A Qualitative Model of the Reliability-Maintenance Cost Relation of Critical Hydraulic Structures in Support of Complex Modeling and Communication of Model Results

The flood protection of the Netherlands critically hinges on the full readiness of their storm surge barriers. A strict form of risk-based asset management is applied to ensure a good condition. This method relies on detailed reliability models that explicitly link maintenance to performance. In this way, safety standards should be met in an efficient way and without unnecessary maintenance investments. Nevertheless, the necessity of investments often appears hard to explain. This may be caused by the fact that the reliability models rely on strong but implicit assumptions about how the maintenance is performed. Therefore, one could question the credibility and usability of the aforementioned models.
Here, we introduce a simple, S-shaped model that transparently explains the impacts of a wide range of maintenance strategies on the storm surge barrier performance. This model can be used for the communication with decision makers and to qualitatively assess on what aspects the underlying reliability model could be refined to optimally support the asset management. The added value of the model is illustrated on the basis of the asset management practice of the storm surge barriers in the Netherlands.

Keywords: Storm surge barrier, Reliability modeling, Asset management, Maintenance, S-curve, Bathtub curve, Flood risk.