Management of complex systems (such as hospitals, cities, transportation systems) is concerned with many problems, among which the impact evaluation of a decision is. To do so, we propose that the decision maker interacts with a model of the organization. This action is similar with a player's one and makes possible immersion of the decision maker in a virtual environment rather close to the real environment. Thus environment objects must be able to react as realistically as possible. Within an Urban Traffic Systems that leads to produce a modeling and simulation environment with "SimCity©"-like graphics but with some advanced functionalities added for the design of networks and the management of the traffic. The graphic aspect has a huge importance within this domain. We propose to solve this problem using an approach that combines the facility of object oriented modeling with the power of behaviors description of the multiagent approach. This methodological framework includes the use of formal specifications enabling a model checking before its implementation.