How far is too far? Spatial and socio-demographic determinants of 'locked-in' commuting.

摘要

In the United States, people are traveling longer and farther to and from work. They are taking advantage of increasing highway capacity and variety in living and working locations to engage in increasingly inefficient commuting patterns. Commuting required by the spatial distribution of homes and jobs and people's choices within these location choice sets are known to significantly impact observed work travel behavior. The part of observed commuting that is due to people's choices and which potentially could be reduced if people swapped home and job locations is known as "excess commuting" and is the difference between the observed and required levels of work travel. Prior work defines the required level of work travel as the quantitative mismatch of all homes and jobs in a metropolitan area and explains the excess part as the effect of people's socio-demographic characteristics and their housing and neighborhood preferences. These efforts do not adequately address the nature of the socio-spatial underlying required commuting.;It is understood that workers attempt to maximize their location utility within the spatial bounds, offered by urban form, embedded in socio-demographic processes. When making decisions where to live and work, people do not pick from all possible choices; rather, their choice set is smaller and determined by factors such as: occupation; income; race; gender; transport mode; housing age, size and type preferences; access to environmental and leisure activities; school quality and safety concerns. This list shows that socio-demographic and preference factors constrain both home and workplace location choices. It is also clear that people make location decisions within an imperfect labor market suggesting that it is inappropriate to evaluate the efficiency of work trips against a baseline laden with assumptions of perfect competition and information.;The goals of this dissertation are accomplished by: (1) obtaining work trip flows disaggregated by occupation and income; and (2) developing a metric to track people's location strategies relative to local and regional jobs. In order to evaluate the impact of socio-spatial mismatch on observed commuting behavior, an optimization model known as the transportation problem and a spatial interaction model are applied to commuting patterns in Wichita, Kansas and to a sample of U.S. cities. Results from Wichita indicate that the contribution of "locked-in" commuting to observed behavior varies among occupation-income groups. Moreover, empirical evidence from 25 U.S. cities suggests that the required commuting is a more significant contributor than previously thought. This research may benefit planning efforts aiming to reduce commuting through land use change.