Protection of environment implies the coordination of the local and regional authorities to implement actions for conservation of all natural resources in the actual context of globalisation. One of the most important direction for applying the above mentioned desiderates is a better planning of transportation, as we all know that globalisation implies an accelerated process of externalisation of ideas, know-how, products and labours. In this chapter, we consider discrete event systems (DES) modeled via a state space representation. The model objective is the avoidance of a given set of states, or equivalently the fact that certain predicates, specified in terms of states are always false. We address the state space controlled Petri Nets (PN) and a technique to reduce the complexity of these nets, by taking into account the fact that the complexity of the considered nets depends mainly on the representation of the control design, respectively on the forbidden sets of places. Our goal is to describe in an efficient way the forbidden sets of the modeled system, e.g. to describe in an efficient way the DES modeled with controlled Petri nets. An example from the railway systems illustrates this approach.
