The FMEA (Failure Modes and Effects Analysis) was used for management of failure risks of the sewerage system of Algiers. It’s based on a multi criteria analysis of failures risks of principal structures, their effects and their criticality. The implementation of criteria is based on the knowledge gained in previous phases of investigations. A criticality index "Ic" has been estimated to highlight the most sensitive structures to previously identified risks. This index is calculated based on three parameters: a "risk", a "severity", and a "detectability period" of the failure. Multi criteria analysis was performed to select and rank the criteria on the basis of scores assigned to each of them (from 0 to 7 according to the defined performance states). Four performance classes were defined according to the values of Ic. Classification scale and graphs representing criticality indices were established. A case study is presented. The results highlight the "black points" of the sewerage system. The most sensitive structures have been identified and the targeted interventions in the medium and long terms have been proposed. The weak points of FMEA were also highlighted.
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