Why Do Traffic Lights Have Three Separate Lights Instead of One?
There are many concept designs for traffic lights on the internet. Nowadays, it is technically possible and cost-effective to put all colors in a single traffic signal light module. So why are three separate light modules still used for three different colors?
There are many concept designs for traffic lights on the internet. In these concept designs, there are interesting approaches for traffic lights, different colors are included in a single lamp or they promise to make traffic a little more fun by showing some animations.
Nowadays, it is technically possible and cost-effective to put all colors in a single traffic signal light module. So why are three separate light modules still used for three different colors?
Because, besides the color of light in traffic lights, the position of the light is also important for drivers. Colorblind drivers and pedestrians can understand which light is on thanks to the position of the light.
The red light is at the top of the vertical traffic lights and the far left at the horizontal traffic lights. Any light shining at this position means stop for colorblindness.
On the other hand, we all experience color blindness under certain conditions. It is known that the angle of view of the human eye is approximately 180 degrees. However, in only 90 degrees of this, color vision conditions occur. After 30 degrees from the fixation point of the eye, loss of color vision begins to be seen. People begin to lose their ability to distinguish colors from this point on. At 50 degrees and above it behaves like a true color blind.
Qualitative representation of visual details in a single glance of the eyes.
In the above image, it has been shown how colorful and sharp we see in the middle of the field of vision, and the color vision ability decreases in the surrounding areas. This represents a real example of vision from the human eye.
The human eye’s ability to perceive colors, shapes and texts.
The human eye’s ability to perceive movement at distant points is more than its ability to perceive colors. Movement of objects within the field of vision is seen more easily and in more detail. Instead of looking directly at the traffic light while traveling or waiting at traffic lights, we keep this lamp in our field of vision and watch the road and other vehicles. For this reason, we notice that the position of the light changes before the color of the light in traffic lights.
In a traffic light, if all the colors were contained in a module and the light color of this module changed according to the signaling condition, it might not be seen that the light turned from green to red. Therefore, the important thing in traffic lights is not only the color of the light, but also the position of the light. In this way, traffic lights can be noticed more easily and a safer environment can be created for drivers and pedestrians.
EN 12368, EN 50556 international standards clearly define the requirements for traffic signal lights and road traffic signs. Traffic lights and signaling applications to be used on all urban and intercity roads should also comply with these standards. Apart from this, worldwide practices should be taken as an example and local differences should be avoided.