What is Urban Sprawl?
Geographers, urbanists, and other social scientists have attempted to define urban sprawl (or, perhaps more accurately, “suburban sprawl”) for decades. Although nearly as many definitions exist as there are papers on the subject, most would agree that urban sprawl is a spatial phenomenon; it describes a particular kind of urban development that differs in form and function from more “traditional” urban environments.
According to dictionary.com, “to sprawl” means “to be stretched or spread out in an unnatural or ungraceful manner.” When it comes to cities, urban sprawl is essentially just that: it is the stretching of the urban environment, so that it is spread more thinly, or less densely, and consequently covers a larger area.
More specifically, common features of urban/suburban sprawl include:
- Low-density development, consisting mainly of detached single-family houses, strip-malls, “big box” retail stores, and office parks.
- Segregated land use in which residential, commercial, and industrial land uses are seldom or never found in the same development.
- “Leap-frog” development where new development is often not continuous with previous development, leaving large tracts of un- or under-developed lands.
- Auto-dependency due to large distances between destinations and lack of public transit.
- Generic quality, or poor “sense of place” due to lack of community center or unique identity.
A Positive Feedback Loop
All of these features are interrelated and can, in many different ways, encourage one another. Low-density development, for example, is both a product and cause of auto-dependency. The urban sprawl is essentially a positive feedback loop. As people drive more often to more destinations, those destinations become increasingly spread out to accommodate more cars in the form of extra road lanes and parking. This only reinforces the need to own and use a vehicle, as destinations become too spread out to reasonably visit on foot or bicycle.
More cars inevitably means more traffic. On roads and highways, traffic congestion often prompts transportation authorities to consider adding additional lanes. While this may ease congestion for a time, in the end it usually makes matters worse. Reducing congestion, on highways in particular, tends to encourage more people to live further from the city center because commute times are reduced. This “induced demand” eventually results in more traffic, and before long the additional lanes become congested, necessitating even more lanes. Induced demand is thus a well-known phenomena and classic positive feedback loop.
The Effects of Sprawl
Over time, urban infrastructure becomes built around the automobile. It’s amazing how much a city’s land area is devoted to cars. There are roads and highways, of course, but there are also parking lots and garages, gas stations, driveways, repair shops, and car dealerships. All of this land adds space between other useful destinations such as school, work, or the grocery store. It’s also very expensive to maintain. The U.S. Department of Transportation alone spend $100 billion a year, mostly on automotive infrastructure. The total cost worldwide is in the trillions annually.
As homes and businesses become more spread out, other types of infrastructure also become less efficient and more expensive. This includes water, sewer, electricity, as well as city services like fire and police. Imagine a water main, 1 kilometer long, being laid to accommodate new development. Now imagine two scenarios: in the first, only 10 houses are arranged along the road, and in the second, three large apartment buildings with 800 units fill the same space. How much more will it cost the city, per person, in the first scenario? The difference is significant, and cities often lose money providing services to low-density residential areas.
In addition to infrastructure costs, urban sprawl can increase health costs by contributing to poor air quality and the many diseases related to a mostly sedentary, automotive-based suburban lifestyle. In urban environments with low “walkability,” where few people walk for utilitarian purposes, there is a greater chance that daily physical activity needs will not be met. Fewer calories burned translates into more calories stored.
There are many other potential downsides to sprawl, including lower productivity among workers who have fewer chance encounters with others in their industry (i.e., a loss of “knowledge spillovers”), social isolation among those too young or old to drive, or who must drive long distances to reach friends, and generally a decline is social equity and environmental justice as those most affected by the negative effects of sprawl are often disadvantaged groups. For those who cannot afford a vehicle, for example, navigating a sparse and under-funded municipal transit system can be a nightmare. Pedestrians and cyclists are also exposed to roadway air pollution and traffic hazards despite not contributing to these problems themselves.
So what can be done now that (mostly suburban) sprawl has, in many countries, become the dominant pattern of urban development? In what is called “suburban retrofitting”, new, higher-density infill development is helping to make otherwise unwalkable suburban areas much more pedestrian friendly. To instill a sense of place and give a community a proper center, some suburban communities have actually built entire Main Streets or town squares from scratch. Some even resemble in architectural design the Main Streets of old (below).
Importantly, every individual can make a difference by voting with your wallet, your feet, and, naturally, you votes! That is, choose to live a neighborhood with a high enough density and mix of uses to support walking and/or cycling. Live closer to work and your most frequented daily destinations to cut down on the distances you need to travel. Get out and walk. Get to know your city all over again on your own two feet and experience what a city is like — or could be like — for pedestrians. Take public transit if possible and support its funding. Finally, vote for leaders that will encourage infill development, mass transit, and mixed-use zoning. Having strong, anti-sprawl leadership in local government can pay dividends toward ensuring a more prosperous, healthful urban environment.