Collaborative Ramp Metering Control: Application to Grenoble South Ring

The thesis presents the results of research on distributed and coordinated control method for freeway ramp metering. The freeway traffic is represented by the Cell-Transmission Model. The primary control objective is to provide a uniform distribution of vehicle densities over freeway links. Density balancing is a new traffic objective which can potentially reduce the number and intensity of acceleration and deceleration events and therefore, it can make a travel more safety and comfortable while decreasing fuel consumption and emissions. In addition, the objective takes into account standard traffic metrics like Total Travel Distance and Total Travel Spent. For the controller, a distributed modular architecture is assumed. It enables to compute the optimal decisions by using only local state information and some supplementary information arriving from the neighbouring controllers.The contributing part begins with the analysis on equilibrium sets of the Cell-Transmission Model. The goal of this study is to derive the conditions that assure the existence and the uniqueness of the balanced equilibrium states. The next step is to find a set of inputs such that the resulting equilibrium state is balanced. In the set of balanced equilibria, we are interested in the selection of the point that maximizes the Total Travel Distance. In the sequel, the implementation aspects and limitations of the proposed method are discussed. Finally, several case studies are presented to support the analysis results and to examine the effectiveness of the proposed method.The major part of the thesis aims on a design of an optimal controller for balancing the traffic density. The optimization is performed in a distributed manner. By using controllability properties, the set of subsystems to be controlled by local ramp meters are identified. The optimization problem is then formulated as a non-cooperative Nash game. The game is solved by decomposing it into a set of two-players hierarchical and competitive games. The process of optimization employs the communication channels matching the switching structure of system interconnectivity. The alternative approach of balancing employs the theory of multi-agent systems. Each of the controllers is provided with a feedback structure assuring that the states within its local subsystem achieve common values by evaluating consensus protocols. Under these structures, an optimal control problem to minimize the Total Travel Spent is formulated. The distributed controller based on the Nash game is validated via Aimsun micro-simulations. The testing scenario involves the traffic data collected from the south ring of Grenoble.