A Simple Real-Time Traffic Light Control System using PLC

This paper presents a simple real-time traffic light control method using the PLC model CP1L-M30DR-A. The control system can be operated and monitored through the HMI model EA043A. The traffic light control model represents a simple intersection with a single lane road, featuring traffic flow in four different directions. Each direction is equipped with a single traffic light. Initially, the duration of the green traffic light for all four directions was set at 30 seconds, with the option to extend it to a maximum of 90 seconds. On each road, two inductive proximity sensors were installed to measure the density of passing vehicles and the numbers of vehicle waiting at red traffic lights. The collected data is transmitted to PLC to calculate the green traffic light duration. Specifically, when the traffic density exceeded 15 cars, the duration of the green traffic light was extended by 1.6 seconds per car. The results obtained from the real-time control test proved to be accurate.