1693 Figure 2 – Analysis of the USA MSHA fatal vehicle incidents for surface mining operations. Percentages indicate proportion of incidents where the failure of the control was identified as a contributing factor. 4. REAL-TIME ANALYSIS OF CONTROL EFFECTIVENESS Further work has been performed to explore if the methodology used to analyse criticality of controls from incident analysis can be extendable to deliver trend analysis of control effectiveness. For this analysis control effectiveness is defined as a combination of the reliability of the control (i.e. the degree to which the control is implemented and working as required) and the efficacy of the control (i.e. the ability of the control to prevent an unwanted event or mitigate the fatal outcome) as shown diagrammatically in Figure 3. The reliability of prevention controls can be derived from verification data if, and only if, verification questions and answers can be analysed to answer “when workers are exposed to hazard was the control implemented in a manner that it “of itself” protected the worker and was it working as required. For example, a control that protects workers working at height is the “correct use of fall arrest/restraint systems”. However, many verifications check anchor points, harness and lanyard condition and workers’ understanding but not whether workers at working at height are protected by the “correct use of fall arrest/restraint systems”. In some case disaggregated control questions can be analysed using Boolean logic to derive a measure of control reliability but in other cases this is not possible. Reliability of mitigation controls can sometimes be derived from verification data in the same way that the reliability of prevention controls can be derived. However, for other mitigation controls this can be challenging if the mitigation control requires the unwanted event to occur for the reliability of the control to be determined. For example, reliability of emergency response to attend to injured persons should be assessed
RkJQdWJsaXNoZXIy MTM0Mzk2