Determining relative weights of sewer pipelines' components and defects

Condition assessment models for sewer network components can be considered a tool for key personnel to make informed decisions regarding the required interventions on the basis of the current conditions of these components. Defect-based models determine the condition of sewer pipelines on the basis of the different defect types and the severity of each defect. In this paper, the different relative weights of defects and components in sewer pipeline segments were determined using the analytical network process (ANP) as an aggregation method. To determine the relative importance of defects and pipeline components, a questionnaire was distributed to experts working in the field of sewage systems and infrastructures. The pipeline segment was divided into three principal components, namely, pipe length, corresponding joints, and manholes, whereas the defects in each component were classified into three defect categories: structural defects, operational defects, and installation/rehabilitation defects. It was found that the pipeline and joint components both had equal relative importance weights of 0.38 each, leaving the manhole component with 0.24. The structural and installation defects' relative weights for pipelines were higher than the operational defects with a value of 0.4 and 0.36, respectively. The structural defects in joints had the highest share, with 0.61 as a relative weight. The relative defects' weights in manholes were found to vary between 0.3 and 0.4.