Traffic lights are a common thing these days, and you, like all other drivers, are required to follow the rules: stop at a red light, prepare for a yellow one, and pass on a green one.
There is no doubt that traffic lights should be in densely populated cities. Be that as it may, this is the only way to control traffic when there is no police nearby.
Riding every day from home to office, we can’t even imagine a road without at least one traffic light, but there were times when traffic lights didn’t exist at all. Of course, the roads were relatively free...
So, as already mentioned, when you get behind the wheel, you must adhere to certain rules. Traffic lights are the same all over the world and consist of three different colors that have their own specific purpose. But how did it happen that the traffic light is exactly red, yellow and green? Why isn't it purple, brown and grey? There are several suggestions on this topic, but first a little history.
It's no secret that the automotive industry pioneered many important things that are still used around the world today, but in turn, it had to borrow something from other industries. A good example is a traffic light.
The first traffic light saw the light in 1868 in London. It was used exclusively to manage rail traffic at the intersection of George and Bridge Streets. The design was quite simple, but performed its function very well. It was made up of two vertical switches that could change to a horizontal position to indicate to trains that they should stop. At a 45-degree angle, the system meant what yellow light does today: attention.
And now the most interesting thing: since the signaling device was completely invisible at night, the engineers decided to install primitive lights on it that would display the "stop" and "attention" modes. What was their color choice? Red for "stop" and green for "attention".
You are probably wondering how the green light became a signal for "attention"? Well, no one knows for sure, but that all changed a few years later when traffic lights made their way into the automotive industry.
A very important moment happened in 1912 in the USA (where else?) thanks to Lester Farnsworth Wire, in charge of traffic in the Salt Lake City Police Department. The first manually operated traffic light had only two colors: red and green. Although at that time there were practically no cars on the roads and the rules of the road had not yet been prescribed, the drivers were surprised by the new invention, so the presence of a policeman was necessary to force them to obey the device.
The first three-color traffic lights appeared again on the railway, but the trio was slightly different: red for "stop", green for "attention", white for "free". While the first two have a more or less obvious meaning, the white signal has become a headache for the authorities. Similar lights, whether they were stars or street lights, misled the drivers, leading to fatal collisions.
Why are traffic lights red, yellow and green
The color red is most often associated with blood and thus was chosen as a prohibitory signal. Symbolizing a dangerous situation leading to serious consequences, red has always been chosen as the color to encourage vehicles to stop and thus avoid accidents.
As for green, color symbolism also became the reason for its use. As with red, green is the source of human emotion. It is associated with something relaxing (such as nature) that will not have a powerful negative effect on drivers. In addition, the green color is easy to recognize at night.
The choice of yellow was surprising. Many believe that it symbolizes the sun, which is also considered a relaxing and at the same time attention-grabbing element.
Traffic lights have evolved over the years, especially in terms of their effectiveness for colorblind people. Commissioners in many countries have dealt with this issue in different ways, whether it was traffic lights with double red light or sections of different shapes. One way or another, the classic design had to be slightly changed.
Since color blindness is one of the most common forms of visual impairment, these days a little orange is mixed with red - in this case, color blind people are able to notice a brake light. For the same purpose, a shade of blue is added to green.
Why are traffic lights red, yellow and green
Today it is very difficult to imagine traffic rules without the main tool for streamlining traffic, which is a traffic light. It is designed to adjust and facilitate both vehicular and pedestrian traffic. There are different traffic light signals, depending on their functions. Although they are similar to each other, they have certain nuances that must be remembered.
Traffic light: definition
A traffic light is an optical signaling device that is designed to regulate the movement of cars, bicycles and other vehicles, as well as pedestrians. It is used in all world states without exception.
Interesting! Previously, there was no green light in traffic lights in Japan. It was replaced by blue. But scientists have proven that green is more acceptable to human eyes.
Types of traffic lights
The most common are three-color traffic lights with round signals: red, yellow and green. Traffic rules in some countries require the use of orange traffic lights instead of yellow ones. Signals can be placed both vertically and horizontally. If no other special traffic lights or additional sections are provided, then they regulate the movement of all types of transport, as well as pedestrians. Next, we will look at various types of traffic lights, from everyday to special ones.
Classic three-section traffic light
Such a traffic light has, as a rule, three colors, arranged in order: red, yellow, green - from top to bottom or from left to right. Such traffic lights are installed at intersections. They are designed for the simultaneous passage of all types of transport in all directions permitted by traffic rules. They are also installed at regulated pedestrian crossings located between intersections. It is allowed to install such a traffic light at a railway crossing in settlements, at the intersection of a road with tram tracks, in front of a bicycle path and a carriageway. They can also be seen where the roadway narrows to allow oncoming traffic to pass alternately.
