Evaluating the performance of Antar bin Shaddad signalized Roundabout in Baghdad city

In some roundabouts, the risk of blocking off or creating a long queue is likely happening when a roundabout suffers from high traffic or unbalanced flow patterns. The applying of signalization in roundabouts as treatment or replacement can be useful for such a problem, especially during peak rush hours. The purpose of this study is to examine the performance and flexibility that signalized roundabout offers in handling traffic operation in Baghdad city. Antar Bin shadad signalized roundabout are simulated using VISSIM simulation software to compare the signalized roundabout performance with other different alternative modes such a signalized roundabout with optimum cycle time, signalized intersection, metering system. The simulation results have been analyzed, compared with field collected data, and evaluated. Depending on circulating volumes and the geometric design configuration of each roundabout, it has been found out that, the best suggested scenario for the studied roundabouts (signalized roundabout, signalized intersection and meter roundabout) that could handle the current traffic volumes of all the studied roundabouts is the signalized roundabout scenario with optimum cycling time. In Antar signalized roundabout and from observed simulation results, the best location for an over pass or under pass is to separate the traffic generating from ESB from intersecting with other approaches upstream, this improvement can reduce the delay of the entire roundabout at peak hour by 26%. Keywords: roundabout, VISSIM, Antar Bin shadad, simulation