The traffic light has many different names like a traffic signal, stop lights, etc. They are placed out there to control the traffic. The first traffic light appeared in the mid-1800's and consisted of two lamps, a red and a green one, like it is still commonly used nowadays in most countries. They are designed specifically for use as signalling devices and are generally positioned where the road intersects with other flows of traffic, whether it is motor vehicles or human traffic, such as pedestrian crossings, a crossroads or any other locations to control the flow of traffic.
LED Traffic light controllers are very common in built up areas and are a very effective way to control the flow of traffic at intersections. They give the traffic clear and simple instructions as to how to behave - who should proceed and who should stop. The only time you really need to show skill and judgement is when turning right at the traffic lights because unless there is a filter arrow showing, you have to give priority to oncoming vehicles. So in theory, junctions controlled by traffic lights should be the easiest type of intersection for learner drivers to deal with. However, many students have problems with traffic lights which cause them to fail their driving test.
The traffic control lights which are most commonly in use consist of a set of three lights, red, amber and green. They are generally set up in a vertical position with the red light at the top, amber light in the middle and the green light at the bottom. In some countries traffic lights may be set up horizontal.
When a vehicle approaches a set of traffic lights and the light on the signal is red, it is an indication to that vehicle to stop. The amber light indicates that the lights are about to change, either to red or to green depending on which part of the world you are in. When the lights change to green it is signalling that it is safe to proceed and the vehicle may continue its journey.
The variations in the use of traffic signal controller will vary depending on the country and any special needs for a particular intersection, for example special lights may employed for buses, pedestrians and bicycles etc; or special rules for controlling traffic which are turning in a particular direction. Some intersections can be quite complex and will make use of any combination of these.
The LEDs have truly brought a revolution to the traffic lighting industry. Whether it is signaling or countdown timers the LED proves to be the best.