Added value in fault tree analyses

It is recognized that the usual output of a fault tree analysis in some studies is not sufficiently informative. For added value in a widely used instrument for doing risk analyses, a Markovian approach is suggested. It is shown how to extend the calculations of the standard fault tree gates, so that information is available not only on the failure probability at the top level, but also on estimates of its rate of failure and mean down time. In applying this to an integrated fault tree analysis of a municipal drinking water system, we further identified the need for gates that are variations of those currently in use