Risk aversion and decision-making for homeland security infrastructure protection

The use of decision theory to determine acceptability of risk is crucial to prioritise protective measures for built infrastructure. The paper will assess terrorist threats to critical infrastructure and the costeffectiveness of protective and counter-terrorism measures. In this paper, we focus on protection of airport civil infrastructure (ie. terminals). Decision-support criteria based on net present value (net benefit) and expected utility to consider risk aversion are described herein. This analysis will then consider threat likelihood, cost of security measures, risk reduction and expected losses to compare the costs and benefits of security measures to decide the optimal protective measures to airports. It was found that the attack probabilities, even of a massively destructive attack, had to be extremely high to justify protective measures on airports. However, if the decision-maker is particularly risk averse, expenditure on protective measures would be justified for attack probabilities of up to an order of magnitude lower, particularly if indirect losses of a terrorist attack are assumed to be extremely high. Overall, however, it is questionable whether special efforts to further protect airports are sensible expenditures of public funds