MODELING HUMAN ERROR RATES FOR HUMAN RELIABILITY-ANALYSIS OF A STRUCTURAL DESIGN TASK

It is generally accepted that human error, particularly in design, causes a significant proportion of structural failures. It is necessary to understand the 'micro' (or single task) behaviour of human errors before the entire system can be modelled. Reported herein is a description of proposed mathematical models of error occurrence that are suitable for use in a Human Reliability Analysis (HRA). These models may be used to provide error rate information. These models are fitted to realistic error occurrence data. The data was obtained from practising professional engineers and the tasks performed were cognitive; namely, calculation, table look-up and ranking tasks. These tasks are commonly encountered in typical design calculations. It was found that error occurrence behaviour is characterised by variation of error rates between individuals and, to a lesser extent, correlation of error rates for individuals. The effect of response time and experience were also examined. A comparison of the effect on structural reliability (for a typical structural design task) for error occurrence (based on the proposed models) is also reported.