Condition assessment of sewer pipelines using multi attribute utility theory (MAUT)

Abstract

Many municipalities rely on the interpretation of Closed Circuit Television (CCTV) inspection reports to arrive to a condition assessment grade for the inspected sewer pipelines. The grades stand as a key for decision makers in their maintenance and rehabilitation plans. The paper will propose a condition assessment for sewer pipelines using Multi Attribute Utility Theory (MAUT). The condition assessment model utilizes MAUT to generate utility functions for four sewer pipeline defects: deformation, settled deposits, infiltration and surface damage. Minimum and maximum values were adopted, where applicable, from the Water Research center (WRc) to build the utility functions. The grades are changed to 0 to 10 utility scale to plot the points considered. The deformation defect utility curve was polynomial of degree two and the coefficient of correlation (R2) was exactly 1. However, the settled deposits defect utility curve was polynomial of degree three with R2 of 0.9993. The proposed model aims to provide information for asset managers about the severity of some sewer defects existing in sewer pipelines. In addition, it reinforces their plans for rehabilitation and maintenance by suggesting the existing condition of the sewer pipelines.