Interesting fact!The first three-section traffic light was installed in Detroit in 1920.
two-section
Traffic lights with two sections are used to regulate the flow of traffic in the territories of industrial enterprises and organizations, as well as during the narrowing of the roadway to organize a single-lane reverse traffic flow.
Single section traffic light with yellow light
Such a one-color traffic light is found at unregulated intersections and pedestrian crossings.
Traffic lights with additional section
Traffic lights can also be equipped with additional sectional sections with arrows or arrow contours. They regulate the movement of traffic in one direction or another. Such traffic lights work, according to the traffic rules, as follows: the contours of the arrows on all signals of a conventional three-color traffic light mean that its action extends only in one specified direction.
An additional section of a traffic light with a green arrow on a black background allows traffic according to the traffic rules, but does not provide advantages during the siding. Sometimes you can find an always burning green signal, which is made in the form of a plate with a solid green arrow. This means according to the traffic rules that the turn is allowed, despite the prohibitory traffic lights.
Such traffic lights are installed in those places where it is necessary to organize conflict-free traffic at intersections. If one of these traffic lights turns green, then when crossing the intersection, you can not give way. To avoid emergencies, personal traffic lights are placed above each lane, which show the direction of movement that is allowed from a particular lane.
Reversible traffic lights
Reversing traffic lights are used to regulate traffic along the lanes of the carriageway. These are dedicated band control knobs. At such traffic lights, from two to three signals can be placed: a red signal in the form of the letter "X" prohibits movement in a particular lane. The green arrow, which is directed down, on the contrary, allows movement. The yellow diagonal arrow indicates that the lane mode has been changed and indicates in which direction you need to leave it.
Traffic lights to control traffic across a pedestrian crossing
Typically, such traffic lights have only two types of signals: The first one allows, the second one forbids. As a rule, they correspond to green and red colors. The signals themselves can be of different shapes. Often they are depicted as a stylized silhouette of a person: standing red and walking green. For example, in America, the prohibition signal is made in the form of a red raised palm, meaning "stop." Sometimes inscriptions are used: red “stop” and green “walk”. In other countries, respectively, in other languages.
Traffic lights with automatic switching are installed on highways with busy traffic. But there are times when you can switch the traffic light by pressing a special button, which allows you to cross the road for a certain time. Modern traffic lights for convenience are equipped with a digital countdown display. For blind people, sound devices are mounted in traffic lights.
To regulate the movement of trams
A traffic light for a tram, as a rule, is placed in front of areas with limited visibility, long ascents and descents, at a tram depot and in front of arrows. There are two types of traffic lights for the tram: green and red. They are installed either to the right of the tracks, or hung in the center above the contact wire. Basically, such traffic lights notify tram drivers about whether the path is busy further or not. They do not regulate the movement of other vehicles and are purely individual. Their work is built automatically.
Traffic signals: traffic rules
Round lights mean the following: a static green signal allows the movement of vehicles or pedestrians, and a flashing green traffic light means that a prohibition signal will light up soon, but traffic is still allowed.
Interesting fact!In general, residents of large cities spend about six months of their lives waiting for a traffic signal to pass.
What does a yellow traffic light mean? It warns that the prohibiting signal will be replaced by an enabling one or vice versa, and for the duration of its action prohibits movement. A flashing yellow traffic light means that the section of the road on which this traffic light is located is not regulated. If it is located at an intersection and operates in this mode, then the intersection is unregulated. Drivers are guided by those articles of the traffic rules, which stipulate the passage of unregulated intersections. A static and flashing red signal prohibits movement in any direction.
Red and yellow traffic lights burning at the same time indicate that it is forbidden to move further, and the green light will soon turn on. The white-moon signal of the traffic light informs that the alarm is working, and you can continue driving. Such traffic lights are installed on tram and railway tracks.
Traffic lights that look like arrows mean the following: red, yellow and green arrows mean the same as round signals, only they act in a certain direction. An arrow that points to the left also allows a U-turn, unless this is prohibited by the corresponding traffic sign next in priority.
The green arrow of the additional section has a similar meaning. If this signal is turned off, or the red outline is on, then movement in this direction is prohibited. If the main green signal has a black outline arrow, then this means that there are other directions of movement than those indicated by the additional section.
What is more important: a sign, a traffic light or a marking?
The rules of the road imply the following priority: the main one is the traffic controller, then the traffic light, then the sign and then the markings. The signals of the traffic controller have priority over traffic signals and traffic signs. They are mandatory. All traffic signals, except for flashing yellow, are more significant than road signs. All road users are obliged to follow the instructions of the traffic controller, even if they contradict traffic lights, signs and markings.
The capital of Germany has a traffic light with thirteen signals. It is not so easy to understand his testimony right away.
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Why does a traffic light have these three colors - red, yellow and green!?
Why did the choice of colors for traffic lights fall on red, yellow and green? It is believed that this is due to two main reasons. One of them is in the field of phenomena of physics, the other in the field of human psychophysiology.
