The aim of this chapter is to develop models for network-level traffic systems and, moreover, to design feedback controllers for network-level traffic problems in user-equilibrium as well as system-optimal settings. In order to do so, the chapter develops the network-level traffic dynamics for the traffic assignment problem and also shows the objective functions for the user-equilibrium and the system-optimal cases. Link-based and route-based models are presented from literature. Dynamic traffic assignment problem is formulated in the structure of an H∞ control problem, so that the solution techniques available for the controller can be applied to the traffic assignment problem. A sample problem is presented and control design steps for that problem are presented.