Abstract
An important challenge for homeland security agencies is to properly understand the interaction between terrorists and the methods to protect and deter attacks on the transportation network. Examining the nature of these interactions can greatly assist the enhancement of existing technologies and guide the development of new ones. This interaction is complex, possessing numerous variables that affect potential outcomes. This paper presents the Perception Square Interaction Cube Model (P 2 I 3 -Model) to describe these interactions using the system dynamics approach. This model incorporates three participants: the homeland security agency, the attacker, and the real world. The HS-Agency-perception, Attacker-perception, and Real-world submodels respectively characterize these participants. These three interacting sub-models combine to form the system governing the participants' perceptions, behaviors, and actions. The model accepts a set of measurable inputs from the HS agency and produces quantitative outputs to guide the HS agency's protection planning, deployment, and strategic policy revision activities. Simulation results suggest that the probability of attack success from the perspectives of the HS agency and attacker can differ significantly. System uncertainties and intelligence efforts are the central factors influencing these probabilities.