Factors influencing lane choice behavior on Addis Ababa–Adama Expressway: Multinomial logit modeling evidence from Ethiopia

Purpose. This study investigates factors influencing lane choice behavior on the Addis Ababa–Adama Expressway, Ethiopia’s first controlled-access highway, to provide empirical evidence for transportation planning and highway design in sub-Saharan Africa, where such research is absent. Methodology. Video-based observational data were collected at five strategically selected sites across the 80-kilometer expressway corridor. A total of 45,924 vehicle observations were extracted through frame-by-frame manual analysis capturing lane choice, vehicle characteristics, traffic flow parameters, and lane-changing behavior. Multinomial logit models were developed for each site-direction combination (10 models in total) to quantify the relationships between explanatory variables and lane-choice probability, with Lane-3 serving as the reference category. Results. Analysis revealed a pronounced middle-lane bias, with 55.5% of traffic concentrated in Lane-2, while Lane-1 and Lane-3 received 24.7% and 19.1%, respectively. Average Speed Ratio exhibited consistently positive associations with outer lane selection (odds ratios: 3.01–66.19). Passenger cars demonstrated 3.00–60.14 times higher odds of selecting outer lanes compared to trucks, reflecting systematic vehicle stratification. Lane position of preceding vehicles showed negative associations (odds ratios: 0.12–0.36), indicating platoon avoidance behavior rather than following tendencies. Lane Utilization Factor demonstrated self-reinforcing effects exclusively for middle-lane selection. Theoretical contribution. This research provides the first empirical validation of utility-maximizing lane choice theory in sub-Saharan African expressway contexts, documenting platoon avoidance behavior and self-reinforcing lane utilization patterns with implications for traffic simulation model calibration. Practical implications. Findings inform lane-specific pavement design standards, capacity analysis methods that incorporate vehicle stratification effects, and traffic management strategies, including variable message signs and targeted enforcement, to improve operational efficiency and safety on Ethiopian expressways. Sustainable Development Goals (SDGs): SDG 3: Good Health and Well-being; SDG 9: Industry, Innovation and Infrastructure – Developing quality, resilient infrastructure; SDG 11: Sustainable Cities and Communities