They provide visual/ and or audio announcements on transit vehicles. Generally announcements include next stop, major cross road, time and date, transfer point, major road crossing, and destination information. Electronic signs, video displays and annunciation systems constitute the In-vehicle transit information systems.
Bus stop announcements are required by the Americans with Disabilities Act (ADA) and are most often an operator’s responsibility. Automated annunciation systems relieves the
vehicle operator of that responsibility by announcing stops, transfer possibilities, and points of interest automatically based on the vehicle’s location, route, and direction of travel. Although these systems are primarily motivated by support for the disabled, they are also helpful for those unfamiliar with a route, when the bus is crowded, and when it is difficult to see outside the vehicle.
Visual messages of the announcements are also possible through the use of electronic messaging signs placed at one or more locations on the bus. These signs are obviously helpful for those users that are hearing-impaired.
Video displays are used to share important information regarding the time-tables, live delay information in case of problem on the line, alternative routes and safety information. These systems can visually show the bus as it travels along the route in real-time. Video displays may include other transit-related information, advertisements, or provide entertainment for the passengers.