Asset Management Perspective in Long Term Rehabilitation of Aged Water Distribution Networks

Traditionally, the rehabilitation and/or upgrade of water distribution networks (WDNs) are performed with only one perspective with the aim to bring a long-term reliable system to supplying the consumers. On the contrary, such systems are not isolated but interdependent with other adjacent networks including urban drainage and road networks. This means that the performance and rehabilitation schemes of different networks could have direct or indirect impacts on each other, requiring coordinated infrastructure management strategies to be adopted. For example, the pipe replacement in a WDN could interrupt a traffic flow on a co-located street, or a flood could prevent water utility staff from accessing the section of a WDN pipe, thus making maintenance infeasible. Furthermore, if different infrastructural activities (operation, maintenance, rehabilitation and upgrading) are not planned in an integrated way, there will be a high risk of redundant activities in the same location, imposing unnecessary costs. This implies that in the decision-making process for the rehabilitation of a WDN, the status and plans of other correlated urban systems should be considered simultaneously. In this study, the single and multi-utility rehabilitation of a simplified real world WDN are planned, as a part of asset management process, by the aid of a multi objective optimization engine in which the objectives are utility practices cost and outcome reliability measures. Then the results are compared and discussed in terms of pros and cons of the two mentioned approaches.