Optimizing security vis-à-vis terrorist attacks. An application for public rail transport systems

study RiKoV deals with mitigating risks of a terrorist attack against the German public railway system. The research method and first results will be presented and discussed in this paper. In the project, a scenario-based risk assessment method was developed tailored to intelligent, rationally acting attackers. We consider risk as a function of the system’s vulnerability, the threat to the system, and the consequences of an attack. In particular, we apply three complementary ways to deal with the problem of fundamental uncertainty with respect to the terrorists’ motivation. In a first approach, the input parameters “intention” and “capability” are regarded as fuzzy parameters which are measured in qualitative categories. The second approach is the derivation of optimal rules in a multi-criteria framework for decisions under uncertainty. Finally, we complement our elaborated risk analysis with game-theoretic arguments.