1. MODELLING SAFETY NZISM
Wayne Vernon
23 May 2016

3. Copyright James Reason

6. Safety management system Regulatory system
Chemical process
Control valve
u-Processor
Safety management system
Regulatory system
Production system
The New Zealand Economy
Software

8. accidents occur when
Control structure or control actions do not enforce safety constraints
Unhandled environmental disturbances or conditions
Unhandled or uncontrolled component failures
Dysfunctional (unsafe) interactions among components
Control structure degrades over time (asynchronous evolution)
Control actions inadequately coordinated among multiple controllers

9. Assumption 1
Safety is increased by increasing system or component reliability. If components or systems do not fail, then accidents will not occur.

10. New Assumption 1
High reliability is neither necessary nor sufficient for safety.

12. Assumption 2
Accidents are caused by chains of directly related events. We can understand accidents and risk by looking at the chain of events leading to the loss.

13. New Assumption 2
Accidents are complex processes involving the entire socio-technical system. Traditional event-chain models cannot describe this process adequately.

14. Assumption 3
Probablistic risk analysis based on event chains is the best way to assess and communicate safety and risk information.

15. New Assumption 3
Risk and safety may be best understood and communicated in ways other than probabilistic risk analysis.

16. Assumption 4
Most accidents are caused by operator error. Rewarding safe behaviour and punishing unsafe behaviour will eliminate or reduce accidents significantly.

17. New Assumption 4
Operator behaviour is a product of the environment in which it occurs. To reduce operator ‘error’ we must change the environment in which the operator works.

18. Assumption 5
Major accidents occur from the chance simultaneous occurrence of random events.

19. New Assumption 5
Systems will tend to migrate towards states of higher risk. Such migration is predictable and can be prevented by appropriate system design or detected during operations using leading indicators of increasing risk.
•Most major accidents arise from a slow migration of the entire system toward a state of high-risk (Jens Rasmussen)
–A socio-technical system is a dynamic process continually adapting to achieve its ends and to react to changes in itself and its environment
–Systems and organizations migrate toward accidents (states of high risk) under cost and productivity pressures in an aggressive, competitive environment
–Need to control and detect this migration
Systems analysis offers more effective ways of developing predictive measures than most other approaches.

20. Assumption 6
Assigning blame is necessary to learn from and prevent accidents or incidents.
In a classic case of cognitive dissonance, this slide applies to you, but not to me.
As long as society regards killing people at work as a crime, there will be a requirement for the regulator to put an argument before a court to apportion blame, and, where necessary, to inflict punishment.

21. New Assumption 6
Blame is the enemy of safety. Focus should be on understanding how the system behaviour as a whole contributed to the loss and not on who or what was to blame for it.
This statement implies that duty holders need to move away from the ‘blame the operator’ approach to the ‘what caused the operator to behave in that manner?’ approach.
•“Blame is the enemy of safety”
–Focus on “who” and not “why”
•“Root cause” seduction
–Believing in a “root cause” appeals to our desire for control
–Leads to a sophisticated “whack a mole” game
–Fix symptoms but not process that led to loss
–Same accident happening over and over again

22. Taken from: http://csrl. scripts. mit. edu/home/get_pdf. php

23. The HHU takes a three-pronged ‘Educate-Engage-Enforce’ approach to our work:
Educate stakeholders (industry bodies, operators, duty holders and their representatives) on their statutory duties by providing relevant information, advice and guidance
Engage with stakeholders to achieve positive health and safety outcomes, which includes encouraging the development of proactive management systems
Enforce compliance with the legislation through the use of regulatory tools.

24. Operators can expect inspectors to:
Focus on the effectiveness of workplace safety management systems and processes
Provide advice to duty holders and employees
Provide timely, consistent and transparent assessment of statutorily required information
Work directly with worker safety representatives
Consult with other health and safety inspectors and
Enforce the law using a range of enforcement tools such as Improvement Notices, Prohibition Notices, Infringement Notices or Prosecutions.

25. questions

26. references
BBC Knowledge dramatization of the eruption that wiped out the city of Akrotiri in approx BC Buncefield Investigation board. Columbia disaster Nancy Leveson’s book ‘Engineering a Safer World’ Tutorial on safe design containing oil well safety control structure: High Hazards Unit web page: Victoria University of Wellington course on systems thinking: