Research And Development Of Webgis-based Urban Transportation Geographic Information System

Following with the rapid development of computer and network technologies, WebGIS has gradually getting deeply into the urban traffic management. This research is to develop the Urban Transportation Geographic Information System (UTGIS), which is an application and extension of WebGIS technologies in the transportation field. This is implementation of road network analysis and traffic announcement through the Internet. With UTGIS, the processes of road network analysis become more intuitive, easy and efficient. The goal is to enhance the operating efficiency in today's road network analysis. It is an inevitable trend in urban traffic development and management to apply WebGIS based system. Such systems allow urban traffic management, road network analysis, and decision supports.UTGIS focuses on the topology of road network and its storage, management, and expression issues. UTGIS applies the research methods in graphics theory with the consideration of the road network connectivity model. With a warrant on the integrity of the traffic characteristic geometry, the design of UTGIS applies a GIS-T model, which is a non-polar data model and is suitable for expressing the urban road network. In maintaining the consistency of the topological relationship and the topological automation, UTGIS applies different designs in the network topology and the geometric data. This approach can reduce the redundant road attribute data. Furthermore, from the foundation and research of data model, UTGIS allows the extraction, development, modification and simplification of geometric topological features in urban road network.The design of UTGIS aims at the key issues in WebGIS, and it applies the technologies in J2EE, JSF, ArcGIS WebADF frameworks. The design also combines the spatial database management engine, and the Ajax and XML technologies for urban traffic Geographic Information System. In announcing the traffic information, UTGIS applies the disntribution computing model in WebGIS, and it utilizes the database, the application server (ArcGIS Server), the web server and the client side four-tier architectures. With the special characteristics in the web applications and the network conditions such as the Internet communication speed issues, UTGIS adopts a mixed-mode to achieve the GIS features at the client side and the distribution features of spatial processing at the server side. It achieves a loading balance between the client and the server. At the client side, the Ajax technologies can enhance the user experience, while, at the server side, the ArcGIS WebDF technologies can achieve the features and logic in spatial analysis. Finally, UTGIS is applied to a simplified base road network data in Hangzhou, i.e. Hangzhou Urban Geographic Information System. The optimization goal of the system aims at the road network accessibility, the traveling time and the distance, and it also consider the sequence of stations and the restrictions on turning directions. This Hangzhou UTGIS implements the urban transportation route guidance and the function module of the Dijkstra algorithm.