The spatial and temporal dynamics of commuting : examining the impacts of urban growth patterns, 1980-2000

Abstract

The dissertation is broadly concerned with the issues of urban transportation and urban spatial structure change. The focus of the research is to interpret the increase in commuting time and distance in the last two decades. The major hypothesis is that a significant proportion of commuting length increase can be explained by land development patterns, particularly the spatial relationship between workplace and residence. The biggest challenge to address the above problem is to design a method that characterizes job-housing proximity and correlates commuting with job-housing proximity consistently across space, over time and among different regions. A thorough evaluation of existing measures, including ratios of jobs to employed residents, gravity type accessibility and minimum required commuting, shows that all have serious problems. The dissertation presents a new approach - the commuting spectrum - for measuring and interpreting the commuting impacts of metropolitan changes in terms of job-housing distribution. This method is then used to explain commuting in two sizable but contrasting regions, Boston and Atlanta. Journey-to-work data from Census Transportation Planning Packages (CTPP) over three decades (1980, 1990 and 1990) are utilized.

(cont.) Results indicate that the configuration of commuting spectrums mirror the changes in urban spatial structure in terms of job-housing proximity. In addition, the spatial variation, temporal change and regional differences in commuting can be significantly explained with job-housing proximity. Empirical results suggest that spatial decentralization pathways in Atlanta and Boston change the regional patterns of job-housing proximity, attracting people to commute longer distances. The relatively constrained spatial decentralization in Boston results in shorter commuting time and distance than in Atlanta. The empirical results point to a constrained and balanced vision of urban growth for achieving a commuting economy. Both urban growth management and transportation policies are needed to help achieve this vision.