Criticality model to prioritize pipeline rehabilitation decisions

Abstract

Sewer networks are comprised of a huge maze of underground pipelines. They are designed and laid to transfer sewage medium to treatment plants or disposal areas. However, their conditions are subject to deterioration owing to ageing. The American Society of Civil Engineers claimed that the sewer infrastructure grade is D+. Inspection, assessment, and effective decisions are required to enhance their performance through their service life. There are several inspection methods and assessment models that can evaluate the condition of the pipelines. When evaluating the global network, the city or municipality will end up having thousands of pipeline conditions. Therefore, they confront obstacles in deciding which pipelines to tackle first. The objective of this study is to design a criticality model that is based on multiple factors that could affect the criticality of one pipeline to another. The study evaluates the weights for the environmental, economic, and public factors as well as their subfactors by using the analytic network process (ANP). The results concluded that the most important factor is the economic factor. The criticality model is implemented on an actual case study brought from the city of Edmonton, Canada. Based on the results, 20% of the pipelines are of low criticality; 70% are of medium criticality; and 10% are of high criticality. This study is expected to enhance the prioritization of the pipelines in the network for efficient future decisions.