Land Use and Transport Mode choices: Space Syntax Analysis of American Cities

Natural movement theory (from space syntax literature) postulates that configuration of the urban grid is an important generator of aggregate patterns of movement in urban areas (Hillier et al. 1993). In addition, movement economy theory asserts that retail and commercial activities migrate to configurationally hotspot locations to take advantage of the economic opportunities created by movement (Hillier 1996). These concentrations of retail and commercial activities are also the work places for a good number of people and in turn, will influence the choices of residential locations. Since journey-distance and time are two very important factors influencing transport mode choice, (Plaut 2005; Wardman, Tight, and Page 2007; Pucher and Dijkstra 2003; Schwanen and Mokhtarian 2005). This paper hypothesized that the locations of retails and commercial areas as understood by their space syntax derived configurational index, will first affect the choices of residential locations and also influence choices of commuting mode.

This hypothesis is tested in four US cities of Boston, Pittsburgh, Lubbock, and Salt Lake City using data collected from online open source database of the respective cities and US census bureau. Space Syntax topological and angular analyses of CAD drawn axial lines and street centerlines extracted from GIS maps are performed for all cities. ArcGIS spatial analysis tools were applied to combine land use, socio-economic & demographic, transportation and Space Syntax variables to the scale of census block-groups that was selected as the study unit. Multiple regression analyses are carried out to identify relevant and significant variables explaining each mode of transport. The findings indicate that Space Syntax variables play an important role in explaining choice of commuting mode. In addition, several linear regression analyses are performed to examine the land use and transport mode choice in the context of street configuration. The results indicate that commercial and retail concentration were positively correlated with integration cores. Following general trend of space syntax findings, commuters tend to live at configurationally segregated areas while walkers and bicycle riders tend to live in configurationally integrated areas where commercial and retail activities are concentrated. Regarding the differences of layout types, the results of comparative analysis between gridded and non-gridded cities indicates that closeness variable called ‘integration' and between-ness variable called ‘choice' are relevant to explain walking and driving modes in non-gridded and gridded cities respectively.