Urban sprawl is the extension of low-density residential, commercial, and indust
Urban sprawl is the extension of low-density residential, commercial, and industrial development into areas beyond a city’s boundaries that occur unplanned or uncoordinatedly (Figure 1). It is generally characterized by the following:
- low-density development that is dispersed and situated on large lots (greater than one acre)
- geographic separation of essential places such as work, home, school, and shopping
- high dependence on automobiles for travel
- increased impervious surface area in watersheds
- habitat fragmentation and degradation
Urban sprawl combines low density and fragmentation of the urban area (Figure 2), increases the average travel distances for daily trips, and hinders a shift toward less energy-intensive transportation modes. The sprawling nature of cities is critically important because of the major impacts of increased energy, land, and soil consumption. These impacts threaten the natural and rural environments, raising greenhouse gas emissions that cause climate change and elevated air and noise pollution levels, often exceeding the agreed human safety limits. Thus, urban sprawl produces many adverse impacts that directly affect the quality of life.
Health
If communities are not walkable or bikeable, we must drive to schools, shops, parks, entertainment, play dates, etc. Thus we become more sedentary. Residents of sprawling counties were likely to walk less during leisure time and weigh more than residents of compact counties. A sedentary lifestyle increases the risk of overall mortality, cardiovascular disease, and some types of cancer. Low physical fitness’s effect is comparable to hypertension, high cholesterol, and diabetes.
Consumption of Energy
The growing energy consumption is a consequence of the increasing consumption of land and reductions in population densities as cities sprawl. Generally, compact urban developments with higher population densities are more energy efficient. Evidence from 17 cities worldwide shows a consistent link between population density and energy consumption (Figure 3), particularly high energy consumption rates associated with lower population densities, characteristic of sprawling environments, dependent on lengthy distribution systems that undermine efficient energy use.
Transport-related energy consumption in cities depends on various factors, including the nature of the rail and road networks, the extent of the development of mass transportation systems, and the modal split between public and private transport. Evidence shows a significant increase in travel-related energy consumption in cities as densities fall. Essentially, the sprawling city is dominated by relatively energy-inefficient car use, as the car is frequently the only practical alternative to more energy-efficient, but typically inadequate, relatively and increasingly expensive public transportation systems. Increased transport-related energy consumption is, in turn leading to an increase in the emission of CO into the