Simulation Analysis of Traffic Management in Roundabout Systems

Urban transport systems incorporating roundabouts often confront substantial difficulties, notably when vehicles entering the roundabout fail to maintain appropriate gaps with those in the circulating lane. To address such challenges, we suggest utilizing a cellular automata model, specifically the Nagel-Schreckenberg (NaSch) framework, for evaluating the flow dynamics within single-lane roundabouts governed by traffic sig-nal coordination. We explore two distinct operational conditions: firstly, a scenario wherein vehicles on the approach adhere to established precedence rules; secondly, a condition under which traffic signals dictate the flow. Simulation studies reveal that the first condition gives rise to a triphasic traffic flow pattern characterized by free flow, jammed, and maximum current phases. Notably, an increase in the number of vehicles ignoring the requisite safety gaps upon entering the roundabout diminishes the throughput of the circulating lane. Conversely, in the second condition, traffic light implementation modulates the flow phases within the roundabout system. Although the extent of the free-flow phase remains stable, the capacity during maximum current conditions intensifies. However, congestion phases are observed in all lanes of the roundabout. Furthermore, the variability in the timing of traffic signals, specifically the alteration between green and red phases, significantly affects the system's overall efficiency.