Design and Implementation of Intelligent Traffic Control System using Programmable Logic Controller

Generally, traffic light systems are regarded as open loop control systems, that is, they are in continuous operation without any form of feedback that can help the system take a decision based on certain conditions. And so, this is specifically part of the reason why there exist high vehicular densities at roundabouts. Having considered in providing a solution to this problem, this project integrated a 4I/O Programmable Logic Controller (PLC) into the traffic light system circuitry which provided feedback based on signals received from the input sensors connected to the PLC. When these sensors get energized due to the presence of a vehicle, it sends an ON-bit signal to the PLC through the input port terminating the sensor and the PLC. This signal in turn triggers the output port mapped in the microprocessor so that it energizes the Light Emitting Diodes (LEDs). During simulation, two forms of control were used: Primary (default) and Secondary control systems. On the secondary control, the PLC receives signal from the ultrasonic sensor on road tracks A and B then allows long queued vehicles to pass while it stops vehicular movement on road track C and D and vice versa. It is identified that this method of traffic light control has helped to ensure orderliness and evenly distributed vehicular flow at case study roundabout.