An increasing number of cities in Canada and the United States hope to retrofit car- dependent suburban areas into walkable, transit-oriented communities to achieve goals related to health, sustainability, and economic productivity. However, they often struggle to do so, because in car-dependent environments, wide roads and parking lots discourage walking, and because there tends to be substantial political and institutional barriers to redistributing space from cars to pedestrians. In this thesis, I ask why cities struggle to implement suburban retrofits, and what forces could facilitate change? I explain the challenge by analyzing car-dependence and walkability as two self-reinforcing, path-dependent design paradigms that exist in fundamental tension with each other. I label this tension "urban intercurrence," and draw on the literatures of American Political Development, historical institutionalism, policy feedback, and urban planning to theorize why it is difficult to transition from one paradigm to another. I categorize these tensions into three types of self- reinforcing process: institutional, political, and transport-economic (the interaction of development and transportation).
I explore these ideas in four case studies of retrofits in Canada and the United States: Surrey City Centre, BC; and the Uptown Core, Oakville, ON; Downtown Kendall, FL; and Tysons, VA. For each, I review historical documents and interview a range of actors, including developers, engineers, urban planners, politicians, and community advocates. I find evidence in support of the idea that car-dependence is self- reinforcing, and that political, institutional, and physical barriers exist for walkable design in car-dependent contexts. I also find, however, evidence of considerable progress, and I offer two additional hypotheses to explain processes of change. I propose that to initiate a retrofit, proponents can utilize contradictions that exist within car-dependence, including backlash amongst car-dependent voters against the consequences of car-dependence. To complete the process of change, however, walkable interests, institutions, and development would need to reinforce walkability on its own terms, and rely less on car-oriented institutions and voters to justify change. I bolster these claims by reviewing the history of how walkable design was first supplanted by car-dependence in the early twentieth century.