The application and development of GPS in transportation

The solution geographic information system is the collection modern computer science, the geography, the information science, the management science and the survey science is a body's emerging discipline. It uses the database, the computer graphics, multimedia and so on newest technology, carries on the data processing to the geography information, can real-time gather, the revision and the renewal geography spatial data and the attribute information accurately, provides the visualization for the policy-maker the support (1). At present in many domains, the GIS technology has been widely applied. Especially in the transportation domain, GIS and the traditional transportation information analysis and the processing technology unified closely, extends the transportation geographic information system (Geographic InformationSystem for Transportation), was called GIS-T.

1 GIS outlined GIS most to get up early stems from the 1960s “to turn the map the digital form the map, was advantageous for the computer processing analysis” goal. in 1963, Canada surveyed scientist R.FTomlinson first to propose GIS this terminology, and used in the natural resource the management and the plan. Among afterward several dozens years, were following the computer technology and the networking rapid development, the GIS application also day by day deepen and widespread, in domains and so on environment, resources, petroleum, electric power, land, transportation, public security, aviation, municipal administration management, urban planning became the standing-by work system. GIS is technical and so on graphic processing technology, visible technology and database organic synthesis, and establishes a new school by its blended data structure and the formidable geography spatial analysis function. It (database management system) and so on has the very big difference with the CAD system and DBMS. Although the CAD system has the formidable graphic processing ability, but its analysis situs relations are quite simple, the management and analysis large-scale geography database's ability is also limited; DBMS stresses in the non-graphic data optimization saves and inquires, but the graph inquiry, the demonstration function, the data analysis function relatively is weak. It is well known, in GIS the most foundation is also the most important part is the geography data. GIS can realize to the massive complex geography data input, the memory, the operation and the analysis, the output and so on a series of functions. Input: The GIS data majority from the real world, the data quantity is quite big. At present the data feeds method which widely uses is the traditional manual digitized method. At the same time, the remote sensing data is becoming the GIS data day by day the important origin, this symbolizes that the GIS data feeds already started with the aid in the non-map form. Moreover, the GPS technology mature also promoted the GIS data acquisition technology development day by day. Memory: GIS is quite unique to the data memory, namely has used the lamination technology generally in the majority GIS systems, therefore user when saves these data, is only processing involves the level, but is not the view picture map, can thus make the rapid reaction to user's request. Operation and analysis: GIS has inherited CAD and the DBMS graph operation and the data processing mature technology fully. In GIS the spatial data and the attribute data have the close relation, is high to the data uniform request, and GIS has the formidable spatial analysis function to the geography data. This is the GIS essence is, is also the GIS technology can in many domains the widespread application key. Output: GIS can by the appropriate form output user inquiry result or the data analysis result. Regarding the output accuracy requirement high application domain, may using the data correction, the edition, the graph retouch, technologies and so on error cancelling, coordinate transformation to improve the output quality. Because in GIS data processing is quite tedious, the work load is big, already was completely unable through the manual way to meet the current need, must therefore use computer's handling ability fully, with the aid of assists in the software system to complete these work. At present the GIS domain quite mature software has American ESRI Corporation's Arc/Info, Mapznfo Corporation's MapInfo, Intergraph Corporation's MGE and so on.

In recent years, along with geographic information system's swift development, more and more application domains has established the close relation with the GIS technology. Because the transportation information system has the accuracy requirement to be high, the rule is complex, discretization characteristics and so on tendency, the original information technology already could not satisfy the transportation application completely the demand, but with the aid in the GIS formidable function, may realize the transportation informationization time request. In the transportation domain the GIS application also more and more receives the researcher and exploiter's value. The transportation geographic information system is the collection, the reorganization, the memory, the management, the generalized analysis and the processing spatial information and the transportation information computer software and hardware system (2), is the GIS technology in transportation domain extending, is GIS and many kinds of transportation information analysis and the processing technology integration. GIS-T has the formidable transportation information service and the management function, it may apply in traffic control each link. Uses the GIS technology and the method study transportation plan, the transport facilities and the traffic control and the related question in the traffic engineering domain, has the other conventional routes incomparable merit. In the 1960s, the US Bureau of Vital Statistics has established DIME as well as afterward TIGER data model, at that time they have used express the road system based on and the line univariate linear network. In these with the line between two points connected attribute list, has recorded line between two points each kind of attribute information. , This kind of pattern has been since the road traffic system expresses the model a mainstream. But along with social and the economical development, the road traffic system becomes day by day complex, is getting higher and higher to the transportation geographic information system's request, GIS-T will face more challenges. 3 GIS-T key technologies GIS-T improved GIS and TIS (transportation information system) marriage. At present are many researchers to devote to the GIS-T research and the development, revolved GIS-T to have the many research subjects, the different research subject involved the GIS-T function also had the difference. In order to carry on the detailed explanation, may through define 3 function groups to obtain an general frame, these 3 function group is: The data management (realizes data storage and maintenance), the data manipulation (realizes the model which primary data's innovation), the data analysis or the establishment may analyze. They are the interdependence support mutually, the data storage is the data manipulation premise, but the data modelling is also establishes in the first two foundations. 3.1 database management system since long, the Traffic department must use and maintain the massive information, in many situations is many transportation information system coexistence in the identical department, moreover each transportation information system can only process some class number according to what is believed rest (for example highway plan network, highway administration system as well as accident information and so on). The GIS-T data management system's key technologies lies in through the establishment data model and the data exchange frame, the above different data storage in a unified data management system, any department can visit in this system to conform to the data which this department requests, simultaneously can carry on the analysis and the modelling to these data, then carries on the management and the decision-making.