Determination of Follow-Up Headway of Local Drivers at Urban Multilane Roundabouts in Gombe Metropolis

Accurate estimation of follow-up headway is fundamental for the operational analysis of urban roundabouts, especially in regions with heterogeneous traffic. This study presents a field-based approach to determining follow-up headway at three typical multilane roundabouts in Gombe metropolis, Nigeria, utilizing unmanned aerial vehicle (UAV) video surveys and rigorous manual data extraction. The 50th percentile method was applied to determine operational headway values for each roundabout. The results indicate a mean follow-up headway of 2.01 seconds, with site-specific values of 2.02 seconds (Central Roundabout), 2.20 seconds (Dukku Park Roundabout), and 1.80 seconds (Union Bank Roundabout), reflecting the combined influence of local geometry, driver behavior, and traffic composition. Variability between the sites highlights the importance of local context, as geometric complexity and the traffic characteristics affect headway selection. These findings reinforce the limitations of adopting foreign default values for capacity analysis in Nigerian settings. The study recommends adopting locally measured parameters in the capacity analysis of roundabouts with simulation and analytical tools such as the Highway Capacity Manual Models. The empirical results provide evidence-based direction for roundabout design and policy in rapidly urbanizing African cities.