Environmental Engineering Reference
In-Depth Information
Table 2
Comparison of environmental impact of alternative pavement design strategies
Energy
(million MJ)
Pavement type
CO
2
(t)
NO
x
(t)
PM
10
(t)
SO
2
(t)
Traditional
338
19,000
182
151
3,900
Perpetual
230
13,000
123
101
2,600
Difference
108
6,000
59
50
1,300
RHVP Perpetual Pavement
RHVP Deep Strength Pavement
400,000,000
400,000,000
Processes (Equipment)
Materials Transportation
Materials Production
Processes (Equipment)
Materials Transportation
Materials Production
300,000,000
300,000,000
200,000,000
200,000,000
100,000,000
100,000,000
0
0
Initial Construction
Maintenance
Total
Initial Construction
aintenance
Total
Fig. 4
Life-cycle energy consumption comparisons
RHVP Perpetual Pavement
RHVP Deep Strength Pavement
20,000
20,000
Processes (Equipment)
Materials Transportation
Materials Production
Processes (Equipment)
Materials Transportation
Materials Production
15,000
15,000
10,000
10,000
5,000
5,000
0
0
Initial Construction
Maintenance
Total
Initial Construction
Maintenance
Total
Fig. 5
Life-cycle CO
2
emissions comparison
Over the analysis period of 50 years, the energy consumption and the gas and
particulates emissions during the life cycle of the perpetual pavement are reduced
by about one third as compared with the conventional pavement structure. Figures
4
and
5
compare the energy consumption and CO2 emission for both alternatives.
Long lasting or perpetual pavements appear to have clear advantages over con-
ventional asphalt pavements for high volume urban motorways. New mix technolo-
gies such as warm asphalt mixes, the continued and increased use of pavement
recycling are also very promising strategies to achieve more sustainable pavement
designs. To assess the sustainability of alternative strategies it is necessary to con-
sider economic, environmental and social impacts. The economic and environmen-
tal aspects can be relatively easily quantified, but social opportunities are generally
less tangible and so more difficult to integrate in a practicable tool.
