Keywords: life cycle cost analysis, highway, pavements, construction, maintenance, sustainable construction, decision making, resource allocation.

The decisions for highway development have been traditionally based on economic criteria and most importantly on the initial construction costs with little or no attention paid to the various aspects of costs and performance during the life cycle of a road. The present work aims to develop a framework for life cycle cost analysis of highway projects incorporating the sustainability dimensions of project development. The proposed system consists of modules for performance prediction of major road elements in time, for cost estimating and life cycle cost analysis and for optimising investment decisions. The deterioration of road elements strongly affects several cost components, such as maintenance and user costs. Deterioration prediction models for pavements have been derived based on expert knowledge employing fuzzy systems. For bridges and structures, statistical information from practice about defect evolution has been employed.

The costs associated with a highway project can be grouped in general into four categories, namely agency costs, user costs, other costs, and negative costs. The agency costs consist of the design, construction, maintenance and operational costs. User costs involve vehicle operating costs, travel time costs and accident costs. Other costs mainly refer to environmental impacts, in particular vehicle emissions, noise pollution, natural resource depletion, and ecological impacts. Negative costs relate to the value of the asset at the end of the analysis period. The cost components described previously have been classified according to the main sustainability dimensions (economic, social, and environmental).

The system development aims to provide two types of decision support. The first uses the calculated life cycle cost of a highway design, appropriately weighted according to sustainability requirements and objectives, to evaluate the project performance under different sustainability scenarios. The second decision support direction is towards selecting appropriate highway projects to be implemented within a region considering the transportation needs, resource availability as well as any desirable constraints in impact levels. An integer programming model is used in which the objective function includes two independent and generally contradictory goals, to select cost-effective projects and to allow the implementation of as many projects as possible. This is done by a goal programming procedure in which individual goals are prioritised be setting appropriate weights. The above type of analysis can assist optimal allocation decisions of scarcely available resources and also rationalise decisions on a higher level regarding the amount of resources that should ideally be allocated for highway project implementation.

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