Failure forecast and hydraulic reliability models for rehabilitation decision aid

One objective of the CARE W project is the testing and validation of tools providing indicators useful for rehabilitation decision aid. Two types of tools were studied: statistical failure forecast models (FFM) and hydraulic reliability models (HRM). The former, based on previous failure records, compute failure rate (or number) by individual piper or by pipe category, while the latter compute pipe hydraulic importance in terms of pressure deficiencies or available consumption. For FFM, tests consisted of comparing results of forecasted with observed failures, according to validation indices on two European networks. First tests show a good correlation, depending on the lengh of recorded data and the covariates used. For HRM, results of the models were compared and the possibility of failure risk consideration was studied. These two types of model can be applied either in an Annual Rehabilitation Programme, as indices useful in defining rehabilitation criteria and for pipe prioritisation, or in Long Term Rehabilitation Strategies, to provide pipe survival curves or to forecast iindices according to rehabilitation rates.