Optical feedback control system for fault-tolerant traffic lights

Backup control systems for traffic lights continued operation have witnessed consistent failure during peak periods especially in developing countries transportation systems mainly due to the electronic circuit technology in use. By leveraging on the concept of critical angle of reflectivity and propagation of light in an optical fibre, visible light to users of traffic lights was fed back into the control circuitry of a fault-tolerant traffic light to enable continuous operation in the event of unavailability of the main circuit. In this work, three orthogonal optical fibres corresponding to the red, amber and green signal lights help to sense available and visible light to users of traffic lights in real-time and sends the signal into a photoresistive sensors and circuits to determine when an abnormal condition or no-lighting of traffic light displays occurs. A comparator circuit interfaces with the photoresistive circuit and the Arduino Uno microprocessor to help trigger the available complementary control circuit to ensure continued operation. Safety considerations to mitigate abnormal operation of the resulting system included a comparator system that manages all variable situations occurring in the display of the traffic lights via programmed sequences of instructions embedded in the controller. The microcontroller circuit also included a starting condition in the amber lighting mode during switching on of the complementary circuit in a transition from main circuit to ensure that a near chaotic situation is avoided on change over for users/motorists of the system.