ALARP For Engineers: A Technical Safety Guide

The IMechE’s Safety and Reliability Group have created a new guide on a key topic in engineering: ALARP (As Low as Reasonably Practicable)

Changes to UK safety legislation have rendered much of the existing guidance on ALARP misleading. Any requirements for quantifying risk have been removed and guidance to the judiciary places stringent criteria for any such evidence, but to date this is not reflected in the guidance to engineers. Documents, such as the HSE’s ‘Reducing Risks, Protecting People’ have not been withdrawn or updated since these changes, leaving the impression that quantification of risk remains part of the Health and Safety at Work Act. 

These changes also affect the methodologies used to analyse risks. Predictive tools, such as risk matrices and QRA, are no longer applicable, so this new guidance proposes their replacement with more objective, scientific, and legally admissible methods.

This is a pan-industry document, which also encourages cross-fertilisation of specialist methodologies that may have a wider application. Although it is based on UK legislation, it should be good practice in any jurisdiction.

Key features:

  1. An explanation of the key legal obligations and admissible types of evidence.
    - the legal principles with some case law examples.
  2. A proposed ‘Proportionality Matrix’ to replace risk matrices.
    - to determine the level of analysis required.
  3. Detailed guidance on hazard identification.
    - a tiered approach, based on the foreseeable consequences.
  4. A comparison of common methodologies.
    - some lessons from Process Safety, the introduction of Systems Theoretic Process Analysis (STPA) and a systems approach throughout the full product lifecycle.
  5. An explanation of the technical and psychological pitfalls in risk prediction.


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