Let's first turn to the history of the creation of a traffic light, and so:
The inventor of the first electric traffic light is Lester Wire from Salt Lake City (Utah, USA). In 1912, he developed, but unfortunately did not patent his own, a traffic light with two round electrical signals, red and green.
On August 5, 1914, in Cleveland, Ohio, USA, the American Traffic Signal Company installed four electric traffic lights designed by James Hoag at the intersection of 105th Street and Euclid Avenue. They had a red and green signal and, when switched, emitted a sound signal. The system was controlled by a policeman sitting in a glass box at an intersection. Traffic lights set traffic rules similar to those adopted in modern America: a right turn was carried out at any time in the absence of interference, and a left turn was carried out on a green signal around the center of the intersection.
And only in 1918, to the two colors of the traffic light - red and green, another color was added - yellow. Tri-color traffic lights using a yellow signal have been installed in Detroit and New York.
James Hoag's traffic light system (drawing from patent)
In Europe, similar traffic lights were first installed in 1922 in Paris at the intersection of Rue de Rivoli and Sevastopol Boulevard. Back in Hamburg on the Stephansplatz square, as well as in England - in 1927 in the city of Wolverhampton.
In the USSR, the first traffic light was installed on January 15, 1930 in Leningrad at the intersection of avenues on October 25 and Volodarsky, now Nevsky and Liteiny avenues. And the first traffic light in Moscow appeared on December 30 of the same year at the corner of Petrovka and Kuznetsky Most streets.
In connection with the history of the traffic light, the name of the American inventor Garrett Morgan is often mentioned, who patented an original traffic light in 1922. There is a persistent myth about Morgan's great influence on the development of traffic lights, but in reality he is only one of many inventors of various traffic lights of the early 20th century.
Well, that's why Lester Vayre chose these colors, perhaps, first of all, he was guided, of course, by the psycho-physiological perception of color by a person - red as a danger and prohibition, and green as calmness and resolution. But is this really so, let's turn again to the history and research of many inventors of the first traffic lights and their observations of the propagation of light, of different spectra, in the air.
Let's consider all the factors on which these three colors were chosen - red, yellow and green!
PSYCHOPHYSIOLOGY.
As already mentioned, the first is psychophysiology - colors affect differently in their expressiveness.
In many publications on this topic, and even on the Internet, statements are published that the red color is often in nature for many living beings a signal of a very close danger. This is very strange - because scientists have proven that most animals are color blind and do not distinguish colors. Well, further - according to these "publications" that the opportunity to run over a pedestrian is a dangerous situation for two participants on the road and the red signal excites the nerve centers of the driver and the pedestrian, indicating the presence of an imminent danger! Perhaps, but still, let's explore this topic further.
It is further stated that it is these three colors that are most well perceived by the human eye in terms of their physical parameters and the wavelength inherent in them. Yes, this is exactly so, because these three colors have the largest, if I may say so, wavelength. Here's a look at the visible spectrum of colors.
From the above figure, we see that our - red, yellow and green colors are at the very beginning of the visible spectrum, respectively, have the longest wavelength.
Next, we will tell you what we brought this example to, but for now we will continue to consider further explanations of what the publications write. Further, it is explained to us that the color perception of red and green signals, as forbidding and forbidding movement, must be clearly identified without the possibility of error. What is observed. Even color-blind people who do not understand colors by the tone of gray can accurately react to the color of a traffic light red or green! Hm! Why, then, is it forbidden to have a driver's license with such a disease!? - the question immediately arises! But the articles are quickly rehabilitated and explain it in such a way that - “... although this definition of a person’s physical defect of vision is greatly weakened. Therefore, there is a ban on driving with such a disease ... ".
Well, the following explanation about the green color: “... it should be clearly understood that a person’s vision of light of different wavelengths of light reacts with greater or lesser sensitivity. The choice of resolving green light is due to the maximum approximation of this color to the level of the most clearly perceived part of the spectrum. It is visible in contrast to other traffic light colors from the greatest possible distance, because the highest sensitivity of the eye is at 555 nm. And the perception of green color, which has a range of values of 500-550 nm of the spectrum, at different times of the day does not fall below 0.5 of the maximum sensitivity value, both in daytime and twilight observation ... "
Here we disagree a little and explain why we gave the above example with the visible color spectrum.
PHYSICS OF COLOR. DIFFUSION.
In fact, the colors green, yellow and red were chosen in the design of the traffic light in part because red is perceived as danger, yellow as focus, and green as permission. The question was in the range of visibility under different weather conditions. And such a concept as light scattering was taken into account.
