Traffic Light Signals

Traffic lights are used to control the flow of traffic. They are also known as traffic lamps, stop lights, stop and go lights and robots. 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 baliza v16 .

Most of the cities around the world have these installed to inform the road users by the use of lights in standard colours. The colour code is universal and has a precise sequence, and the colours used are red, amber and green. The precise sequence is very helpful for people who are colour blind.

The traffic 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 lights 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 first traffic lights were installed outside the Houses of Parliament in London, Great Britain in 1886 and at the time looked like railway signals with semaphore arms and red and green gas lamps.

The modern electric traffic lights was an American invention, and the first interconnected signal system was installed in Salt Lake City in 1917.

The length of time the amber light is illuminated can vary and in many places it is 5 seconds. In some places it may be as little as 3 seconds which considerably reduces the time the driver has to react. These times generally vary according to the set speed limit, and longer times are given for higher speed limits.

Lights are used in other types of road signs such as ' Slow Down' signs and fog warning signs which are illuminated when required, or in the case of a slow down sign they may be electronically activated as the speeding vehicle approaches.