Geo-spatial analysis of activity spaces in a TOD environment – Tracking impacts of rail transport policy using kernel density estimation

Activity spaces are dynamic, 'people-based' accessibility measures that can be used to analyse spatial arrangements of travel. This paper reports on activity spaces in the context of transport policy aimed at changing travel behaviour by offering alternative transport options and new urban services within transit-oriented developments (TOD) environments. Specifically, we explore associations between TOD and activity spaces to derive visually easily comprehensible indicators, assisting practitioners and policy makers in determining decision-making effectiveness. We analyse results from household travel diaries collected within three unique TOD precincts in Perth, Western Australia situated alongside a 72 km new metro-rail link, pre- and post-opening, to identify impacts of the major transport intervention on travel. While activity spaces have increasingly been applied as metrics for assessing the extent of urban space used by households for satisfying their daily activity needs, their application to explore potential changes in built environment induced travel behaviour is a novel feature of this research. We employ herein kernel density estimation, which has great flexibility and superior visualisation capabilities in representing activity spaces, to longitudinally track travel behaviour changes. We also expand on previous investigation that considered discrete origin-destination trip data, by applying kernel density estimation to data including generated route information. Our findings suggest benefits of activity space analysis in investigating past transport infrastructure decisions and associated implications, promising a potential improvement for development of new policies and strategies in the transport sector.