Applying the Behavioural Approach to Safety

1 Safe working behaviours are defined and a checklist of about 20 such safe practices is set up. 

2 Volunteers from the work group involved in the study make random checks using the list to establish the present level of safe and unsafe working practices (the baseline). 

3 This is shown to the group, who review their performance and set goals or targets for improvement. 

4 Measurements continue for a further period of from 12 to 16 weeks, with continuous weekly feedback to the group. During this time safety behaviour invariably improves towards, or can even exceed, the target set. 

5 At the end of this period the checklists and the goals are reviewed and updated and the cycle starts again. Usually at this stage new observers take over so that, over time, all members of the work group take part in the process. 

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The lessons from the above considerations may now be applied to the introduction of a behavioural system of safety. The behavioural approach, as will be seen in the next chapter, concentrates not on generalities, but on encouraging specific behavioural change. It also places control of the scheme in the hands of those who are most directly affected - those doing the job. This twin-pronged approach has direct, and indirect, effects on the various elements of the model. 

The design is based on the maximum shear stress which occurs at the end of the joint. However, the shear stress decreases rapidly within a short distance from the Joint end. It should also be noted that this peak stress occurs immediately after a load is applied, but owing to the viscoelastic nature of polymer adhesives, this peak flattens in the course of time. This behaviour is shown in Figure 5.32, based on the work of Groth (reference 5.36). This viscous behaviour further increases the margin of safety in the design approach. 

In the past it has been irsual for the safety practitioner to concentrate much effort on the hazard and the methods by which it can be removed or controlled. This approach has been very sirccessfirlfy applied in industry, but the irrjrrry causation model now provides the safety practitioner with another new field of investigation in determining the reasons for human error. The human error is not considered to have arty element of blame. What is important is to determine the cause of the human error and to identify the stimtrlus that produced the behaviour pattern which resulted in the error. 

Early laboratory and field study work carried out by Adam and Scott (1971), Adam (1975), McCarthy (1978) and Kim and Hammer (1976) had already demonstrated the potential of behaviour modification techniques in a quality improvement process. These studies, however, tended to focus on specific, time-bound experiments within a particular setting or occupation. We were much more interested in applying a behaviour-based approach within a plant operating a continuous production process, involving several departments, and consisting of multiple skills and skill levels. So, it seemed to us that quality behaviour, unlike safety behaviour, would be contingent on interactions with other people and we would need to optimize... 

Abstract. Modern safety-critical systems are increasingly reliant on software. Software safety is an important aspect in developing safety-critical systems, and it must be considered in the context of the system level into which the software wiU be embedded. STPA (System-Theoretic Process Analysis) is a modern safety analysis approach which aims to identify the potential hazardous causes in complex safety-critical systems at the system level. To assure that these hazardous causes of an unsafe software s behaviour cannot happen, safety verification involves demonstrating whether the software fulfills those safety requirements and will not result in a hazardous state. We propose a method for verifying of software safety requirements which are derived at the system level to provide evidence that the hazardous causes cannot occur (or reduce the associated risk to a low acceptable level). We applied the method to a cruise control prototype to show the feasibility of the proposed method. 

In laboratory studies of human behaviour error is commonly used as an index of performance. A common finding in these studies is the marked trade-off between the speed of response and number of errors made. An example of this trade-off is shown in Figure 23.3. It is interesting to note that many of these approaches have been incorporated into concepts of human error as they apply to considerations of safety. 

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