A Framework for web GIS Based Computerized Traveler Information and Decision Support System for Metropolitan Cities in India Varun Singh Department of Civil Engineering Indian Institute of Technology Roorkee UA 247667, INDIA Phone: +91-98-371-34068 Fax: +91-1332-273560 vspcedce@iitr.ernet.in  Praveen Kumar Degrees in Civil Engineering Indian Institute of Technology Roorkee India UA 247667 Phone: +91-1332-285470 Fax: +91-1332-273560 pkaerfce@iitr.ernet.in  Dimitris Kotzinos Department of Computer Science University of Crete Heraklio, Crete 71110 Fax: +30-2810-393501 kotzino@csd.uoc.gr Abstract Due to spatial and temporal variations in roadway, traffic and weather conditions, travelers within cities are not generally conversant with prevailing roadway and traffic conditions. Advanced Traveler Information Systems (ATIS) aim at bridging this information gap by implementing computer science, communication and information technologies and management strategies to provide the pretrip and/or en-route information to the travelers about their travel options so as to influence their travel behavior about mode choice, time of travel, route choice or trip making. In this paper, the authors discuss a traveler information system, which relies on web based GIS and supports the concept and framework of ATIS by integrating traffic related (directly or indirectly) information from various sources. The proposed system called Computerized Traveler Information and Decision Support System (CTIDSS) will provide comprehensive pretrip traveler information with key functionalities like route planning, proximity analysis, itinerary planning etc. CTIDSS will incorporate unique characteristics, cover the broadest possible information space and promote mainstream access form the general public by making information available through various dissemination means like the internet, internet-enabled cell phones, etc 1. INTRODUCTION National and regional state transport authorities in India have been monitoring traffic and collecting traffic data as part of their traffic management strategies for many years, but generally they do not often share the collected information with travelers and when they do, it is provided as is i.e. without processing in order to finally provide value-added service to the public. Thus in the absence of comprehensive traveler information services, travelers traveling for specific purposes like social, business, recreational etc. in Indian metropolitan cities are not well informed about spatial and/or temporal variation of roadway, traffic stream characteristics and available socio-economic facilities like hospitals, offices, recreational facilities at the available nearby road network. Advanced Traveler Information Systems (ATIS), which are one of the types of ITS, can serve this need. ATIS assist travelers by providing them timely, accurate, reliable and relevant information about their travel options, so that they can take well-informed travel decisions and reach their destinations quickly and safely. The authors propose a web GIS based system for analyzing and disseminating pretrip traveler information for a typical metropolitan area (in this study in India but with the ambition to provide a rather universal approach), which carries real-time information handling capabilities. Authors call such a system as Computerized Traveler Information and Decision Support System (CTIDSS). Pre-trip systems inform travelers of traffic and transit conditions, so they can assess travel options before selecting a route, mode, departure time, or deciding whether to make the trip altogether. The proposed approach of implementing the CTIDSS as a web GIS based system has the following advantages:
It has been assumed that data from data acquisition and processing systems are available to CTIDSS in the form of relational database for further analysis and dissemination. These types of data are real time data pertaining to traffic conditions (vehicle speed limit, congestion level etc.) and incident conditions like road blockage, construction zone, bad road condition, accidents etc. and information regarding available transit facilities like timetables of bus, train and air services. Accumulating all this information allows the system to address the needs of various types of users among which are everyday vehicle drivers, pedestrians (walking), tourists and transit passengers. Key functionalities that CTIDSS is envisioned to provide will include route planning, proximity analysis, itinerary planning, yellow pages information, information about available public transit facilities, information regarding prevailing roadway and traffic conditions in typical metropolitan ambience. Some of these functionalities are brought along with the proposed use of a GIS as the building block of the overall system. Coupling that with real-time data provides the necessary value-added in order for such a system to be both useful and viable. Furthermore making it web based allows for seamless access from anywhere by anyone. CTIDSS will allow for different degrees of customization, giving the users and the administrators the ability to customize both the quantity and the quality of the information they want to receive. In the following sections, the authors discuss conceptual architecture, data requirements, functionalities offered and deployment scheme of the proposed system in detail. 3. DESCRIPTION OF PROPOSED SYSTEM-CTIDSS 3.1 Conceptual Architecture Conceptual architecture provides schematic representation of different components and information flow between different components of CTIDSS and it is independent of details of the implementation. The process of developing the conceputal architecture focuses on questions of what it the system will do which is termed as system analysis (Worboys and Duckham 2004). Broadly conceptual architecture of CTIDSS will comprise of three layers or tiers: Presentation Tier, Application Tier and Data Tier as shown in Figure 1. Following sections provides the brief details of these tiers. 3.1.1 Data tier The Data Tier will be concerned with storage and management of spatial information (along with associated attribute data) of road network topology of area and features of interest. Attributes for road network also include the temporal information that is varying throughout the day. Temporal information is the real-time information pertaining to prevailing traffic conditions (vehicle speed limit, congestion level etc.) and incident conditions like road blockage, construction zone, bad road condition, congested road, accidents etc. and information regarding schedule of operation of public transportation like Buses, Mass Rapid Transportation Systems (MRTS) etc. 3.1.2 Application tier Application Tier will be sandwiched between the Data Tier and the Presentation Tier and will form an important component of the CTIDSS conceptual architecture. The components in the Application Tier handle the requests of the user and process these requests on the data in the data tier to give a timely response. It will consist of the Web Server, Server Connectors and the Map Server. The Web Server will handle and transfer the clients’ requests that are subjected to geospatial analysis and processing on map server. The Web Server will also forward the response back to the requesting client. Server Connectors will provide communication link between Web Server and the Application Server, manage load-balancing i.e. optimizing requests from clients. Generally, a connector is either an Active X component, or a Java component. A Web Server can support multiple connectors; however a connector is associated with a single Web Server. The Map Server will process client requests handed to it by the Web Server. It will access the spatial data, performs geo-spatial analysis and renders web-ready map as vector or raster image. 