Probabilistic value analysis methodology for public water supply systems

Abstract

The value of a design alternative for constructed facilities is determined based on life cycle cost (LCC) and non-economic performance such as constructability and environmental impacts. Unfortunately, the level of consensus on the results of life cycle cost analysis (LCCA) is low due to the uncertainty associated with cost and timing data for construction, operation, maintenance and disposal of facilities with very long life cycles. Non-economic performance of design alternatives is also evaluated subjectively by the stakeholders of construction projects. Therefore, it is very important to properly manage the uncertainty and the variability of input data for value analysis (VA) of design alternatives. This paper presents a probabilistic VA methodology for public water supply systems. An LCC model and a cost classification structure for public water supply systems were developed to cover the initial and the follow-on cost of public water supply systems that come from the various mechanical systems and the pipeline systems of the collecting/treating/distributing facilities. The proposed VA methodology incorporates the probabilistic results of LCCA and the non-economic performance evaluation based on reliability concept for rational decision making. The model and the procedure presented in this study can greatly contribute to the value-oriented design alternative selection and the allocation of budget for public water supply system construction projects.