18) capable of optically reading information printed on a ticket (10) in bar-code and determining whether or not the ticket is valid. A ticket-printer (16) is provided for issuing bar-coded tickets, and both the reader (18) and the printer (16) are microprocessor-based and associated with a memory (14). Fare-table data is stored in the memory (14a), for reference by the ticket-issuing means, data is stored in the memory (14b) for reference by the ticket-checking means, and both the issuing means and the checking means can communicate information to the memory (14c) and (14d) to enable data concerning tickets handled to be stored for subsequent retrieval for management purposes.