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Global Positioning System: A useful tool for Intelligent Vehicle-Highway Systems(IVHS)
Dynamic Route Guidance (DRG)
Dynamic route guidance systems are being designed to provide route recommendation based on actual or predicted traffic conditions based on data gathered from an equipped network. Watling and Van Nuren provide a comprehensive discussion of DRG systems to 1 st generation systems, such as VMS. Advanced Traveler Information Systems (ATIS) ATIS are an integral component of Intelligent Transportation Systems (ITS). The provision of real time information to traveler will lead to more efficient distribution of travelers to routes and modes. Many ATIS integrate highly defined mapping with GPS to enable real time vehicle tracking. These systems are capable of positioning the vehicle, determining if the vehicle is on or off course, and making appropriate adjustments to routing strategies to help the traveler navigate through the network to the intended destination.  Fig.1: Schematic layout of the Experiment Real-Time IVHS and GPS GPS has the ability to collect and store large amounts of useful data. If these data could be used in real time then we can have large number of application in IVHS. If data such as percentage stopped time and speed of a probe vehicle circulating in a network could be known in real time, then assessment can be made as to where congestion levels are highest. This is feasible, given a good communication system. This information could be relayed to the public as part of a traffic user information system (e.g. Koutsopoulos and Xu, 1993; Collier, 1993) , for instance providing drivers with warnings to avoid areas where congestion-related delays are expected. Methods for IVHS application include the use of advance warning signs and electronic billboards along the highways to display this information, and radio stations devoted to providing the public with details of current traffic situations. Public transport could also greatly benefit from GPS. Commuters could be informed of the likely arrival time of the next buses and also notified of any delays or deviation from schedules that may have been encountered. Planned Experiment on Real-Time GPS-GIS Integrated Systems It is planned to develop a Real-Time GPS-GIS integrated system on experimental basis, which can be used for vehicular guidance, vehicle tracking, fleet management and many other applications, like travel time and delay studies. As a first step in developing such a system, a compatible interface is being developed between GPS and GIS. The GIS platform that is being used is TransCAD, which is the first and probably only GIS software, designed specifically for use by the transportation professionals to store, display, manage, and analyze transportation data. This integrated system will display the position of the vehicle on GIS map, after getting data from GPS receiver, and will direct the vehicle to its destination. When the traffic conditions ahead are known beforehand, this system will be able to display alternative routes to reach the destination. Software will be developed to find the shortest path between given origin and destination among all possible alternatives routes. In the experiment that is planned to be carried out on some of the important roads of Mumbai road network, GPS will be fitted to a probe vehicle and used to collect position, time and speed data of the vehicle. GPS receivers that are being used for this purpose are Trimble Pro-XR / Trimble Geo-Explorer single frequency receivers, and TRIMBLE 4000SSI dual-frequency receivers. The data thus collected will be processed in real-time domain and accurate position of the vehicle will be shown on the GIS map on the notebook PC kept inside the vehicle. This can in dynamic guidance of the vehicle. Post-processing with the same data can be done for travel time and delay studies of different routes. The schematic layout of the proposed experiment is shown in Fig. 1. Acknowledgements This work is being carried out as a part of B. Tech. Project by the first author, under the guidance of second author, at the Department of Civil Engineering, Indian Institute of Technology Bombay (IITB). The instruments being used for this purpose include Geoexplorer, Pro-XR, and 4000SSI models of Trimble Navigation Ltd., which are made available by IITB, and Department of Science & Technology, Govt. of India. References
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