Assessing Relative Risk for the Failure Modes of a Bridge Scour Countermeasure

Widely used failure modes and effects analysis (FMEA) can be very effective in assessing the relative risks of the failure modes of a bridge scour countermeasure. In this study, an approach is developed for assessing the relative risks of failure modes of a bridge scour countermeasure overcoming the limitations of risk priority numbers (RPNs) associated with individual failure modes. Appropriate application of the RPNs is established by ensuring that high values of RPNs, indicating a relatively higher risk of failure, have higher severity and occurrence ratings compared with the low RPNs, indicating low risk. Replacement of the use of RPNs with risk priority codes (RPCs) enables engineers to prioritize the risks for any severity-occurrence pair using the same scale as the ratings, unlike the RPNs. Given the simplicity and effectiveness of this technique, RPCs are shown to be preferable for assessing and prioritizing the relative risks of the failure modes of a bridge scour countermeasure.