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Intelligent transport system using GIS
2. Package Development
2.1 Mechanism
Developing Advanced Traveler Information System (ATIS) in Geographic Information System (GIS) is main objective of current project. In this system shortest path, closest facility and city bus routes were included. Besides these features location wise information and inter city traveler information like bus, train and airways timing are also included. Mechanism involved in the development of package is described in following sections.
2.1.1 Shortest path
Route planning is a process that helps vehicle drivers to plan a route prior to or during a journey. It is widely recognized as a fundamental issue in the field of transportation. A variety of route optimization criteria or planning criteria may be used in route planning. The quality of a route depends on many factors such as distance, travel time, travel speed and number of turns. These all factors all can be referred as travel cost. Some drivers may prefer the shortest path based on distance and some prefer based on travel time [11].
The route selection criteria can be either fixed by a design or implemented via a selectable user interface. In the current project route selection is via user interface. In the optimization of the travel distance (road segment length), distance was stored in digital data base and the route planning algorithm was used. In the optimization of travel time, road segment length and speed limit on that road are stored in digital data base and travel time was calculated (distance/speed limit). The calculated travel time was used as travel cost in the performance of path optimization.
2.1.2 Closest facility
In the closest facility problem route length and travel time (drive time) were considered as travel costs. Different facilities like hospitals, bus stations, and tourist places were taken as themes in the project. Closest facility algorithm calculates all the routes from selected origin to facilities based on travel cost. It compares travel costs of these routes and gives one optimal route as output [1].
2.1.3 City bus routes
City buses with their numbers were stored in a data base in a compressed format because on one road segment there will be more than one bus. A search algorithm was used to find bus service number from selected origin and destination. According to bus number, road segments on the map were selected and highlighted with different color. The schematic flow chart of the package is shown as Fig 1.
2.3 Source Program
The source program for this package has been written in Avenue programming language. Avenue is object-oriented and scripting language for ArcView GIS. Customization of the package was done in Avenue. The source code was divided into many numbers of scripts because in Avenue language functions or procedures are not available. Each script is used for a specified purpose.