Security of Railway Infrastructures

In recent years, some sadly famous terrorist attacks that occurred in different countries have put into evidence that railway transportation systems are, on one side, not suitably protected, and, on the other side, not capable to tolerate and promptly react to them. Moreover, it is clear that such mass transportation systems are particularly attractive for terrorists, due to the potentially far-reaching, often “spectacular” results of attacks. Examples of such kinds of events are the New York (2001), Madrid (2004), and London (2005) terrorist attacks. In addition, by focusing on ground transportation networks and especially on railway systems, it is also easy to observe that they are particularly difficult to be secured since they are characterized by a high accessibility and a wide extension. In this sense, the needs of security and of mobility often conflict with each other. In effects, while an open and accessible system provides an efficient transportation of people and goods, this openness also allows malicious entities to exploit the transportation system as a target, weapon, or means to reach another target. Then, on the contrary, it is clearly evident that security actions taken to limit malicious adversaries from reaching their targets or to capture them may degrade the transportation system performances, and then they have to be designed with particular attention. This is the reason why worldwide institutions are more and more sensitive to the growing need for security of the so-called Critical Infrastructures (CI), such as railway transportation systems, and are adopting a number of regulatory measures. For what concerns scientific research, the efforts are intended to define methodologies, build risk mitigation devices, and find out best practices that are technologically advanced, soon achievable, reliable, so as to increase the infrastructure protection without affecting the relevant transportation system performances. In this framework, Quantitative Risk Analysis (QRA) represents the main methodological approach for assessing security, which is indeed often characterized by a large set of variables dependent on human sensitivity, and requires calibration and adaptive tuning, thus resulting into unfriendly tools for the non-skilled users. Then, in this chapter, to tackle with the problem of clarifying the aims, the characteristics, and the limitations, a general architecture for a possible QRA tool for railway security assessment is presented, with particular attention to the relevant specifications.