Construction of a Microcontroller-Based Automatic Traffic Light Controller for Reducing Congestion at Intersections in Ibadan

Background: Traffic congestion at urban intersections in Ibadan, South West Nigeria, contributes to economic losses, fuel wastage, and road accidents. Fixed-time traffic light systems are inadequate for dynamic traffic volumes. Aim: This project designed and constructed a microcontroller-based adaptive traffic light controller for application at a busy intersection in Ibadan. Methods: An ATmega16 microcontroller was programmed to implement a density-adaptive timing algorithm using infrared vehicle-detection sensors at each lane. Timing intervals were dynamically adjusted based on detected vehicle queue lengths. Proteus simulation validated circuit functionality before hardware prototyping. The prototype was evaluated in a simulated traffic environment. Results: The adaptive controller reduced simulated average vehicle waiting time by 34% compared with a fixed-time reference controller. Lane clearance efficiency improved by 28%. The system maintained reliable sensor detection up to 12 metres. Conclusion: The adaptive traffic light controller is technically feasible and demonstrates meaningful congestion reduction potential. Field deployment studies at actual Ibadan intersections are recommended, with integration of real-time remote monitoring for traffic management authorities. Keywords: traffic light controller, microcontroller, traffic congestion, adaptive timing, Ibadan.