Assessing Built Environment Walkability using Activity-Space Summary Measures

摘要

There is increasing emphasis on active transportation, such as walking, in transportation planning as a sustainable form of mobility and in public health as a means of achieving recommended physical activity and better health outcomes. A research focus is the influence of the built environment on walking, with the ultimate goal of identifying environmental modifications that invite more walking. However, assessments of the built environment for walkability are typically at a spatially disaggregate level (such as street blocks) or at a spatially aggregate level (such as census block groups). A key issue is determining the spatial units for walkability measures so that they reflect potential walking behavior. This paper develops methods for assessing walkability within individual activity spaces: the geographic region accessible to an individual during a given walking trip. We first estimate street network-based activity spaces using the shortest path between known trip starting/ending points and a travel time budget that reflects potential alternative paths. Based on objective walkability measures of the street blocks, we use three summary measures for walkability within activity spaces: i) the average walkability score across block segments(representing the general level of walkability in the activity space); ii) thestandard deviation (representing the walkabilityvariation), and; iii) the network autocorrelation (representingthe spatial coherence of the walkability pattern). We assess the method usingdata from an empirical study of built environment walkability and walkingbehavior in Salt Lake City, Utah, USA. We visualize and map these activity spacesummary measures to compare walkability among individuals’ trips withintheir neighborhoods. We also compare summary measures for activity spaces versuscensus block groups, with the result that they agree less than half of thetime.