ALARP

In AS 2885 safety management studies the concept of ALARP used to be misunderstood fairly often (ALARP = As Low As Reasonably Practicable).  Some things ALARP is NOT:

  • A risk rank (does it appear in the risk matrix?)
  • The objective of the SMS (“We need to reduce all risks to ALARP”)
  • “We haven’t really tried to think of any mitigation so we’ll say risk is ALARP”

Unfortunately I’ve seen all of these as implicit interpretations of what ALARP means.

So where does ALARP fit into the AS 2885 SMS process?  It’s an extra step that is necessary if risk evaluation produces a risk rank of Intermediate:

  • Identify threats
  • Apply controls
  • Do the controls essentially eliminate the possibility of failure?
  • If failure remains possible, do risk evaluation:
    • High risk – unacceptable
    • Low risk – OK (more-or-less)
    • Intermediate – tolerable only if shown to be ALARP

If you are invoking ALARP in any circumstances other than to justify acceptance of an Intermediate risk you’ve got the concept wrong.

Risks that are Intermediate are in a grey area – higher risks are unequivocally unacceptable and so don’t take much thinking about (1), and lower risks can be tolerated just as they are so take even less thinking about.  But Intermediate risks are challenging because they are only borderline tolerable, and working out whether they can in fact be accepted may be difficult if you are honest about doing it properly.

More on how to asses ALARP in a day or so.

(1)  When I say High risks don’t take much thinking about, I mean within the safety management study.  They might create a very big problem for the pipeline engineer or manager who has to do whatever it takes to eliminate them, but that’s outside the SMS process until a solution comes back for reassessment.

Advertisements
This entry was posted in Risk assessment. Bookmark the permalink.

2 Responses to ALARP

  1. Chris Hughes says:

    At a recent SMS workshop in WA which was attended by a representative of the WA Regulator, he stated that the recent regulation changes in that state required ALARP to be demonstrated for ALL threats, even those fully mitigated by design and therefore not subject to an assessment against the matrix.

    • petertuft says:

      Chris,
      Any chance you could track down the relevant bit of the new WA regulations? It would be interesting to see exactly what it says and how that relates to AS 2885.
      My guess is it’s still based on a misunderstanding of the ALARP concept. When I said ALARP is not the objective of the SMS I should have gone on to say that that would be a very second-best outcome. What we really want to achieve (in order of priority) is:
      1. Threat fully controlled (failure eliminated)
      2. Negligible risk
      3. Low risk
      4. Intermediate risk and ALARP
      Maybe I really mean it’s the fourth-best outcome, so if it’s true that regulations require ALARP they aren’t necessarily asking for very much.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s