Control of large-scale traffic networks

Pietro Grandinetti

The talk focuses on traffic lights control in large-scale urban networks. We starts off with a study of macroscopic modeling based on the Cell Transmission model and we formulate a signalized version of such a model, in order to include the traffic lights description into the dynamics. Moreover, we introduce two simplifications of the signalized model towards control design, one that is based on the average theory and considers duty cycles of traffic lights, and a second one that describes traffic lights trajectories as binary signals. We use numerical simulations to validate the models with respect to the signalized Cell Transmission model, and microsimulations (with the software Aimsun), to validate the same model with respect to realistic vehicles’ behavior. Then, we propose two control algorithms based on the two models above mentioned. The first one, that uses the average Cell Transmission model, considers traffic lights duty cycles as controlled variables and it is formulated as an optimization problem of standard traffic measures. The second proposed approach is an optimization problem in which the decision variables are the activation and deactivation time instants of every traffic lights. We analyze via numerical simulations the convergence speed of the iterative algorithms, their computational burden and their performance regarding traffic metrics. Lastly, we present a study of the traffic lights control algorithm that is employed in several large intersections in Grenoble (France). We detail the technological and methodological differences with our proposed approaches and create into the microsimulator Aimsun the scenario representing the related part of the city, also reproducing the control algorithm and comparing its performance with the ones given by one of our approaches on the same scenario.

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