5. Conclusion

The LOPA method is well-suited to the implementation of multiple safety barriers. It can be used to describe the chronological sequence of a scenario, and to identify all the technical, human and organizational barriers needed to reduce its criticality. It was initially developed to deal with scenarios defined by a single initiating event (cause)/consequence pair.

After some twenty years in use, feedback shows that the LOPA method is sometimes used to deal with accidents that may result from multiple scenarios. Users of the LOPA method should be aware of its limitations, and of the fact that there are other quantification methods more suited to the analysis of complex accidents (fault trees, event trees or bow ties).

The simplicity of use of the "original" LOPA method is undoubtedly its main advantage, but also the main pitfall to its successful...