Optimal Location of Security Devices

The design of a security system, in terms of number and position of the security devices composing it, is one of the main issue tackled in METRIP project (MEthodological Tool for Railway Infrastructure Protection). It is a complex problem where a very large set of configurations has to be explored in order to determine the most efficient one, which guarantees the highest protection level. Indeed a good placement of the devices has to satisfy two main targets. On one side it has to guarantee the highest security level, i.e. it has to be able to control the widest achievable area. On the other side, it has to be economically sustainable, i.e. it has to be realized with acceptable costs. In literature this problem is generally referred to as sensor placement problem, widely treated by integer linear programming models and combinatorial optimization methods. In this chapter we will present the main covering models present in literature and adopted in METRIP project for the placement of devices preventing the malicious intrusions in railway assets, with particular reference to the intrusions in a railway station. The applicability of these models will be proved using two test cases which represent two typical railway asset schemes.