Public display at terminals and stops
The most common method of providing passenger information at transport stops and terminals is through the use of overhead LED dot matrix displays. The information provided on these signs usually includes service departure times and destination points, route numbers or platform number and estimated arrival times at the stop. As these signs display real-time information they require connection to the AVL system and regular updates. Connections are provided wirelessly either directly from the AVL system on vehicles using the vehicle radio system, or from the vehicle via the operations control centre radio system. The roadside display units have inbuilt receivers through which location information is obtained and they often have inbuilt intelligence so that in situations where there is a failure in communications, operations can continue using a predefined timetable as a back-up.
Other forms of displays include LCD screen displays and plasma screen displays. LCD and plasma screen displays have an advantage over LED display in that they can display still images and video in addition to service information, which is particularly suitable for advertising purposes. LED, LCD and plasma screens can all be used in outdoor applications and operate reasonably well under all light conditions. In terms of large scale sign provision, LED displays are lower cost and may present a better option, although LCD and plasma costs have fallen substantially and the additional advertising potential may offset any initial cost differences. In addition to this, LCD and plasma screens tend to have a longer lifespan in all-weather conditions and therefore may present better value over time. Power consumption is also a significant factor and LED displays consume considerably less energy than the others, while LCD displays consume approximately 40% less than plasma. Combination LED LCD displays are becoming increasingly popular also, these perform better than plasma and LCD visually and are also more energy efficient, however they are more expensive a not yet suitable for such applications.
- Traveller information
Benefits and cautions
Overhead RTPI display can represent a substantial expense to operators in terms of the actual display units themselves and the complex AVL systems required to support them. They can also take a long time to implement. Despite this they are a useful customer service tool which provides passengers with the exact arrival times of services and early warning of service disruptions, both of which provide peace of mind and allow passengers to make arrangements in good time. In choosing which type of display to use, cost, visual performance and energy consumption are all major considerations.
Relevant case studies
Dublin, Florence, Izmir, Johannesburg, Mysore, Zurich