Wide Scattering of Nagel-Schreckenberg Fundamental Diagram Under Traffic Bottlenecks

Abstract

Based on current traffic flow studies, there are several traffic cellular automaton (TCA) models, in which the wide scattering of flow-density data are observed. In this study, we propose that the physical mechanism behind the observed wide scattering is the variability of cluster formation in congested traffic. By simulat- ing road bottlenecks on highways using the Nagel-Schreckenberg (NaSch) model, varying degrees of wide scattering is observed. Numerical analysis of the results shows a strong correlation between the variance in the number of clusters and the width of scattering in the flow-density data. By studying the microscopic dynam- ics of the NaSch model, we proposed the physical mechanism of wide scattering in TCA models to be the heterogeneity of cluster formation in congested traffic flow. In addition, the results were compared with Tian (2012)’s Average Space Gap Model (ASGM) and through qualitative analysis, we suggest that the wide scattering observed is due to the AGSMmechanism favouring statistically unfavourable cluster configurations.