Sustainable urban mobility : exploring the role of the built environment

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2005.Includes bibliographical references (p. 231-265).This dissertation examines the concept of sustainable mobility within an urban context. In essence, the research aims to answer the question, "What role does a city's built environment play, if any, in the sustainability of its mobility system?" To answer this question, I first derive an operational definition of sustainable mobility: maintaining the capability to provide non-declining accessibility in time. Providing non-declining accessibility depends on our ability to maintain net capital (natural, human-made, social) stocks, or, at least, the capability of these stocks to provide current levels of accessibility to future generations. In other words, we can think of a more sustainable mobility system as one that provides more welfare per unit of throughput, with welfare measured by accessibility and throughput measured by mobility. This is a normative framework. It can only indicate relative levels of sustainable mobility. Within a specific city, this framework can allow us to measure which parts of the city produce more sustainable mobility patterns. To employ this framework, I utilize a utility-derived accessibility measure.(cont.) The attractiveness of a utility-based accessibility metric comes from its basis in welfare economics, its ability to account for individual characteristics and preferences, and the possibility for its derivation from the random utility-based models (e.g., logit), which have a long tradition of use in transportation planning. Also, drawing from the large research base exploring the role of the built environment on transportation, I develop several models that assess the influence of the built environment on travel behavior, in particular, motor vehicle ownership and use. These models, combined, enable the exploration of sustainable mobility within a given city. I apply the framework to the city of Santiago de Chile, utilizing data from a 2001 household travel survey and a 2001 real estate cadastre, specifying a nested destination and mode choice model, and examining a subset of discretionary trips by seven different travel modes. Variations by income, gender, and modal availability are explored. I conclude with a discussion of the implications in the face of current urban growth patterns in Santiago.by Pericles Christopher Zegras.Ph.D