Sustainable Urban Mobility: Exploring the Role of the Built Environment by Pericles Christopher Zegras Master of Science in Transportation, Massachusetts Institute of Technology, 2001 Master in City Planning, Massachusetts Institute of Technology, 2001 Bachelor of Arts in Economics, Tufts University, 1990 Submitted to the Department of Urban Studies and Planning in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Urban and Regional Planning at the Massachusetts Institute of Technology September, 2005 © 2005 Massachusetts Institute of Technology. All rights reserved. Signature of Author: _______________________________________________ Department of Urban Studies and Planning 28 July, 2005 Certified by: ______________________________________________ Ralph Gakenheimer Professor of Urban Planning Thesis Supervisor Accepted by: _______________________________________________ Frank Levy Chair, The Ph.D. Committee Sustainable Urban Mobility: Exploring the Role of the Built Environment by Pericles Christopher Zegras Submitted to the Department of Urban Studies and Planning on 4 August, 2005 in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Urban and Regional Planning ABSTRACT 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. 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. Thesis Supervisor: Ralph Gakenheimer Title: Professor of Urban Planning, Massachusetts Institute of Technology 2 ACKNOWLEDGEMENTS This dissertation finds its roots in my first view of the Andean mountains, which I enjoyed on an early Spring morning, arriving in downtown Santiago in September 1991. My experiences living, working, and observing the city’s oddly chaotic order at that time inspired an interest – that turned into a career – in issues involving transportation, urban development, society, and nature. Over the past 15 years, I have had the great fortune of being able to watch Santiago’s rapid evolution, an evolution – evidenced in the transformation of the bus system, the sprouting of “Sanhattan,” the rapid expansion into the foothills, etc. – that leaves me somewhat torn about the city’s current path. In any case, I dedicate this dissertation to all Santiaguinos of present and future generations and hope that my work might provide even a little support in helping them create a “good” (in the Lynchian sense) city. Closer to home, I dedicate this dissertation to Athena, whose love, support and incredible patience during this past year have convinced me she is an angel. Te quiero, te adoro, eternamente. I simply could not have asked for a better dissertation committee. Ralph Gakenheimer has been mentor, teacher, friend and overall fount of wisdom, calm, guidance and humor over the past seven years. I am truly honored to have had the chance to learn from him, work with him, and know him. Joseph Sussman has also been a great source of knowledge, inspiration and motivation for me since I first arrived at MIT and I greatly appreciate his support. Finally, I am sincerely indebted to William Anderson for his agreeing to serve on my Committee; he has been amazingly generous, patient, insightful and encouraging throughout this process. Together, these three people provided the perfect combination of vision, strategy, knowledge, and motivation to get me where I am. I can only say thank you. In Chile, I thank Henry Malbrán Rojas, the Secretario Ejecutivo of SECTRA, for providing access to the origin-destination survey data, the real estate cadastre, and additional data upon which much of the analysis in this dissertation is based. Henry has been a great friend over the years and I would not be writing this right now if it were not for him. Also at SECTRA, I thank Alan Thomas for his kind friendship; both Alan and Esteban Godoy were extremely generous with their time in providing data and other information and answering too many questions from me. At MINVU, I thank Sergio Leon, for providing access to relevant data, and Pedro Muñoz, for providing relevant GIS files and for several very useful conversations. At the Pontificia Universidad Católica de Chile, I thank Juan de Dios Ortúzar for his advice on model development and for answering many questions about the OD survey. Many other people in Chile provided help and friendship over the years. I especially want to thank Edmundo Rojas, Daniel Castillo, Juan Carlos Sáez, los Duharts, y el Flaco. MIT and the Boston area more broadly has been a remarkable place to pursue this research. And the true value of the place comes from its people – people who always 3 seem to know the answer to a question and are willing to go out of their way to help. I have benefited enormously from them. In particular, I would like to thank: Xiongjiu Liao for his help with the GIS data processing underpinning the spatial analysis and, in general, for being an excellent teacher of GIS skills; Jinhua Zhao for several useful theoretical conversations and for reviewing early modeling results with me; Jiawen Yang, who always seemed to be there to help come up with a database query and engage in spirited discussions regarding several relevant concepts; Charisma Choudhury, an excellent tutor in my early use of Biogeme; Mikel Murga, who provided absolutely critical help in developing network level of service measures using TransCAD; Cristian Angelo Guevara, for many useful discussions on model specification; Joseph Ferreira and Rhonda Ryznar, both of whom gave me much of their time in very helpful conversations; Thomas Oles, for an illuminating conversation on modernism and post-modernism planning ideas; Carlo Ratti, for several helpful discussions relating to urban morphology; Joan Walker, for taking the time to talk through some of my modeling issues and patiently sharing her knowledge with me; Judy Layzer for her invaluable comments on my original proposal and helpful advice on the dissertation process; Karen Polenske for great support and strategic advice at several key moments; Larry Vale, for his encouragement and understanding throughout this process; and, many of my fellow Ph.D students (including Liz Reynolds, Apiwat Ratanawaraha, Ryan Tam, La Tonya Green) for commiserating throughout this arduous journey . The linear regression models in this dissertation were estimated with SPSS (version 12.0) and Eviews4 (Quantitative Micro Software). The discrete choice models were estimated with Biogeme (Version 1.0), freeware graciously provided by Michel Bierlaire, of the Ecole Polytechnique Fédérale de Lausanne. Michel also provided many useful modeling suggestions and help. Biogeme’s default optimization algorithm, BIO, was used, as well as, in some cases, DONLP2. For use of the latter algorithm, I acknowledge its author, P. Spelluci and its availability at: http://www.netlib.org/opt/donlp2/. This dissertation would not have been possible without the generous financial support of the Massachusetts Institute of Technology, through a Presidential Fellowship, the U.S. Department of Transportation, through an Eisenhower Graduate Transportation Fellowship, and the Lincoln Institute of Land Policy, through a Dissertation Fellowship. Additional support for data analysis came from the Alliance for Global Sustainability (AGS), through the project, “Designing, Implementing and Measuring Sustainable Urban Development.” Finally, I want to thank my family, to whom I