Global Positioning Systems (GPS) are now in use in many applications ranging from environmental research, route guidance, fleet management, automatic pilots, traffic travel-time surveys, and many more transportation related and geographical systems. Most of current GPS systems are designed using Geographical Information Systems (GIS). These systems allow the data collected by the GPS to be stored, manipulated and displayed with their spatial attributes. GIS packages usually incorporate some kind of database facilities, enabling the user to perform complex queries on the stored database.
This paper describes a public transport in-bus real-time passenger route information system based on a GPS. Basically, the system provides instant location information to the on-board passengers by flashing LEDs on a large wallmap corresponding to the bus stop positions on the route of a bus. One of the aims of this project was to increase the use of public transport. Providing better information to passengers would boost the use of public transport and help to ease the ever growing traffic congestion problems in big cities.
The system described receives the vehicle location information from a GPS every second. The output of he GPS is fed to the serial port of an on-board IBM compatible laptop computer (PC) for processing. The PC is pre-loaded with the co-ordinates of the bus-stops on the route of a bus. The PC calculates in real-time the distance between the bus-stops and the current location of the bus. The bus is then assumed to be at or near a bus-stop if this distance is less than a given constant. The LED corresponding to the current bus-stop is then flashed to indicate the current location of the bus.
The output from the system is a large non-intelligent wallmap, showing the bus routes in the area of interest. Small bright LEDs are fitted to the wallmap corresponding to the positions of the bus-stops on the current route. There were several reasons for using a wallmap instead of a graphical computer display unit. Perhaps the most important reason was the cost. Large computer displays are very costly compared to the costs of wallmaps. This cost is multiplied by many times if the system is to be used on many buses and on both the upper and the lower decks of a bus. Large displays are also bulky and heavy and can not easily be mounted at required positions on a bus. Wallmaps are light and can be designed in any shape and form to be mounted easily on a bus.
In general, the field trial results were satisfactory. Problems were encountered in areas with tall buildings. A GPS requires a minimum of three satellite data in order to estimate position. The satellite visibility was observed to fall below three at parts of the journey in the inner city areas where tall buildings obstructed the satellite view.
The system described is a very low cost in-bus public transport passenger route information system providing location information to the on-board passengers. The system should especially be useful on routes populated by tourists who are not familiar with the area and the bus routes.