Environmental Engineering Reference
In-Depth Information
9. As a result of an increase in transit use, traffic congestion in residen-
tial, work and commercial centres may decrease [62].
10. Public transit can be more energy efficient. Handy highlights that it
is the set of choices correlated with density—not density itself—that
shapes travel behaviour [63]. In this context, Bannister discusses the
interaction between socioeconomic circumstances and people's pro-
pensity to travel with different frequencies, trip lengths and trans-
portation modes [59]. Moreover, gender should be added to these
intervening variables [64]. Self debates the effect that a change in
density would make. He claims, for example, that a 50% increase in
the density of Canberra, Australia, would produce only a modest
increase in public transit use [65].
11. It offers more opportunities to walk or ride a bicycle to work, service
and entertainment facilities [59,60].
12. High densities may result in economies of scale that facilitate the use
of better quality and more attractive building materials [51].
13. It enables the use of a building complex as an element of the urban
composition. It also allows for a variety of densities and types of
construction in a given region. Variation in density and construc-
tion, in turn, makes the environment more interesting [51].
14. High-density development in the proximity of public transportation
lines can decrease the demand for land located further from these
lines [66].
15. High-density development as infill in existing areas can revitalise
those areas and can reduce the pressure to develop open spaces [61].
On the other hand, urban density is a major factor that determines the
urban ventilation conditions, as well as the urban temperature. Under given
circumstances, an urban area with a high density of buildings can experience
poor ventilation and strong heat island effect. In warm-humid regions, these
features would lead to a high level of thermal stress of the inhabitants and to
increased use of energy in air-conditioned buildings. However, it is also pos-
sible that a high-density urban area, obtained by a mixture of high and low
buildings, could have better ventilation conditions than an area with lower
density but with buildings of the same height. Closely spaced or high-rise
buildings are also affected by the use of natural lighting, natural ventilation
and solar energy. If not properly planned, energy for electric lighting and
mechanical cooling/ventilation may be increased and application of solar
energy systems will be greatly limited [67].
2.3.2 Land-Use Distribution and Home-Work Trip
The distribution of uses over the city plan is the main driving or restraining
force of transportation. It is those trips made to different facilities that shape
