Explaining intraurban variations of commuting by job proximity and workers' characteristics

Based on the Census for Transportation Planning Package (CTPP) 1990, in this paper I will attempt to explain intraurban variations of commuting time and distance in Columbus, OH. Whereas commuting times are directly available from the CTPP, commuting distances are recovered by GIS network techniques as the shortest-time distances through the urban road network. Explanations of commuting are first attempted by measures of job proximity such as distances from employment centers and a gravity-based index accounting for job competition among workers. The influence of employment centers on commuting sheds new light on polycentric urban models. The variation of commuting distance is well explained by the gravity-based job proximity index. That is to say, how far people commute is explainable to a large extent by urban land use. However, how much time people spend on commuting is complicated by their socioeconomic status, which affects their choice of commuting modes. Finally the research demonstrates the promise of explaining commuting times by workers' characteristics such as percentage of black workers, female labor participation ratio, percentage of multiple-worker households, home-ownership status, educational attainment, and wage rate. In the analyses, spatially lagged dependent variables are introduced to control for the effect of spatial autocorrelation.