کاربرد GIS/GPS در حمل و نقل

کاربرد GIS/GPS در حمل و نقل - GIS/GPS in transportation GIS/GPS in transportation Changes in technology, particularly information technology, are having an increasing impact on transportation systems and how we travel. Many automobile manufacturers now install car navigation systems. Personal communications service (PCS, or cell phones) and personal digital assistants (PDAs) affect urban locational and travel behavior. Location-based systems (LBS) will soon be able to use a combination of such technologies to advise travelers of the best route from point A to point B. Using PCS and PDAs, location-based systems will guide travelers to geographic locations, restaurants, gas stations, museums, and other objectives. Information technology also affects us in that any one or more of these telecommunication means may be substituted for face-to-face contact, making travel unnecessary in some cases. The basic tools that make these new technologies possible are geographic information systems (GIS) and global positioning systems (GPS). Both systems are currently being deployed in the transportation industry, providing a number of benefits such as enhanced mobility, congestion reduction, improved air quality, reduced transportation system operating costs, improved access in general and for specific disadvantaged groups, improved safety, and enhanced competitiveness and economic development. Figure 1 shows how GIS and GPS work in the transportation industry. Fig. 1 Concept for the workings of GIS/GPS in the transportation industry. Gateway services enable one network (such as a wireless network) to communicate with other networks such as the Internet or an intranet. GIS refers to Global System for Mobile Communications. Intelligent transportation systems One of the paradigms and goals within the transportation industry has historically been to transport the maximum number of people and goods at a minimum cost and distance. However, travelers in many modern metropolitan areas frequently take outer beltways, which often are longer distances but faster routes across the city. So, the real issue is not distance but time. Because of advances in computing and information technology, major opportunities now exist for the redesign of entire transportation systems such as the development of advanced vehicle control systems, including systems for guidance and for the scheduling of vehicle operations. To put this in perspective, it is estimated that over $86 billion would be required to construct 44,300 additional lane-miles of road to meet projected traffic demand in the 50 largest United States cities over the next 10 years. Yet the same capacity could be achieved for about $56 billion by fully deploying intelligent transportation systems (ITS) throughout the same cities, supplemented by building only 14,700 new lane-miles. Intelligent transportation systems integrate wired and wireless information processing and communications, serving, display, and control technologies to surface transportation. Integrating these technologies with the transportation systems and vehicles will save lives, time, and money by monitoring and managing traffic flow, providing alternate routes, and reducing congestion, to give a few examples. A projected $209 billion will be invested in ITS between now and the year 2011 in the Unites States alone, with a full 80% of that investment coming from the private sector in the form of consumer products and services. Intelligent transportation systems equipped with GIS and GPS (combining digital maps with navigational information) offer a novel way of increasing the capacity and performance of the traditional physical infrastructure through accurate and dynamic vehicle tracking in order to alert users of traffic conditions and provide them with alternate route guidance. GIS During the 1990s, geographic information systems were applied extensively in many areas of planning, programming, project development, and implementation. The generic GIS may be viewed as a number of specialized spatial routines, laid over a standard relational database management system. With GIS, it becomes easy to capture, store, retrieve, query, process, analyze, visualize, and report upon spatial data. GIS identifies a spatial entity by its location, pattern, or shape, based on analysis of continuous, multidimensional space. Its four significant capabilities are (1) spatial data processing and manipulation; (2) linking spatial and descriptive data; (3) representation of spatial relationships among spatial entities containing topological relations—connectivity and contiguity, metric relations such as direction and distance, and ordered relations (for example, above, below, in front, and behind); and (4) spatial operations such as spatial analyses. The use of GIS in the transportation industry offers many advantages. It can describe spatial features accurately, and enable the user to ask and answer “where and what” questions. Once spatial data are stored in a GIS database, it becomes easy, inexpensive, and quick to update, maintain, retrieve, map, and generate reports. The display functions of GIS are helpful for checking spatial