Infinite maintenance horizon
Arno: “Years ago, we advised the Directorate-General for Public Works and Water Management (Rijkswaterstaat) on the risk-based maintenance of dikes, dams, dunes and floating marks, so-called ‘hydraulic line objects’. Initially, we developed a method that enabled us to estimate the risks for the coming 6-year maintenance period. Based on that, we optimised the maintenance for that relatively short period. However, this approach is not optimal for the lifespan of the assets and can still lead to wrong choices or even failing assets. Moreover, the DirectorateGeneral for Public Works and Water Management proved insufficiently able to quantify the effect of turning the dials on performance, risks and costs. We, therefore, devised a risk-based method to examine and assess assets much further into the future than six years, with an infinite maintenance horizon”, he explains. “This enables us to optimise maintenance over the assets’ entire lifespan with regard to the triangle mentioned earlier.”
Multi-year maintenance planning
Kees-Willem Markus is a RAMS (Reliability, Availability, Maintainability, Safety) and Asset Management Senior Consultant. He further developed the methodology with Arno for the Directorate-General for Public Works and Water Management under the name DREAM. DREAM stands for Data-Driven Risk-Driven Enterprise Asset Management. Kees-Willem explains: “DREAM is a method that cleverly combines the possible failure behaviour of structures, inspection and/or measurement results and maintenance advice with the help of an uncertainty analysis into a multi-year maintenance plan. As a result, the maintenance of assets and the required budget is predicted for the coming years, without unexpected hindrances resulting from malfunctions, necessary (unplanned) maintenance or structural failure.”
This method has been worked on for years. The basis of this development is the risk matrix that was used in the past. “We played around with that”, continues Kees-Willem. “Imagine: if you accept more risks, what is the effect? DREAM originated from the idea that we increasingly collect more and better data and perform better and more complete risk analyses.
Moreover, the DREAM method has been designed and developed in such a way that it also helps clients who have less affinity with figures. The long-term risk is indicated via colours (green, orange, red) for a range of areas and various maintenance and failure scenarios. This way, decision making can be substantiated and easily optimised for various maintenance budgets.