An MPC-driven VSL control of motorway traffic by employing a continuum second-order traffic model

Variable speed limit (VSL) system driven by model predictive control (MPC) is implemented as a proactive traffic control measure for effective and safer traffic flow operations. Conventionally, the application of the VSL control hinges upon the discrete second-order macroscopic models. Conversely, the MPC paradigm hardly ever employs continuum second-order models for traffic control. In this paper, an improved continuum second-order macroscopic model is used as a predictive model in VSL control driven on MPC. The VSL control is based on actual motorway traffic in Dublin, and is implemented in a microscopic traffic simulation. The findings of the study are two-fold: first, the predictive capability of the continuum second-order model is evaluated; second, the effectiveness of the MPC-driven VSL control strategy is assessed. Within this MPC paradigm, the motorway experience a significant reduction in traffic congestion. The efficacy of the proposed VSL control is demonstrated with a key performance index, flatness index (FI). FI of 0.77 and 0.72 is observed in the congested segments of the motorway, indicating moderate to strong improvement of traffic flow with the VSL control. In other words, 58% to 76% improvement is observed in the congested segments of the motorway. The proposed framework is vital for effective traffic control as it demonstrates the capability to alleviate congestion.