Moving People: Traffic Congestion, Road Building, and Sustainable Transportation Solutions in Urban Areas, страница 8

Yet most State Departments of Transportation are concerned with habitat fragmentation due to traversing highways; this may be due to the fact that roughly 20 million acres, which is approximately the size of South Carolina, have been converted to highways and streets in the United States (NCHRP, 2002).  This amount of road building has brought degradation of habitat quality across the nation; these roads disturb the movement of species by breaking habitats into smaller pieces (NCHRP, 2002).

Furthermore, a study by American Rivers (2002) has linked sprawl to the rapid loss of open space and to deteriorated water quality.  Rain that runs off roadways and adjacent parking lots carries a host of pollutants that contaminate local water bodies.  Under normal circumstances, wetlands absorb precipitation and slowly release it into the ground; undeveloped land provides recreational and aesthetic value, as well as a natural filtration process.  As impervious surfaces (i.e., highways, roadways, parking lots, and driveways) replace open spaces and extend city boundaries, rain cannot seep into the ground to replenish aquifers.  Instead, the polluted rain is swept away by gutters and sewer systems (American Rivers, 2002).  It is a problem shifted to people living elsewhere.

Evidently, both road building and the nonrenewable resources it consumes affect the environment in ways far beyond local or regional congestion.  Climate change stemming from carbon dioxide emissions has global consequences; since the pre-industrial era most of the climate shifts have been attributable to human activities (IPCC, 2001).  Several scientific research agencies attest that the United States should expect more extreme weather events, such as floods and droughts, in the next 100 years due to greenhouse gas emissions (Eilperin, 2005). 

If this is the case, then the United States may need to carefully prepare for such events to avoid any ensuing social-economic disasters; the environmental damages and social-economic impacts from Hurricane Katrina in 2005 will resonate for years to come and should serve as a cautionary

tale.

The developed world, not the developing world, is the primary consumer of energy on the planet.  Studies indicate that increases in a nation’s poverty levels do not correlate with increases in the use of nonrenewable resources.  This is partly due to poor populations’ greater reliance on “public transport (or travel by foot or bicycle), which ensures low averages for oil consumption per person” (Satterthwaite, 2003).  Satterthwaite further explains, “poor urban dwellers generally have much lower levels of consumption for renewable resources than middle- and upper-income groups.”  Yet poorer populations often have been marginalized in urban planning processes; this raises environmental justice concerns.  

The United States Environmental Protection Agency (2006) defines environmental justice as the “fair treatment for people of all races, cultures, and incomes, regarding the development of environmental laws, regulations, and policies.” Applying environmental justice principles to metropolitan planning helps ensure that all citizens benefit from a clean, safe, and healthy environment.  

Poor populations who cannot afford vehicles must be considered carefully in planning for sustainable transportation systems.  Urban areas have become the centers of economic growth. 

These centers then tend to become attractive to immigrants from rural areas and abroad (Florida, 2002).  In many cases, the immigrant populations earn lower than average incomes.  In urbanized areas with infrastructure designed principally for cars, poor citizens may be forced to cope with limited access to jobs, schools, hospitals, and recreational facilities.  The job opportunities accessible to lower-income populations in an urban setting must be reachable within a reasonable commute time; otherwise lower-income groups cannot thrive in that setting.  However, if a city has a broad and patchy geographic layout, then its labor pool will struggle to get to work, particularly if the region’s public transit system is ineffective.  This arrangement is not sustainable in either the short or long term.