Simulation-Based Condition Assessment Model for Sewer Pipelines

Condition assessment models are considered as an evaluation tool that can be used by decision makers to accurately evaluate and assess the condition of pipes. Condition assessment of pipes helps in reaching better decisions in terms of repair or replacement before their failures. This paper presents a condition assessment model developed for gravity and pressurized pipelines in sewer networks using integrated fuzzy analytical network process (FANP) and Monte Carlo simulation techniques. Factors affecting gravity and pressurized pipelines in sewage networks were studied and included in the developed model. A questionnaire was distributed to experts in the field, to determine the weights of 17 factors for gravity pipelines, in addition to the operating pressure for pressurized pipelines. The developed model uses a weighted scoring system to determine a numerical value indicating the condition of pipelines. FANP was used to determine the weights of the factors affecting pipeline assessment, while Monte Carlo simulation was used to determine the final scores by probability distributions fitting. Actual data for an existing sewage network in the state of Qatar was used to validate the developed model. The developed model was able to satisfactorily assess the conditions of deteriorating sewer pipelines with an average validity of approximately 85%. The developed model is expected to be a useful tool for decision makers to properly plan for their inspections and provide effective rehabilitation of sewer networks.