GIS in Transport Modelling

This dissertation consists of five papers and an introduction. In Barriers in travel models, the focus is on modelling mobility in border regions, both borders within nations and between nations. We use travel surveys and networks from Sweden and Norway to model the barrier effect caused by the borders in the region between two counties on each side of the national border. In Identifying local spatial association in flow data we develop a statistic for spatial association for flow data by generalising the statistic by Getis and Ord (1992) and Ord and Getis (1995), Gi and Gi . This local measure of spatial association, Gij , is associated with each origin-destination pair and can thus be used for explorative analysis of e.g. matrices of travel flow. In Detecting barrier effects we use a modified Gij-statistic, G(Γ), in an attempt to identify barrier effects in flow data. The G(Γ) approach for studying barrier effects is compared with the traditional approach of using dummy variables to model the barrier as in Barriers in travel models. We conclude that the G(Γ) is more flexible than the usual dummy variable approach in an explorative spatial data analysis. One central evaluation criterion of the transport system is accessibility. In Path based accessibility we develop an aggregate accessibility measure that takes one mandatory activity pattern into account i.e. travel to work trips. This measure can be used to evaluate accessibility obtained from multi-purpose trips. In Experiences from GIS based travel demand modelling we summarise our experiences from different types of GIS–model integration. We present a model system that consists of tools for zone design, model estimation, scenario calculation and accessibility analysis. When using GIS as a modelling environment, we have not encountered any limitations with regard to model implementation and design of the user interface. Furthermore we found the GIS environment excellent for data preparation, accessibility analysis and visualisation of model output.