Conversion of Large Unsignalized Roundabout in Baghdad City to Signalized Intersection

Abstract Rapid population growth in Iraq has influenced all aspects of life, including transportation networks. The substantial population growth immediately coincides with an increase in the number of vehicles using the traffic networks. City roundabouts often experience significant traffic congestion, particularly during peak hours, necessitating the intervention of traffic police to control and alleviate the congestion. This indicates that the roundabout fails to operate as intended (facilitating the smooth and uninterrupted flow of vehicles). This study aims to convert a large unsignalized roundabout (Abdelkader El Jazairi Square) relatively close to the University of Technology campus to a signalized intersection. PTV VISSIM software was used as a simulation tool to design and evaluate the roundabout and the proposed signalized intersection. The evaluation concluded that Abdelkader El Jazairi Square operates at a level of service F, with an average control delay of 143.17 sec/veh and an average queue length of 203.03 m. Converting the roundabout to a signalized intersection resulted in a substantial reduction in delay and an improvement in the level of service. The signalized intersection significantly reduced vehicle delays by 74%. The LOS shifted from F to C. The reduction in queue length due to the conversion into a signalized intersection was 90%, resulting in better operational performance than the roundabout.