Introduction
The urbanism-related research articles in this section of the website were curated by Senior Research Associate, Dr. Michael w. Mehaffy in collaboration with Dean Stefanos Polyzoides, Professor Marianne Cusato, Dr. David Brain, and former Mayor of Carmel, Indiana, James Brainard.
The curated research draws on a wide range of international journals and disciplines. to report on the impacts of urban form as they affected social, economic and environmental outcomes. In particular, we looked for literature addressing research questions on specific issues of concern to practitioners and policymakers at this moment in urban history. We wanted to know, for example, does the evidence show that more walkable neighborhood designs result in better health? That more compact forms of development are likely to result in reduced taxpayer costs for municipal services? If these and other findings are conclusive, then how can such features be implemented successfully?
Summary of Findings
After formulating a series of additional research questions, we conducted multiple literature searches to find well-cited, conclusive research papers in reputable journals (and a few well-cited and influential books) across a range of disciplines. We then selected representative papers and compiled them into a curated database of (as of this writing) 222 citations with abstracts, as well as a companion repository of the actual documents. The process of curation was meant to identify representative papers that addressed the research question, and that could provide meaningful guidance for policy and practice. Of course, as with any investigator, our assumptions, questions and biases affected our selection – but we have endeavored to be transparent in making them known and open to challenge.
Following, then, is a summary of the key conclusions we have drawn from the research herein. It should be emphasized again that these are our own conclusions drawn from the evidence, and not necessarily those of the original study authors – although we do find that our conclusions are solidly grounded in the evidence presented by those authors, which we discuss in detail. These conclusions are, in many cases, drawn from multiple studies – that is, composite conclusions that “connect the dots” and point toward actionable pathways for practice and policy. As is the case with any research-based guidance, this knowledge should be applied in conjunction with observation, refinement, and adjustment to local conditions and outcomes. It should also be applied with an awareness of the inherent limitations and biases of any investigator, including ourselves.
For the sake of clarity we have begun by grouping the findings into comparisons between two broad classes of urban form. They are:
- Traditional City Form (TCF): a relatively compact, walkable, mixeduse urban pattern, typical of many cities and towns around the world prior to 1930.
- Modern City Form (MCF): a more functionally segregated, less walkable, lower density form that relies primarily on the automobile for most kinds of urban travel, typical of most newer parts of cities and towns built after 1945.
Following is a summary of the impacts identified in the research literature:
Economic Impacts
- A TCF can reduce municipal infrastructure construction and operation costs of streets and utilities per capita, translating into substantial savings for municipalities and taxpayers.
- A TCF can substantially reduce municipal costs for fire, police and ambulance, also translating into substantial savings for municipalities and taxpayers.
- A TCF that includes walkable street improvements can see notably improved economic activity and value, with significant uplifts in retail rental values, a substantial decrease in retail vacancy rates, and greater economic resilience in retail types compared to unimproved areas.
- A TCF can increase economic development opportunities and attract new businesses, by providing a denser mix of creative businesses helping to generate a lively and attractive environment for new businesses and their employees.
- A TCF can generate increased property values, helping to fund municipal improvements and increase local wealth, in combination with strategies to maintain affordability for lower-income populations.
- A TCF can promote affordability and reduce household expenses of car ownership and operation by reducing the number of trips and the number of vehicle miles traveled, by increasing proximity and lowercost access to daily needs and services, and by reducing the need to own and operate one or more vehicles.
- A TCF can reduce costs for businesses by reducing the cost of land, construction and maintenance for parking spaces.
Safety Impacts
- A TCF can substantially improve pedestrian and passenger safety while preserving functional mobility, by reducing vehicle speeds with narrower lane widths and slower traffic.
- A TCF can promote safety from crime by providing natural surveillance and co-presence of strangers, reducing the opportunities for crime and the measurable incidence of criminal acts by strangers.
- A TCF can improve resilience and ability to respond to crises, by promoting more compact growth in safer areas, and by fostering connectivity and building social infrastructure.
Health Impacts
- A Traditional City Form (TCF) can improve physical health in comparison to a Modern City Form (MCF), primarily by promoting walking, biking and exercise. In more built-up areas, reduced automobile use in favor of walking, biking and transit use can also improve air quality and respiratory health.
- A TCF can improve mental health through physical exercise (which also confers mental health benefits), social contact (which reduces loneliness and social isolation), and aesthetic stimulation, particularly in neighborhoods with a rich mix of aesthetic experiences including varied and detailed traditional architecture.
- A TCF can improve social trust and cooperation by providing the “social infrastructure” that creates awareness of neighbors and their needs, which often translates into supportive relationships with neighbors. In either case, this connection to neighbors is important especially in times of crisis, promoting cooperation and resilience. It is also important more generally in fostering cohesion and “social capital,” or cooperative networks between the residents of an area.
- A TCF can foster social interaction and participation in local groups by facilitating incidental encounters, relationships, and knowledge of (and invitations to) local activities.
Environmental Impacts
- A TCF can preserve ecosystems and farmland by reducing urban land cover through more compact development patterns.
- A TCF can reduce emissions that contribute to climate change and that degrade air and water quality in urban areas, by facilitating lowemissions travel and lifestyle options, and by reducing impervious cover per capita.
- A TCF can facilitate resilient and climate-friendly planning, including reduced heat island effects, improved thermal comfort and mitigation of heat stress events, reduced stormwater runoff, and improved social capital and cooperation in extreme events.
- A TCF that includes conservation and adaptive reuse of existing buildings can achieve a substantial diminution in environmental impacts, notably a significant reduction in global warming gases, smog formation, acidification, and water runoff impacts.
Implementation Resources and Strategies
- TCF can be successfully achieved in part with new regulations, including mixed-use zoning, form-based coding, “middle housing” ordinances, and related resources.
- TCF can be successfully achieved with new economic tools, including tax increment finance, land value tax, “feebate” incentives, targeted grant programs, true-cost accounting for fee structures and assessments, and similar innovations.
- TCF can improve the beauty, livability and desirability of an area by promoting walkability, coherent public spaces, supportive traditional architecture, and integrated park and open space designs featuring water and other natural elements.
- TCF can achieve better environmental performance with urban greening, careful design of water infiltration systems, and reduction of residents’ “ecological footprint”.
- TCF can improve livability and safety, including during extreme events, by providing features that increase thermal comfort, including urban greenery, reduced pavement, and air flow strategies, and by concentrating new development in safer areas.
- TCF can include affordable housing that is financially feasible, and does not compromise the safety or quality of life of other residents. It can thereby reduce homelessness, in concert with other measures.
- TCF can succeed without tall buildings, which are unnecessary to achieve sufficient compactness, and they create a number of negative impacts on affordability, social interaction, adjacent public spaces, and sustainability.
- TCF can support child-friendly and senior-friendly cities, by providing safe, attractive and engaging streets, pathways and public spaces.
- TCF can increase opportunities for healthy food and local economic activity by providing spaces and facilities for local markets.
- TCF can improve the quality of urban development with carefully deployed collaborative planning processes, like charrettes, tactical urbanism, pattern languages, transect-based planning, and related innovations.
- TCF can be more popular and successful when its public spaces are framed and defined with supportive types of traditional architecture, which as research shows, is favored by most users, and has measurably better performance in promoting user well-being and other outcomes.
Social Impacts