3.1.3 Presentation tier The Presentation Tier will consist of the end-user application program that travelers will use to interact with CTIDSS. For CTIDSS, the end-user application program will be in the form of an interactive web interface website consisting of controls, links and ‘hot spots’ that will be accessed by the travelers using Internet browsers like Microsoft’s Internet Explorer, Netscape’s navigator etc. Browsers will be coupled with web plugins. Plugins or add-ons are the ActiveX controls or Java applets that run on browsers so as to publish map returned by map server after geospatial analysis and equip users to carry out basic geospatial events like map readout, feature selection, map zoom in/zoom, linear and area measurement. For more advanced geospatial analysis like shortest path generation, searching features with some spatial and parametric constraint, web interface will pass on request to web server and web server will then pass on the request to a map server through server connector. Subsequently map server will carry out processes in a following sequential manner:
For online temporal data updating web interface will pass-on request to web server, which carries out processes in following sequential manner:
3.2 Data Consideration Data Tier will consist of spatial and associated information about road network topology and point features of interest. Information about each feature class will be stored in the digital format in database management system in distinct tables along with their metadata. Table 1 provides the details of the spatial feature data, along with their type and associated data that are taken into consideration for analysis and subsequent information dissemination. Since spatial representation of road network forms the basis of geospatial analysis that will be carried out by CTIDSS, data structure of the same is discussed in following sections. 3.2.1 Road network topology For vehicle routing, in real world, road network is conceptualized as the well-defined arc-node model (Figure 2 a). Arcs or roads are connected to each other at nodes (intersections). This arc-node model or network topology will form the basis for vehicle routing. Impendence or cost for traversing an edge will be calculated separately for different lanes for each edge and average of them are taken for each direction (Figure 2 b). Further impedance offered by turning movement for one edge to other is maintained in a separate table (Figure 2 c). 3.2.2 Linear referencing system (LRS) topology For reporting the accidents and road blockage sections on roads, Linear Referencing System (LRS) model is used, so that using dynamic segmentation analysis, point events (accidents) and linear events (like road blockage) can be reported with reference to known reference location. For present system, authors have taken starting point of road (in sense of vector digitization of roads) as a starting point and initialized with value of 0. (Figure 3) schematically provide the details of the LRM maintained for linear features.  Figure 1. Proposed conceptual architecture along with public/private function 3.2.3 Bus line topology For transit planning, bus routes are spatial represented as a sequencing of bus lines and bus schedule are maintained for each bus line (Figure 4). 3.3 Basic Functionalities Offered by CTIDSS Major functionalities that CTIDSS will provide are:
 While many of these services will rely on information and infrastructure provided by the public sector, end-user products for these services will be developed and delivered to the end users by the private sector. Sub systems of the deployment scheme are described in the following sections. 4.1 Temporal Data Collection System Temporal information will be collected by highway patrol police, traffic regularity authorities  Figure 2. Road Network Topology  Figure 3. Linear Referencing System (LRS) Topology for Road Network  Figure 4. Bus Line Topology for Transit Planning (like Traffic police) and from transit (public transportation) authorities. Temporal data collected will be relayed to traffic management centre through wireless radios, landline phones, cellular phones or in-person communication. 4.2 Traffic Management Centre (TMC) Traffic Management Centre (TMC) is a centralized management that is responsible for processing, storage and analysis of necessary traveler information. Data Tier and Application Tier will reside at TMC. TMC will be maintained and operated by some public authority like state transportation department, traffic police etc. TMC will process and store temporal data, store spatial data in data tier and carry our geospatial analysis for some request from the travelers. 4.3 Information Service Provider (ISP) Information Service Provider (ISP) is operated and managed by a private-sector company. ISP collects stores and process general information of interest like sports, news, stock market, weather, advertising information etc. and stores it in database. ISP server will disseminate this general information to the travelers on different clients like desktop computers, cellular phones etc. Clients are connected to the server through the Internet. 4.4 Information Distribution System (IDS) Information Distribution System (IDS) will comprise of end-user software for information dissemination to the travelers. The presentation tier of the proposed three-tier conceptual framework will reside at IDS. It will be in the form of an interactive website comprising of user-friendly and interactive maps, links and controls and can be accessed by travelers using web browsers or similar web application programs. Further it will be customizable to suite traveler preference such that contents of website (hot spots, links, and controls) can be added or deleted. The website will also be accessed by authorized traffic regulation personnel for reporting the prevailing the road conditions and other information to TMC and updating the data residing in data tier. 5. Conclusions In this paper, the authors proposed a conceptual architecture of a traveler information system for a metropolitan city in India. This web GIS based system, namely Computerized Traveler Information and Decision Support System, or CTIDSS will not only assist travelers in route planning, proximity analysis and itinerary planning but also make them cognizant with prevailing roadway and traffic condition and schedule of operation of public transportation in real time. The authors presented a web GIS based three-tier conceptual architecture independent of actual implementation for CTIDSS. This approach offers easy scalability and low maintenance costs and exploits rich functionalities of Geographic Information System (GIS). In addition to discussing conceptual architecture, authors also discussed the data used for analysis and information dissemination, basic functionalities that CTIDSS will provide and a deployment scheme associated with implementation of CTIDSS respectively. Private and public sector can collaborate effectively and beneficially so as to provide traveler information to travelers. While the end user application will be developed and maintained by the private sector, information and infrastructure will be provided by 6. References
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