If the new risk assessment methods produce results similar to QRA, why not just use classic QRA?

Several reasons, classic QRA is expensive and awkward to apply to a long, linear asset in a constantly changing natural environment – can you imagine developing and maintaining event trees/fault trees along every foot of every pipeline? The classical QRA was created by statisticians and relies heavily on historical failure frequencies. Ask a statistician how often something will happen in the future and he will ask how often it has happened in the past. I often hear something like, “we can’t do a QRA because we don’t have data”. I think what they mean is that they believe that databases full of incident frequencies – how often each pipeline component has failed by each failure mechanism – are needed before they can produce QRA-type risk estimates. That’s simply not correct. It’s a carryover from the notion of a purely statistics-driven approach. While such historical failure data is helpful, it is by no means essential to RA. We should take an engineering and physics-based approach, rather than rely on questionable or inadequate statistical data. Ignoring the underlying scientific principles in a pipeline failure scenario makes the assessment incomplete.