Geography Reference
In-Depth Information
static population. The metropolitan area of Pittsburgh (Pennsylvania) lost 12% of its
population between 1970 and 2000, but it continued to spread over the hills on both
sides of the Ohio Valley, while density decreased in the city's center and in the
industrial valleys. Conversely, the Atlanta metropolitan area is a model of economic
success and population growth. Between 1970 and 2000, the population of today's
metropolitan area increased 230%. Atlanta can be considered as a prototype of the
American city which expanded with urban sprawl. Chapter 8 therefore takes Atlanta
as the starting point for the study of factors and problems that are associated with
recent urban sprawl in the United States. Since Atlanta is a special case, in terms of
its very strong growth, its example will be systematically compared to that of
Detroit. Indeed, the capital of the US automobile industry is often labeled as the
prototype of the American city in crisis.
7.3. Consequences of urban sprawl on sustainable development
The problem with urban sprawl is urban connectivity. As demonstrated by Paul
Claval [CLA 81], the real purpose of transactional metropolises is to optimize
communication networks. Regardless of the density of neighborhoods, a
metropolitan economy can only function effectively if its neighborhoods are
connected by an efficient network of transportation and communication. US cities
differ from those of the rest of the world by their very low population density and
widespread distribution of jobs. This leads to an exceptional degree of car
dependency [NEW 89]. The urban sprawl that occurred throughout the 20th century
in the United States led to the inexorable decline of public transportation to the sole
benefit of the automobile. Urban connectivity now relies mainly on the network of
urban highways. The economic efficiency of this model relied for a long time on its
flexibility, and its ability to ensure access to affordable housing with relatively low
commuting time [MER 95] for such big cities. Less than 4.7% of Americans used
public transportation to get to work in 2005, and 77% of drivers commuted alone in
their car. US cities are gridded by highway networks, free for the most part, but
congestion is such that the average commuter loses 54 hours per year in traffic
(2004). In the early 1980s, Americans traveled 2,400 billion km/vehicle per year.
The time lost in traffic congestions accounted, at the time, for 12% of the average
duration of the home-work commute during rush hour. Car traffic increased by 94%
between 1982 and 2004. Time lost in traffic congestion has since increased by
167%, extending by 37% the average commuting time at peak hours. What was once
an economic advantage is deteriorating with the increasing congestion of the traffic
network, while consideration for the environment, affected by pollution, increases.
The resulting overconsumption of fuel adds greatly to the country's emission of
greenhouse gases as well as to the increase in smog and ozone peaks in metropolitan
