Personal computers provide transport planners and engineers with new and powerful means to use computer-based information systems and modelling procedures in their work. The battery of desktop planning tools now available means that modelling can take a more interactive and practical role in the planning, design and analysis of transport systems. Models are now easy to use in the design office, and may even have a role in community participation and information exchange. The use of Geographic Information Systems (GIS) software packages for managing transport databases is of particular importance. This paper describes the need for a systematic approach to transport and traffic modelling and analysis for the proper understanding of travel demand and to provide insights into the traffic and environmental impacts of transport systems management and land use developments. It suggests that a hierarchical system of models and techniques is a valid and useful approach to adopt in these circumstances. A particular hierarchy is given, which is called the "Transport Planning Microscope" (TPM). The use of TPM in the investigation of the impacts of a retailing development is cited, as an illustration of the usefulness of the system in considering a range of likely user impacts. The component models (e.g., DIAMONDS, MONTRANP and MULATM) of TPM are introduced, and the means of linkage and communication between the levels are described.
