Studies looking at the relationship between urban form and travel behaviour have generally considered spatial information on coarse metropolitan or local government area scales. We analyse ABS Census data at the Collection District level for the metropolitan areas of the mainland Australian state capital cities, and at various spatial scales for an in-depth analysis of commuting in Sydney. The analyses suggest that the relationship between travel behaviour and urban form is complex, and that simple analyses of density alone are likely to overstate the effect of both metropolitan and neighbourhoodscale population density on mode choice, but that these variables serve as useful proxies for more complex measures of urban structure.
IntroductionThere has been much interest by urban researchers in a variety of disciplines on the relationship between urban form and travel behaviour. The quantity of research in this area is large enough to support large bodies of work investigating (and often advocating) plans and policies to influence urban travel behaviour. For example, research indicating that higher population density, mixed land use, and transit provision result in significant shifts in travel behaviour has been the ammunition for those arguing for urban planning policies that favour higher-density development around public transport nodes (Cervero and Kockelman, 1997;Newman and Kenworthy, 1999). The motivation for such urban compaction is often environmental, although social, health, economic and aesthetic concerns are also cited (Newman and Kenworthy, 1989;Frumkin et al., 2004). Such policies, however, have not had unequivocal support, either in the research community (Troy, 1996;Levinson and Kumar, 1997;Holloway and Bunker, 2005), or amongst the general urban citizenry.The principal aim of this article is not to advocate for or against particular planning policies, as there is an extensive literature on this already 1 . Instead, we will give a brief overview pointing to some of the major relevant publications on both sides, and then proceed with our more descriptive task -conducting an analysis of how spatial structure affects journey-to-work travel behaviour in contemporary Australian cities. We take a spatially disaggregated approach, but without adopting anything as sophisticated as the discrete choice model backed random utility framework typical in modern transport microsimulation, as such an approach would require extensive data collection and model calibration that would preclude us covering all mainland state capitals. Despite the simpler nature of our approach, we believe the breadth and spatial resolution of our coverage provides useful insights into how inter 1 The nature of the data we analyse, however, makes some general policy related remarks inevitable.