Modern distributed systems tend to integrate more and more features and components that increase their complexity and size. This often leads to the decomposition of such systems into multiple parts to overcome the complexity of their modeling and analysis. In this paper, we present a modeling methodology for systems engineering based on a modular approach. The methodology relies on the definition of components and assembling rules to model complex systems. It is founded on formal specification formalisms and tools to enable model checking. This paper proposes an example by which we apply this methodology on a complex system from the domain of Intelligent Transport Systems.