errors, manipulating data, and interpreting results (Fig. 2). The dynamic segmentation function in GIS provides efficient means of handling and processing linear geographic data. Locational data on a link such as accident location, pavement condition, and traffic volume can now be analyzed and displayed along with link attribute data. GIS can provide spatial information such as data on topology and metric relations, which is necessary for spatial analysis. With this information, spatial statistical analyses, such as spatial autocorrelation and surface trend analysis, can be performed efficiently. By providing easy access to alternative analyses and simulation, the spatial analysis capabilities of GIS can generate new information that is needed for decision-making and policy analysis. For example, potential GIS solutions include finding the best location for a branch office when implementing a proposed urban development plan, and suggesting alternate routes if a disaster such as a tornado occurred. Fig. 2 GIS for integrating transportation data. Both locational and attribute (descriptive) data are shown in the box for a segment of the Alaska Highway indicated by the arrow. GPS Positioning technology is fundamental for transport operations to become a location-aware service. The Global Positioning System is a constellation of U.S. government satellites providing the most advanced and accurate positioning and navigation services. The NAVSTAR (satellite) system, operated by the U.S. Department of Defense, was the first global positioning system widely available to civilian users. Currently, 24 GPS satellites (21 navigational and 3 active spares in 12-h orbits 12,000 mi above the Earth) constantly transmit their precise time and position in space. Six orbital places are equally spaced to provide a user with between five and eight satellites visible from any point on Earth. Four satellites are required to compute the four dimensions of position and time. GPS receivers in vehicles listen to these satellite signals and use the information to determine the location of the vehicles, as well as how fast and in what direction they are moving. GPS is also being used in many new market applications because its capabilities are accessible using small, inexpensive devices. Telematics—wireless fleet tracking and vehicle management systems—provides drivers with personalized information, messaging, entertainment, and location-specific travel and security services. On the consumer side, handset-based location solutions predominate in the United States. The Federal Communications Commission (FCC) Act for enhanced 911 emergency services, called wireless 911, mandates the wireless industries to equip the automatic location identification (ALI) providing accurate location of the users. It mandates that the wireless industries provide all new handsets to be ALI-capable by the end of 2002, and that carriers provide ALI-capable services to all subscribers by the end of 2005. At the same time, the FCC clarified that carriers may block fraudulent 911 calls from nonservice initialized phones pursuant to applicable state and local law enforcement procedures. A few available commercial products receive free location-determining signals from the U.S. government's GPS and free accuracy-enhancing signals from the U.S. government's Wide Area Augmentation System (WAAS), having the ability to process positioning fixes at a rapid-fire rate of five times per second. Some other products deliver automatic routing, detailed mapping, and WAAS capability. They usually come with a GIS-based compact disk that gives the user access to detailed street-level maps with locations of restaurants, hotels, and other services. When the user looks up a location, the products automatically calculate a route and guide a user to a destination, with turn-by-turn directions and audible beeps that alert the user to upcoming turns. See also: Database management system; Geographic information systems; Highway engineering; Satellite navigation systems; Transportation engineering Bibliography R. R. Stough and G. Yang, Intelligent transportation systems, in T. J. Kim (ed.), Transportation Engineering and Planning, in Encyclopedia of Life Support Systems (EOLSS), EOLSS Publishers/UNESCO, Paris, 2003 Ali Fazeli = egeology.blogfa.com J. C. Thill (ed.), Geographic Information Systems in Transportation Research, Elsevier Science, Oxford, 2000 Ali Fazeli = egeology.blogfa.com J. You and T. J. Kim, Development and evaluation of a hybrid travel time forecasting model, Transport. Res. C, 8-1,6:231–256, 2000 Ali Fazeli = egeology.blogfa.com Additional Readings Global System for Mobile Communications Ali Fazeli = egeology.blogfa.com Location Based Services Report Ali Fazeli = egeology.blogfa.com Expanding Agenda of Geographic Information Standards Ali Fazeli = egeology.blogfa.com Pendleton, Greg, 2003, “GPS/GIS Integration” Ali Fazeli = egeology.blogfa.com Global Positioning System Ali Fazeli = egeology.blogfa.com Time Difference of Arrival (TDOA) Method of GPS Technology Ali Fazeli = egeology.blogfa.com Location Content Drives Wireless Telecommunications

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