Transportation Network Risk Profile for an Origin–Destination Pair

Abstract

Transportation security and mobility often conflict with each other. An open and accessible system provides for the efficient transportation of people and goods; however, this openness also allows malicious entities to exploit the transportation system as a target, weapon, or means to reach another target. Security actions taken to prohibit malicious entities from reaching their targets or to capture them after an attack may degrade the transportation system. Security may also cause the entities to adapt their methods or targets and thus create more complex analysis requirements. This paper describes the incorporation of two types of substitution (method and target) into a methodology to determine the risk profile for the transportation system because of attacks on the transportation system itself, collateral damage to the network because of targeting of adjacent assets, and preevent and postattack security measure implementation. Monte Carlo simulation generated scenarios of target, attack methods, intelligence, security, substitution, target failure, and damage to the transportation network. Risk was then characterized through a profile of scenario likelihood and consequences. Application of the methodology to a hypothetical network with 5,000 iterations revealed one instance of no targets being selected. Although the scenario probabilities were very small, 18% of the cases resulted in the complete disconnection of the origin–destination pair. Thus, a city's decision makers should carefully consider the use of security measures in conjunction with the attacks if postattack evacuation is a potential action.