Comparative Assessment of Urban Intersection Performance under Varying Traffic Demands in Ilorin, Kwara State, Nigeria

Abstract

Abstract: Efficient operation of urban intersections is fundamental to achieving safe, reliable, and sustainable mobility in modern cities. This study evaluates the operational performance of eleven major intersections in Ilorin, Nigeria, comprising roundabouts, four-legged, and three-legged junctions. The study pursued two objectives, which are to assess the influence of geometric design characteristics and approach-specific traffic flow patterns on intersection performance and to compare the operational efficiency of different intersection types under peak traffic conditions. Field data were collected over a seven-day period using continuous video recording, capturing key geometric and traffic parameters including lane width, turning radius, turn-bay length, and approach volumes. These data were analysed using manually applied [2] procedures to estimate average delay, queue length, and level of service (LOS). Results indicate notable performance variations among intersection types. Roundabouts exhibited comparatively better operational performance, operating within the [2]-defined LOS D range with an average control delay of 37.3 seconds per vehicle. Four-legged intersections showed moderate performance, while three-legged intersections experienced the highest delays (mean = 51.2 s) and queue lengths extending up to 70 m. Statistical analyses using one- way ANOVA, Tukey’s HSD, and regression modelling revealed significant differences in delay across intersection types (p < 0.05). Although the chi-square test indicated a weak association between intersection form and LOS classification, the overall findings suggest that, under the observed traffic and geometric conditions, roundabouts demonstrate greater operational resilience. Accordingly, the adoption of roundabouts is recommended as a traffic management measure tailored to comparable urban settings in developing regions, rather than as a universally applicable solution