Performance Evaluation of Offa Garage Rotary in Ilorin, Kwara State, Nigeria

Abstract

Received: June/2024 Revised: October / 2024 Accepted: December / 2024 Published: December / 2024 This study evaluated the performance of the Offa-Garage rotary intersection in Ilorin, Kwara State, Nigeria. A rotary is a type of channelized intersection where vehicles are directed onto a one-way circulatory path around a central island. Observations and manual traffic counts were conducted every 15 minutes for one hour in the morning (7:00

Keywords: Roundabout, Traffic, Traffic Volume, Road Capacity, Offa Garage Traffic Delay. am to 8:00 am) and two hours in the evening (3:00 pm to 5:00 pm) over a five-day period from Monday, July 3rd to Friday, July 7th, 2023. The qualitative assessment of the roundabout's performance involves measuring delays, queue lengths, and the level of service. The analysis revealed that the highest traffic volumes and peak hour factors occurred between 7:00 am and 8:00 am. These times were selected for detailed analysis. The study employed a 12-step approach for rotary intersection performance analysis as outlined by the Highway Capacity Manual. It involved calculating entry capacities and approach capacities based on critical and follow-up headways using Gap-Acceptance parameters. The degree of saturation, delay, and queue lengths were also assessed to estimate the roundabout’s performance. The results showed that the performance level of the roundabout varied between service levels A and D. The degree of saturation, defined as the volume-to-capacity ratio, was used to determine these service levels for each approach and for the entire rotary intersection.