By David Dixon FAIA, Leader, Stantec's Urban Places Group
In the wake of 9/11, author Stephen Johnson wrote in Wired that "density kills" and advocated turning to the decentralized vision of Frank Lloyd Wright’s 1939 Broadacre City as a way of protecting Americans in the future. As it turns out, he got it backwards: Density saves lives. The contemporary affinity for higher-density, mixed-use, walkable places in cities and suburbs alike arguably represents the single most significant contribution to public health — for those who can afford them — since World War II.
Healthy density
Five years before the Wired article, the Centers for Disease Control had already reported that inactivity and poor diet caused “300,000 deaths in the United States…second only to tobacco.” That landmark study placed much of the blame on low-density, typically suburban environments whose physical layout encouraged auto trips at the expense of walking, leading to increased rates of obesity, diabetes, and auto fatalities. Today, the health benefits of urban densities are compelling. The incidence of chronic health problems in walkable urban neighborhoods is generally lower than in typical suburban and exurban neighborhoods. A 2008 report by University of Utah researchers found that men who lived in walkable neighborhoods weighed 10 pounds less than men in low-density neighborhoods, a recent Journal of Transport and Health article links cities with more compact street networks to lower levels of obesity, diabetes, high bloop pressure and heart disease.
The data for auto fatalities are particularly stark — per-capita auto fatalities rise roughly 400 percent along a continuum of density from typical urban to typical suburban. Six decades of sprawl have helped give the United States a level of traffic fatalities three to five times higher than other developed countries. Today, auto fatalities represent the #1 cause of accidental deaths in the United States.
Walkability is not an automatic product of density, nor is it restricted to cities. “Walkable densities” outside of downtowns begin at roughly 40-60 units per acre, which translates into one to two thousand households within a five- to ten-minute walk of a neighborhood Main Street. Achieving these densities requires elected leaders willing to make the case for change and developers who understand mixed-use development. Zoning and other regulations, written to enable auto-focused development, often need updating to make denser and more walkable development possible. In many communities introducing walkable density also requires innovative public/private partnerships to work through financial gaps in still-recovering markets or to raise funds to transform brownfields. But even with these ingredients in place, a lingering fear of change — particularly in the form of density — often presents an additional hurdle. In these cases the process starts by engaging the community in planning for a healthier future by providing information and tools to understand the benefits and costs of well-designed density.
The payback from density extends beyond physical health. Walkable neighborhoods promote economic health by attracting knowledge workers and investment and promote environmental health by creating an inviting alternative to sprawl. From Dublin, Ohio, to Sandy Springs, Georgia, to Brampton, Ontario, suburban communities and their leaders increasingly recognize these benefits and have assembled the same ingredients to create a new generation of higher-density, mixed-use, walkable downtowns. However, even as we succeed in redirecting planning toward the creation of denser, healthier neighborhoods, one more task demands our attention.
Equitable density
The benefits of density generate an “amenity paradox” that threatens to translate America’s already egregious wealth gap into a widening health gap between rich and poor. Life-filled, walkable, transit-served neighborhoods have delivered the goods in ways that Jane Jacobs prophesized 50 years ago — with the glaring exception of diversity. Ten percent of U.S. households control 75 percent of all U.S. wealth. They, along with their slightly less affluent peers, are consuming walkable neighborhoods at a voracious rate. This demand is bidding up housing costs and forcing poorer residents into less healthy, car-dependent environments. For the first time in America’s history more poor people live in suburbs than cities. Clustered increasingly at the fringes of car-centric suburbs, yet often unable to afford a reliable car, they are isolated from access to health care — and jobs, education, and support networks.
Nor is this a passing trend. Demographer and economist Chris Nelson projects that over the next 30 years the U.S. will experience a growing shortage of transit-oriented housing. As we employ density to create healthy neighborhoods, we also need to employ it to create equity. The challenge is not market acceptance. Housing economist Laurie Volk points out that many people who choose urban lifestyles seek diversity. In a time of constrained public resources, the answer won’t lie in public dollars. Where possible, we need to tap the rising value of amenity-rich urban neighborhoods to fund the mixed-income housing that makes the concept of diversity real. Density bonuses in return for increased affordability, inclusionary zoning and public benefit agreements represent potential strategies. More are needed.
After decades of disinvestment, cities face an era of opportunity not seen since the Great Depression. To paraphrase that great urban planner, Spiderman, with opportunity comes responsibility. Heading the list of our responsibilities as a society is expanding access — for everyone — to environments that support healthier lifestyles.
About David Dixon
David Dixon FAIA is a senior principal at Stantec and leader of the firm’s new interdisciplinary Urban Places group. He recently published the second edition of Urban Design for an Urban Century: Shaping More Livable, Equitable, and Resilient Cities (Wiley, 2014), co-authored with Lance J. Brown.