The dynamic assignment of users has been widely studied for the road network while it is less considered for multimodal networks. In this article, we investigate the dynamic assignment of users in multimodal transportation systems while differentiating between informed and uninformed users. The problem is modeled as a multiagent system where we consider all of the modes that share the road infrastructure (private vehicles, taxis, buses, tramway, electric car sharing services), thus the users and vehicles of each mode are represented by an agent. As mentioned in the above, we consider two types of users: informed and uninformed. Our objective is to assess the impact of the presence of informed users on the dynamic assignment on the network. To do so, we provide an analytical study on the Braess paradox where we explore the possibility of improving the assignment of users through the information that is provided to them. The simulation model is cellular automata based and was executed on a multilevel network that includes a Braess paradox in order to validate the analytical results.