Analysis of Capacity of Roundabouts Based on Geometric Design (Case Study: Isfahan Roundabouts Azadi Square)

Today, roundabouts are one of the safest and most used intersections in the world, which are designed and implemented according to different traffic conditions. The roundabout capacity is influenced by different factors such as geometry. There are different methods for calculating roundabout capacity, which today simulation is used as an acceptable one. The Aimsun simulating software as a microscopic software is used to analyze traffic networks. In this research, this software is used to simulate the geometry of the Azadi Square in Isfahan. According to the results obtained from the software outputs and the implementation of the original model with real conditions, various geometric design options have been proposed to increase the roundabout capacity. Then, delay time, travel time, density and speed were selected as criteria for comparison of options using analytical hierarchi process (AHP). According to the results, the non-level intersection variant in the east-west direction while retaining the roundabout, were selected as the preferred variant.