A systems model for probabilistic risk assessment of improvised explosive device attacks

Due to their improvised nature, the variability in the design, manufacture and operation of most improvised explosive devices (IEDs) defy the traditional paradigms used to assess the effectiveness of conventional munitions. Thus, IEDs are complex socio-technical systems to model. To compensate for inadequacies in model design or data deficiencies, expert judgement and subjective probability assignments are often employed. The paper aims to reduce this reliance by developing an IED probabilistic risk assessment model using a systems model for IED attacks based on IED device reliability and characterising the human aspects of IED attack operational effectiveness from existing terrorism databases. This model can then be used to develop an automated model for IED probabilistic risk assessment that can be used towards informing military applications such as operations planning and war-gaming, and civil applications such as security risk management (including event planning), protective construction requirements, and insurance assessments. It was found that the risk of loss (fatalities, property damage) is influenced more by operational aspects (such as target selection, IED placement and attack timing) than the technical aspects of the device design and manufacture.