Traffic control devices are those devices that are used for regulating the traffic on the roads and bring about a sense of awareness among pedestrians and vehicle users about road safety rules. Traffic signal controllers come in various shapes/patterns and can be placed anywhere on the roads so that they are easily visible for road users. They can be used to alert about dangers, to inform about route diversions, to announce directions, so on and so forth.

The normal function of traffic lights requires more than slight control and coordination to ensure that traffic moves as smoothly and safely as possible and that pedestrians are protected when they cross the roads. A variety of different control systems are used to accomplish this, ranging from simple clockwork mechanisms to sophisticated computerized control and coordination systems that self-adjust to minimize delay to people using the road.

The traffic light controllers uses input from detectors, which are sensors that inform the controller processor whether vehicles or other road users are present, to adjust signal timing and phasing within the limits set by the controller’s programming. It can give more time to an intersection approach that is experiencing heavy traffic, or shorten or even skip a phase that has little or no traffic waiting for a green light. Detectors can be grouped into three classes: in-pavement detectors, non-intrusive detectors, and detection for non-motorized road users. Some of the primary advantages of traffic control by using advanced traffic controllers are mentioned below:

• Increasing the traffic handling capacity of roads

• Reducing collisions and waiting time for both vehicles and pedestrians

• Encouraging travel within the speed limit to meet green lights

• Reducing unnecessary stopping and starting of traffic – this in turn reduces fuel consumption, air and noise pollution, and vehicle wear and tear

• Reducing travel time

• Reducing driver frustration and road rage