Performance Evaluation of a Hybrid Roundabout Using a Microscopic Simulation

Roundabouts are one of the safest types of intersections. There are a number of roundabout types in literature. Each roundabout type is distinguished by some characteristics. To design more efficient junctions, hybrid roundabouts can be created by combining their required characteristics geometrically. In this study, the safety feature of the turbo junction type and the easing up the traffic density feature of the hamburger junction have been combined. Some geometric parameters and layout details of the proposed hybrid roundabout are given, and its performance was simulated in a signalised 4-leg roundabout as the most frequently used intersection in Antalya. The performance of the proposed hybrid roundabout was compared with the status in 2016 and the current status in 2017 and beyond of the roundabout through AIMSUN transport simulation software. In regard to performance analysis, delay time, travel time, speed, density, fuel consumption, number of stops, queuing, carbon emission were analysed for all statuses and compared. In addition, traffic safety analysis has been performed for all statuses and compared. Results show that the overall average performance of the proposed roundabout increases by 40% and 41.8% in comparison with the statutes in 2016, 2017 and beyond, respectively. The proposed roundabout is 41% safer than the status in 2016, and the accident risk is lower by 18.5% than the current status.