Environmental Engineering Reference
In-Depth Information
Fig. 1
Sustainability strives for balance between key indicators
Maximizing Sustainability in Urban Pavement Design
The main topic for this paper deals with applying sustainability principles to road
structural design. Historically, empirical approaches have been used for flexible
pavement design. The accepted life cycle involves periodic routine maintenance
and a major rehabilitation treatment every 18 to 25 years. With the rapidly increas-
ing traffic volumes on urban arterial roadways, larger municipalities are looking for
ways to extend the effective road service life so as to minimize the disruptions to
normal traffic operations and the associated driver delays and inconvenience during
road rehabilitation works. Clearly, huge benefits would accrue in terms of sustain-
ability and value for infrastructure investment if the life of flexible pavements could
be increased to 50 years or more.
It has been observed that energy consumption and greenhouse gas (GHG) emis-
sions during construction and maintenance activities are significant
[2]
. However,
the emissions from vehicles delayed by lane closures during road works are even
larger. Road rehabilitation in urban areas causes serious disruption to traffic and
may require the detouring of traffic through densely populated neighborhoods.
Long life pavements have obvious advantages that can be quantified in terms of
improved environmental quality and reduced GHG emissions. This is especially
important in high density urban environments. Additional benefits are the conserva-
tion of road aggregate and bituminous resources by reducing the need for repeated
removal and replacement of major road elements.
In any analysis of energy consumption and greenhouse gas emissions related to
roads, the entire production and construction cycle must be taken into consider-
ation. A study completed in France
[3]
shows that over a 30 year period, traffic
consumes between 10 and 345 times more energy than road construction over the
same period, depending on the traffic volume. At first this may suggest that the
impact of road design and construction is not a significant contributor to emissions.
On the contrary, when one considers that transportation accounts for 26% of all
