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

Abstract

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.

Multi-hazard Approaches to Civil Infrastructure Engineering

“…The preferred method of attack is improvised explosive devices (IEDs). An IED is relatively simple to design and manufacture if done by well-trained personnel, resulting in reliabilities in excess of 90 % (Grant and Stewart 2012). However, the probability of an IED creating a damaging effect (damage in excess of $1 million or attack resulting in casualties) reduces to 23 % for terrorists in Western countries where there is less opportunity for IED operational skills to be acquired (Grant and Stewart 2015).…”

“…This was clearly evident from the second attack on the London Underground on 21 July 2005 where four IEDs failed to initiate and in Glasgow International Airport in 2007 and Times Square in 2010 where vehicle-borne improvised explosive devices (VBIEDs) failed to initiate. The probability of successful attacks using IEDs increases to 65 % for terrorists or insurgents in the Middle East (Grant and Stewart 2012). …”

A risk and cost–benefit analysis of police counter-terrorism operations at Australian airports

“…Threats 1 and 2: In principle, an IED is relatively simple to design and manufacture if done by well-trained personnel, resulting in reliabilities in excess of 90 percent (Grant & Stewart, 2012). However, the probability of an IED creating a damaging effect (casualties) reduces to 19 percent for terrorists in Western countries where there is less opportunity for IED operational skills to be acquired (Grant & Stewart, 2012).…”

“…However, the probability of an IED creating a damaging effect (casualties) reduces to 19 percent for terrorists in Western countries where there is less opportunity for IED operational skills to be acquired (Grant & Stewart, 2012). This was clearly evident from the second attack on the London Underground on 21 July 2005 where four IEDs failed to initiate, and Glasgow international airport in 2007 and Times Square in 2010 where VBIEDs failed to initiate.…”

“…This was clearly evident from the second attack on the London Underground on 21 July 2005 where four IEDs failed to initiate, and Glasgow international airport in 2007 and Times Square in 2010 where VBIEDs failed to initiate. The probability of successful attacks using IEDs increases to 65 percent for terrorists or insurgents in the Middle East (Grant & Stewart, 2012). It should also be noted that, since 9/11, terrorists in the USA have been able to detonate bombs in A risk and cost-benefit analysis 103 only one case (in Boston in 2013) and the same holds for the UK (the bombings of London transport on 7 July 2005).…”