Design of a Real-Time Traffic Light Controller with Adaptive Timing for Busy Intersections in Abuja

Fixed-cycle traffic signal systems at busy intersections in Abuja, Federal Capital Territory, cause significant vehicle queuing during peak hours because they do not adapt to real-time traffic density variations. This project designed a real-time adaptive traffic light controller that adjusts green phase durations based on live vehicle queue length detection using infrared sensor arrays. Four STM32 Nucleo microcontrollers were interconnected via CAN bus to manage a four-phase intersection with pedestrian crossing signals. Each lane was equipped with three IR beam sensors at 5-metre intervals to estimate queue length. The adaptive algorithm extended the green phase for the busiest lane up to a maximum of 60 seconds and reduced it for low-traffic lanes to a minimum of 10 seconds, while maintaining a fixed amber phase of 3 seconds. Hardware failsafe logic defaulted to a fixed 30-second cycle if any sensor failed. The system was simulated using hardware-in-the-loop testing with vehicle queue inputs emulated by a MATLAB Simulink traffic flow model using Abuja's Area 11 intersection geometry. Simulation results showed a 28.6 percent reduction in average vehicle waiting time and a 21.3 percent reduction in estimated intersection delay compared to fixed-time operation under simulated peak-hour traffic conditions. Pedestrian phase conflicts were entirely absent in all 1,000 simulated cycles. The study recommends physical deployment at the Berger Roundabout as a pilot test site in collaboration with the Federal Capital Development Authority's transport department.

Keywords: adaptive traffic control, microcontroller, queue detection, Abuja, intelligent transport system