Enhancement of Pavement Condition and Its Impact on Pavement Sustainability: Environmental and Economic Assessments

摘要

The cost saving regarding vehicles operation, travel time and road maintenance has one eye-catching benefit via increasing pavement sustainability through maintaining the material sources and reducing the emissions of gases resulted from the processing of derivative products. Furthermore, the rate of increase of traffic on unpaved road is considered as a strong indicator to construct paved roads over this area. In the present paper, the Nasiriya-Abu Ghar road was studied. It is one of the important unpaved roads. Its importance lies in the transport of construction materials from Abu Ghar quarries to the near provinces in Iraq, such as Dhi Qar Province. Abu Ghar quarries are considered as one of the most important quarries because it contains different construction materials such as gravel, limestone and sand. These materials have high engineering properties. Thus, the absence of a paved road linking Abu Ghar quarries with the surrounding areas, especially the province of Dhi Qar, encouraged to conduct a technical and economic feasibility study to highlight it and to help the decision-makers to implement the project. The present study contributes in statement of the economic and environmental feasibility of the construction of a new suggested road over the old unpaved one. The study depends on the hypothesis that the old road has a bad condition while the new one is an asphaltic concrete pavement with a good condition. The manual counting method of traffic volume was used from 7:00 am to 4:00 pm for 7 days to determine the peak hour volume and average daily traffic. Road's construction and maintenance costs were estimated. Saving in the road user costs for both existing (old) and new-suggested roads were calculated to be considered as benefits. The economic study is achieved by comparing the discounted total road costs and their benefits to the basic year (starting year of the project). In the present study, the adopted discount rate is 8%. To find the economic feasibility, some criteria were tested. These criteria are: Net Present Value (NPV), Benefit–Cost Ratio (B/C) and Internal Rate of Return (IRR). The results show that NPV has a positive value equals to 40,269,371 US$, which means that benefits are greater than costs. Furthermore, B/C ratio was 2.54; comparing with a value of 1.0, which is encouraging. Finally, the IRR was located between discount rates of 20% and 25 %, with a value of 22.9% which is higher than 8% "the recommended in the road projects".