1. Introduction
The current fast pace of life around the globe demands an effective, fast and reliable Public Transportation System. This system has become indispensable for the people. It is just not enough to have an efficient, effectual or an unswerving Public Transportation System, but in a huge city like Chennai it is also imperative that the commuter knows which bus he should take to his destination. So, the need of the hour is an Information system – A Public Transport Information System. The tech savvy public, have become heavily dependent on such systems, which would allow access to information at the click of a mouse. It puts an end to the various hassles which commuters face en route to a new place.
Not every one of us may know almost all the bus routes that are available, but, if a necessity arises to travel to a new place, it is customary that someone in the boarding place comes to the rescue or the guide map guides us to the destination. Hence it augurs well for the development of a Public Transport Information System, which would provide the following,
- Timings/frequency of the various buses,
- Buses connecting various places of interest to the commuters, from their place of boarding,
- Buses connecting places of tourist interest from the commuters’ boarding place, and
- Shortest possible route for the commuter with respect to time and/or distance.
2. Study Area Description and Data used:
The study area (routes) taken for this pilot project was (were) from Vadapalani bus terminus to five termini. They were Parys, Vallalar Nagar, Beasant Nagar, Triplicane and Foreshore estate. The routes were so chosen that they tested the algorithm for its fullest capabilities and represented all the needs of the information system.
Table 1: Bus routes selected for the project
| S.NO. | BUS NO. | FROM-TO |
| 1 | 5E | Vadapalani --Beasant Nagar |
| 2 | 12B | Vadapalani – Foreshore Estate |
| 3 | 17, 17M (Cut) & 17C | Vadapalani – Parys |
| 4 | 25 | Vadapalani – Triplicane |
| 5 | 37 | Vadapalani – Vallalar Nagar |
The data used for the pilot study was the TTK Chennai City guide map, at a scale of 1:25,000. The map was scanned using an A0 scanner for the purpose of onscreen digitization. A handheld GPS, Trimble Scout guide model was used for the acquisition of the control points- to geocode the scanned map, and the co-ordinates of each bus stop and the termini along the routes.
3. Methodology
The study “routes” for the project were those from the Vadapalani bus terminus in West Chennai. This terminus served as the nodal terminus from which routes to five other termini were selected. The hub of the project is the development of the algorithm to obtain the shortest or optimal route of travel for the commuter. The eventual outcome from the algorithm is a graphical output in the form of a map for the information required.
3.1 Fieldwork
The data required by an information system has to be inexhaustible but with its own limitations. Hence, the data collected for this purpose was extensive. First of all, the various bus stops on each of the five routes were identified. This was done, by traveling along each of the five routes. Both the to and fro routes had to be traversed as the bus routes in both the cases differed due to one way roads. Other information collected were the one or two nature of the road, important landmarks for the bus stops and the total time for the journey (the latter may vary depending on the hour of the day). The information collected was then stored in the database and used for further analysis.
Any GIS demands known and well-defined coordinates without which no analysis can proceed. Keeping this fact in mind, the authors collected the geographical coordinates of seven precise control points using the hand-held Global Positioning System (GPS). In addition, the GPS was used to collect the geographical coordinates of individual bus stops for each of the five routes. Where there was much obstruction at the bus stop, a nearby spot was chosen and the corresponding geographical coordinates were recorded.
The fieldwork was followed by on screen digitization of the road map of Chennai city. The TTK Chennai city guide map was made use of from which the roads were extracted. The road map was scanned and on screen, digitization performed using ArcView. Then the road theme was transformed to GPS co-ordinates with the help of control point data taken using the hand-held GPS. Then bus stop point data was extracted using the road theme.
3.2 Algorithm
Optimal Routing is the process of delineating the best route to get from one location to another. The “best route” could be the shortest, the quickest or the most aesthetic, depending on the GIS user’s preference for defining “best”. In our case, we define the “best” route, which takes the shortest time with minimum number of transit points.
As already stated, the algorithm is the essence of the project. Using the algorithm, which is being written in Arc Avenue the bus routes are analyzed for
- Optimal route of the available routes between the point of boarding and destination.
- Comparison of direct routes with transit routes for evaluating the travel time of the optimal route.
- Comparison of time of travel with frequency and timing of the buses to arrive at the optimal route.