GIS and Transport Modeling—Strengthening the Spatial Perspective
ISPRS International Journal of Geo-Information
The movement and transport of people and goods is spatial by its very nature. Thus, geospatial fundamentals of transport systems need to be adequately considered in transport models. Until recently, this was not always the case. Instead, transport research and geography evolved widely independently in domain silos. However, driven by recent conceptual, methodological and technical developments, the need for an integrated approach is obvious. This paper attempts to outline the potential of
... potential of Geographical Information Systems (GIS) for transport modeling. We identify three fields of transport modeling where the spatial perspective can significantly contribute to a more efficient modeling process and more reliable model results, namely, geospatial data, disaggregated transport models and the role of geo-visualization. For these three fields, available findings from various domains are compiled, before open aspects are formulated as research directions, with exemplary research questions. The overall aim of this paper is to strengthen the spatial perspective in transport modeling and to call for a further integration of GIS in the domain of transport modeling. Since the beginning of the 21st century, things have changed fundamentally. At least three major innovation paths can be identified. First, ICT (Information and Communication Technologies) has not only changed the way people and goods are moved, but also what we know about this mobility. Within a couple of years the situation has flipped from data scarcity to a deluge of sensors and data streams  ; second, policy is forced to move from the paradigm of an expanding infrastructure to smarter traffic management. Thus, it is necessary to actively manage traffic demand and supply and to activate unused potentials, such as public transit, active mobility, sharing schemes or smart logistics. The required Intelligent Transportation Systems (ITS) rely on accurate data and well-performing communication, management and analysis components, each with a distinct spatial notion [11, 12] ; third, within the transport modeling community, a paradigmatic shift from aggregated models, with the Four-Step Model (FSM) as the most prominent example (see McNally  for an overview), to activity-based and micro-scale models, can be observed. Associated with this shift, the relevance of the geographical space has become widely acknowledged [2, 14] . With regard to the growing integration of geospatial functionalities and transport modeling, this paper focuses on three key aspects which the authors regard as relevant to both: the GIS and transport research community, namely, data for transport models, disaggregated models, and the role of (geo-) visualization. Each of these topics is dealt with from an explicit spatial perspective. The paper is structured as follows: after a brief, general overview of the current contribution of GIS to transport modeling, the three aspects mentioned above are treated in detail. For each topic, the status-quo is described from a spatial perspective. Subsequently, issues as yet unresolved are raised and compiled into key research directions. A concluding section wraps up the major findings. GIS and Transport Modeling: A Brief Overview GIS and transport research have always been interrelated. Thus, it is hard to ultimately decide whether transport modeling is an application domain of GIS or spatial capabilities are incorporated in transport models. Examples exist in both domains and current transport modeling software products increasingly provide integrated GIS capabilities. GIS are capable environments for the capturing, management, analysis and visualization of spatial data. They allow for an integration of various data sources into a scalable, dynamic and adaptable geospatial framework (see Figure 1 ). Through models, simulations and analyses, each with an explicit consideration of the spatial nature of transport, new information can be generated. Besides, GIS also facilitates information visualization which serves as a communication platform with feedback loops to the data integration and the settings of models, simulations and analyses.