An integrated ANP and er condition assessment model for sewer pipelines

As sewer networks age, the need for their maintenance arises. Simultaneously, inadequate rehabilitation of sewer pipelines might cause catastrophic failures. Thus, municipalities worldwide must have a detailed knowledge on their networks condition. New condition assessment models for gravity and pressurized sewer pipelines were developed using ANP, FST, and ER. Seventeen factors were considered for gravity network in addition to the operating pressure for pressurized network. The considered factors were grouped under physical, environmental and operational categories. Based on the obtained results, the three main categories were found to be almost equally important for gravity pipelines. On the other hand, the environmental category was found to have the highest impact with more than 50% effect on pressurized pipelines, while the operational category was found to have the lowest impact with a 5% effect. The sub-factors recorded importance weights varying within the range of 8% for gravity pipelines and 15% for pressurized pipelines. The "Ground Disturbance" factor was found to be the most influential factor followed by the "Location" factor. On the other hand, the least affecting factors were "Length" and "Diameter". The obtained results were validated with 15%, 85%, 0.12, 0.15, and 893 for AIP, AVP, MAE, RMSE and fi, respectively. The proposed condition assessment model can provide key personal and decision makers with a proper tool to plan their inspections, collect only necessary data and provide cost effective rehabilitation and maintenance action.