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Global Positioning System: A useful tool for Intelligent Vehicle-Highway Systems (IVHS)
R.Naveen Kumar Goud
4/4 Civil engineering
E-mail: naveengoud_r@rediffmail.com
P.Vishnu Vardhan
4/4 C.S.E
E-mail: vardhan_82@yahoo.com
Vasavi College of Engineering
Abstract
Methods for automatic vehicle monitoring (AVM) form an integral component of Intelligent Vehicle-Highway Systems (IVHS) technology, with many IVHS applications requiring information on the real-time location of vehicles. The Global Positioning System (GPS) offers an efficient and economic method to the users, who need only provide suitable receivers to obtain precise coordinates and other related information, using the GPS satellite system. This paper deals with the use of GPS as a method for obtaining information on the position, speed and direction of travel of the vehicles, in the IVHS. The various issues involved in this task include the use of GPS receivers tailored for mobile applications, and their ability to provide direct observations of vehicle speed and travel direction. This, coupled with database management using Geographic Information Systems (GIS) software, can provide a reliable and efficient system for vehicle monitoring, navigation and tracking. GPS has the ability to collect and store large amounts of data. 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, for instance providing drivers with warnings to avoid areas where congestion-related delays are expected.
Introduction
Research and development work in IVHS relies on the availability of methods of locating and monitoring vehicles (e.g. “probe vehicles”) in real time, across a road network. Zito et al, (1995), have studied the usage of GPS for Intelligent Vehicle Highway Systems (IVHS). Some of their observations and conclusions drawn from the experimental program are:
- GPS can provide useful real-time data on vehicle position and speed, provided that account is taken of the quality of the signals received in judging the usefulness of the observed data.
- The choice of GPS receiver capability is important in vehicle monitoring applications.
- GPS direct speed measurement should always be used in preference to speeds calculated on the basis of vehicle positions over time.
- The number of satellites the receiver is able to track (NSAT) and the PDOP give an indication about the reliability of the speed data.
- GPS, when integrated with GIS, is a valuable tool for travel time studies.
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