In the Netherlands hydraulic engineering structures are not only designed, but are also managed and maintained (M&M). In the nineteen-nineties in the United States during periods of high water scores of bridges collapsed, because American law forbids the use of bed protection around bridge piers and moreover, no maintenance plans were available. Despite the fact that in Korea there are always strong tides recently during periods of high water, various bridge piers and abutments have been undermined with dramatic consequences. This emphasises the need for good M&M plans for both bed and bank protection. This publication contributes to the International Conference on Scour and Erosion (ICSE-3) in Amsterdam (1 -3 November 2006) and contains information on the loads imposed on bed protection by currents and on the amount of damage that may occur in normative situations