Impacts of two-scale urban form and their combined effects on commute modes in U.S. metropolitan areas

This study explores the relationship between urban form at the metropolitan and neighborhood scales and the percentages of four individual modes to commute. It then looks at the combined effects of urban forms at the metropolitan scale in metropolitan areas in the continental United States using multi-level regression models with interactive terms between urban forms. This study contains the percentages for four commute modes: percentage of the vehicle (VT), public transit (PT), biking (BI), and walking (WK). As urban form factors, this study contains urban fragments, population density, job-resident balance (JRB), the percentage of green areas at the metropolitan scale, and distance to the nearest job center at the neighborhood scale. The results show that at the neighborhood scale, a farther distance from individual neighborhoods to the nearest job center is associated with higher VT, and lower PT, BI, and WK. At the metropolitan scale, urban form factors have a more significant association with the percentage of individual modes to commute in large MSAs compared with small MSAs in terms of population. Most urban form factors at the metropolitan scale are not independently associated with the use of commute modes, but their interactions are associated with the percentage of individual modes to commute. Particularly, the level of urban fragments and the percentage of green areas may transform the impact of high population density and JRB on the percentage of the individual modes to commute except for WK. This study provides planners and policymakers with important guidelines to establish combined urban form plans rather than single urban form oriented plans to reduce vehicle travel.