Conceptual Approach of Hybrid Meso/Micro Simulation and Its Implementation for Traffic Signal Management Systems for Large Scale Networks

The evaluation of advanced traffic signal systems requires a network-wide assessment of their impact as opposed to an isolated analysis of key intersections. Microscopic traffic simulation models emulate the dynamics of individual vehicles in a detailed network representation, based on car-following, lane changing, gap acceptance models; include route choice models to implement dynamic traffic assignment; and account explicitly for traffic control. Microscopic models are usually appropriate for operational analysis due the detail of information provided by the simulator. However, they are data intensive and have a significant computational cost. Mesoscopic models combine simplified flow dynamics with explicit treatment of interrupted flows at intersections and allow modeling of large networks with high computational efficiency. However, the loss of realism implied by a mesoscopic model makes it necessary to emulate detailed outputs; for instance, detector measurements or instantaneous emissions. The above give rise to the need to combine meso and micro approaches into new hybrid traffic simulators where very large-scale networks are modeled mesoscopically and areas of complex interactions benefit from the finer detail of microscopic simulation. Combining an event-based mesoscopic model with a more detailed time-sliced microsimulator raises consistency problems on the network representation and the transitions meso-micro-meso. This paper discusses these problems, proposes a solution and illustrates how it works in practice.