Optimal Inspection Decisions for the Block Mats of the Eastern-Scheldt Barrier

To prevent the southwest of The Netherlands from flooding, the Eastern-Scheldt storm-surge barrier was constructed, has to be inspected and, when necessary, repaired. Therefore, one is interested in obtaining optimal rates of inspection for which the expected maintenance cost is minimal and the barrier is safe. For optimisation purposes, a maintenance model was developed for part of the sea-bed protection of the Eastern-Scheldt barrier, namely the block mats. This model enables optimal inspection decisions to be determined on the basis of the uncertainties in the process of occurrence of scour holes and, given that a scour hole has occurred, of the process of current-induced scour erosion. The stochastic processes of scour-hole initiation and scour-hole development was regarded as a Poisson process and a gamma process, respectively. Some other examples of the application of gamma processes for modelling deterioration will be discussed as well. ABOUT THE SPEAKER Prof. Dr. Jan M. van Noortwijk is a senior adviser in Risk and Safety at HKV Consultants, Lelystad, The Netherlands, and a part-time professor in 'Mathematical Aspects of Risk Analysis' at the Faculty of Electrical Engineering, Mathematics and Computer Science of Delft University of Technology. His consultancy areas and research interests include maintenance optimisation, life-cycle costing, risk analysis, classical and Bayesian statistics, uncertainty analysis, expert opinion, and process planning. He has published over 40 papers in scientific journals, books and conference proceedings, and is currently supervising 2 PhD students. Since 2000, he is also head of the Risk & Safety group of HKV Consultants in Lelystad. His website is ssor.twi.tudelft.nl/~jan/. Information: Robin Nicolai; rnicolai@rsm.nl