Application of geographical information systems to regional road-networks planning in Hong Kong

Abstract

Traditionally, in dealing with Urban Transportation Planning System (UTPS) models, both complex attributes and spatial data should be collected extensively to proceed a sequential four-step analysis: (1) trip generation, (2) trip distribution, (3) modal split and (4) network assignment. However, this approach faces two obstacles. First, the data required is usually spatially referenced and difficult to manage in a traditional database system. Second, the UTPS modelling road-network has often been developed in a simplified form with limited topographical relationships among road links and junctions. This is inadequate in presenting a realistic road-network for modelling analysis in UTPS. With the introduction of Geographical Information System (GIS), the above mentioned problems can be solved. GIS is a computerized database management system for the capture, storage, retrieval, analysis, and display of spatially referenced data. With the aid of GIS, attribute and spatial information related to traditional UTPS models can be manipulated in a comprehensive manner. Besides, realistic graphical representations of road-networks can be achieved by the cartographic functions provided in the GIS. More importantly, GIS has provided a new basis for complex spatial analysis in the traditional UTPS process. The aims of this research are to identify the underlying principles and requirements for developing a prototype GIS database for transport planning at a regional level, and to illustrate the potential applications of the database in the context of UTPS process. The research proceeds in four phases: (1) development of prototype GIS-Transportation (GIS-T) database in a district of South-East Kowloon Re-Development Area by using Intergraph MGE, (2) incorporation of multimedia information in the GIS-T database, (3) accessing the existing network-flow characteristics within the study area by using the prototype GIS-T database and (4) evaluation of future road-network assignments by using TransCAD. In particular, the analytical aspects and applicability of GIS in UTPS are demonstrated in the context of network-flow characteristics and assignment analysis. The results show that the prototype GIS-T database would refine the database management process and the major road-networks within the study area can be simulated realistically under GIS's environment. More importantly, the use of GIS allows transport planners to modify and query the graphical linked database. The system's quick spatial query make possible responses to questions that arise during transport planning, and attention can be focused on an affected local link or area. Therefore, in the process of speed-flow analysis, the GIS can identify all the spatial orientation and related attribute information of the congested links at microscopic level. In addition, scenario analysis can be performed in a comprehensive manner with the aids of mapping functions provided by the GIS. Comparison between existing and future network-flow change in a pre-defined study area is conducted in terms of traffic volume, V/C ratio, and travelling speed. The results are interactively displayed in graphical formats and therefore, transport planners can gain a better understanding and insight to assess the performance of the proposed transportation system. The thesis is concluded by discussing the current research issues and directions in this field.