Study On Highway Construction Eco-cost Evaluation

Besides the project cost, the highway construction also incurs ecological cost which includes triple facets of natural resource consumption, environmental pollution and ecological degradation. The simultaneous consideration of project cost and ecological cost could be more comprehensive. However, due to the nonexistence of market exchange of ecological resource, the assessment of ecological cost is formerly disregarded and thereby becomes a difficult issue. Based on the ecological impact analysis of the whole highway construction life cycle, this dissertation proposes a new assessment method, which is expected to fill the gap of the literature.Firstly, based on the life-cycle approach, the highway construction is divided into three stages:preparation, construction, and the end. Then characteristics and severity of highway construction’s impact on the ecological environment at all stages are identified. According to the national norms and standards, the probability of negative ecological impact and the severity of negative ecological impact are portioned into 6 levels. The results show that the severity of resource depletion and ecosystem destruction depends primarily on the design stage, but the environmental pollution mainly derives from the inappropriate construction management; the resource consumption of cement, land use and soil erosion explain the primary negative environmental impact.Secondly, by applying the method of case analysis, literature review and theoretical analysis, based on the type of environmental impact determined by highway construction life cycle environmental impact analysis, this dissertation establishes an index system, which consists of 1 first-level indicator,9 secondary indicators and 34 third-level indicators. In addition, in order to reflect the importance variety of the indicators for the evaluation objectives in construction options, a new method combined by Delphi method and Analytical Hierarchical Process (AHP) is proposed to determine the indicator weights, based on the extent of the various types of environmental impact determined in life-cycle analysis. In order to measure the overall cost of a single building program, an adjustment factor method is proposed to reflect the relative importance of the ecological cost compared with the project cost in different ecological environment deterioration stage.Thirdly, taking account into the environmental impact characteristics of the identified indicators, this disseration compares and analyzes the current environmental impact valuation methods such as market value method, human capital approach, restoration cost method, protection cost method, contingent valuation method, comprehensive evaluation method of land ecological functions etc. Then appropriate assessment methods for indicators are selected. Given that the existing resource depletion assessment methods are not suitable for a single economic activity in this study, emergy analysis method is introduced. Emdollar value can be calculated by transformity emergy/money ratioto assess the cost of resource depletion. Willingness to pay (WTP) conditioned by the income level of respondents is often low, however, willingness to accept (WTA) effected by the respondents’s desire of taking this opportunity to increase revenue is high. Hence, the CVM is refined that the average value of WTP and WTA is treated as the environmental impact value. The joint application of emergy analysis method and the refined CVM provides a more robust method to assess ecological cost.Finally, the proposed method is used in a real world case of Weihai-Urumchi highway. The ecological cost of the two schemes is compared. The application of the case testifies the effectiveness of the method. The result shows that the ecological cost of Weihai-Urumchi is almost equal to the project cost. The main sources of the ecological cost come from resource consumption of cement, land use of woodland and grassland. Therefore, three factors should be considered as more importance when selecting construction schemes. The case results also reveal the characteristics that ecological degradation and resource consumption play an important role in causing highway construction negative impact, whilst environmental pollution playing a small role.