A passenger information system, or passenger information display system, is an automated system for supplying users of public transport with information about the nature and the state of a public transport service through visual, voice or other media. It is also known as a customer information system or an operational information system. Among the information provided by such systems, a distinction can be drawn between: Static or schedule information, which changes only occasionally and is typically used for journey planning prior to departure. Real-time information, derived from automatic vehicle location systems and changes continuously as a result of real-world events, which is typically used during the course of a journey (primarily how close the service is running to time and when it is due at a stop, as well as incidents that affect service operations, platform changes, etc.). Static information has traditionally been made available in printed form though route network maps and timetable booklets at transit stations. However, most transit operators now also use integrated passenger information systems that provide either schedule-based information through a journey planner application or schedule-based information in combination with real-time information. Real-time information is an advance on schedule-only information, which recognises the fact that public transport services do not always operate exactly according to the published timetable. By providing real—time information to travellers, they are better able to conduct their journey confidently, including taking any necessary steps in the event of delays. That helps to encourage greater use of public transport, which for many countries is a political goal. Real-time information is provided to passengers in a number of different ways, including mobile phone applications, platform-level signage, and automated public address systems. It may include both predictions about arrival and departure times, as well as information on the nature and the cause of disruptions. Issues with passenger information provision There are four principal considerations for the provision of passenger information (static or real time): Data availability. Information can be provided only if it is available, and collecting information can be resource-intensive. Also, there may be difficulties with co-ordinating data sharing between multiple organisations. Data accuracy. Collecting information is error-prone. Also, prediction algorithms are not perfect and so real-time announcements may be in error. Getting information to the passenger. A variety of dissemination mechanisms may be used, but it is not always easy to ensure that the correct information reaches the passenger when it is