Comparative Study of Operational Performance between Roundabout and Signalized Intersection Using Sidra Software: A Case Study of Addis Ababa City

Abstract

Abstract: Traffic signals and roundabouts controls are commonly used in several at-grade junctions in urban areas for maximizing traffic efficiency and safety by separating traffic movements in time. The intersection performance is measured by comparing the parameters like- capacity, degree of saturation, delay, queue length, fuel consumption, operating costs and emission, etc. This research paper provides a comparative study of operational performance between a roundabout and signalized intersection at Gergi-Imperial. The traffic data on all approach of the intersection were collected by video camera during the most congested days of the week. The traffic volume obtained in different classes of a vehicle was converted to uniform vehicle fleet by the passenger car equivalency factor. The geometric data for the selected intersections were measured manually. Data analysis and processing were performed using SIDRA (Signalized and Unsignalized intersection Design and Research Aid) intersection software to compare the traffic flow condition at the intersection. The performance measures such as Average delay, Degree of saturation and Level of service at each intersection were interpreted for comparison. The capacities of the signalized intersection were found to be higher than the capacities of roundabout. Signalized intersection was found to be better than the roundabout in terms of the degree of operational performance. Keywords: Average delay, Intersection Capacity, SIDRA Software, Level of Service (LOS), roundabout, Signalized Intersection, Degree of Saturation