Impacts of the Built Environment on Active Travel: Evidence from 20 US Metropolitan Areas

Abstract

Background/Aim: Walking and bicycling are health-promoting (e.g., physical activity) and environmentally friendly (e.g., reducing emissions) alternatives to the automobile. Previous studies have used city-specific traffic counts to assess correlates of active travel and the built environment; however, lack of spatial and temporal coverage of traffic counts on a national scale precludes generalizability from these studies. Our work aims to address this limitation by modelling the relationship between the built environment and active travel at a national scale. Methods: We sourced and aggregated pedestrian and bicycle traffic counts over 15 years for 20 US metropolitan areas (n=6,342 count locations). For each count location, we tabulated various land use, traffic, accessibility, and socio-demographic variables at 12 buffer sizes (100-3,000m). We used stepwise linear regression to develop four base-case models for morning and afternoon peak-hour bicycle and pedestrian traffic volumes. Results: Our models demonstrate reasonable goodness-of-fit for both bicyclists (adj-R2: 0.36-0.47) and pedestrians (adj-R2: 0.70-0.73). Built environment features were significant across all four models. In general, areas with easy access to water bodies, high rates of active commuting, as well as industrial, retail, and service land uses were associated with higher bicycle and pedestrian volumes (household density was associated with pedestrian volumes only); precipitation was associated with lower volumes. Cross-validation of our models (via a Monte Carlo 10% hold-out) showed a modest (~0.01) drop in adj-R2 across models. Conclusions: Our work offers insight for designing health-promoting cities. For example, our models could be used to estimate exposure to hazards such as crashes and air pollution. By incorporating bicycle and pedestrian counts across many cities, our models provide more generalized estimates of the magnitude of the impact of land use on zero-emissions travel behaviour to improve air quality and increase physical activity.