Such a concept as Rayleigh scattering was taken into account. What it is!? It is the elastic scattering of light or other electromagnetic radiation by objects or surfaces much smaller than the wavelength of the incident light. This can often occur on clear solids and liquids, but is more common in gases. This type of scattering occurs in the blue of the sky during the day. Rayleigh scattering is inversely proportional to the fourth power of the wavelength, meaning that shorter wavelength blue light will be scattered more strongly than longer wavelengths (such as green and red). which was taken into account. This dependence was deduced by the British physicist John Rayleigh back in 1871. All the inventors of traffic lights based their choice on this dependence, because we know the air both day and night contains drops of suspended liquid. For this reason, Rayleigh scattering was taken into account.
Those. everything is much simpler than the perception of colors. It's all about the physics of color. From the figure, we can see that the red, yellow, and green colors scatter less than the other colors. From this we can conclude that in bad weather - fog or rain, the red color of the traffic light will be visible the farthest, the yellow will dissipate a little faster, and the green will be visible at a lesser distance than its two "older brothers". Personally, as a person who is simply interested in everything, I was very surprised by the many publications on the Internet that I initially read when preparing this article, stating that it is the green color that will be seen the farthest! But based on the physics of color and John Rayleigh's dependency, we see that it will be quite the opposite!
So the reason for choosing these three traffic light colors turns out to be much more mundane than others imagine - namely, in the properties of different colors and their dispersion in the air! People were worried about road safety and the visibility of traffic signals over a longer distance under various weather conditions - whether it be clear weather, fog or rain (which England is rich in), snow, hail and other weather phenomena, the light from the "traffic controller" of the traffic light should be seen as far as possible!
I think if the blue color - the color of calmness, dissipated the worst of all and was visible at a longer distance, then the choice would have fallen on this color, and not on red. And here the formula of "color danger" would not fit.
Traffic lights are a common thing these days, and you, like all other drivers, are required to follow the rules: stop at a red light, get ready for a yellow one, and pass on a green one. There is no doubt that traffic lights should be in densely populated cities. Be that as it may, this is the only way to control traffic when there is no police nearby...
Riding every day from home to office, we can’t even imagine a road without at least one traffic light, but there were times when traffic lights didn’t exist at all. Of course, the roads were relatively free... So, as already mentioned, when you get behind the wheel, you must adhere to certain rules. Traffic lights are the same all over the world and consist of three different colors that have their own specific purpose.
But how did it happen that the traffic light is exactly red, yellow and green? Why isn't it purple, brown and grey? There are several assumptions on this subject, but first a little history. It's no secret that the automotive industry pioneered many important things that are still used around the world today, but in turn, it had to borrow something from other industries.
A good example is a traffic light. The first traffic light saw the light in 1868 in London. It was used exclusively to control rail traffic at the intersection of George and Bridge streets. The design was quite simple, but performed its function very well. It was made of two vertical arrows that could change to a horizontal position when it was necessary to show the trains that they should stop. At a 45-degree angle, the system meant what yellow light does today: attention.
And now the most interesting thing: since the signaling device was completely invisible at night, the engineers decided to install primitive lights on it that would display the "stop" and "attention" modes. What was their color choice? Red for "stop" and green for "attention". You are probably wondering how the green light became a signal for "attention"? Well, no one knows for sure, but that all changed a few years later when traffic lights migrated to the automotive industry.
A very important moment occurred in 1912 in the United States thanks to Lester Farnsworth Wyer, who was in charge of traffic in the Salt Lake City Police Department. The first manually operated traffic light had only two colors: red and green. Although at that time there were practically no cars on the roads and the rules of the road had not yet been prescribed, the drivers were surprised by the new invention, so the presence of a policeman was necessary to force them to obey the device.
The first three-color traffic lights appeared again on the railway, but the trio was slightly different: red for "stop", green for "attention", white for "free". While the first two have a more or less obvious meaning, the white signal has become a headache for the authorities. Similar lights, whether they were stars or street lamps, misled the drivers, which led to fatal collisions.
The color red is most often associated with blood and thus was chosen as a prohibitory signal. Symbolizing a dangerous situation leading to serious consequences, red has always been chosen as the color to encourage vehicles to stop and thereby avoid accidents. As for green, color symbolism also became the reason for its use.
As with red, green is the source of human emotion. It is associated with something relaxing (such as nature) that will not have a powerful negative effect on drivers. In addition, the green color is easy to recognize at night. The choice of yellow was surprising. Many believe that it symbolizes the sun, which is also considered a relaxing and at the same time attention-grabbing element.
Traffic lights have evolved over the years, especially in terms of their effectiveness for colorblind people. Commissioners in many countries have dealt with this issue in different ways, whether it was traffic lights with double red light or sections of different shapes. One way or another, the classic design had to be slightly changed. Since color blindness is one of the most common forms of visual impairment, these days a little orange is mixed with red - in this case, color blind people are able to notice a brake light. For the same purpose, a shade of blue is added to green.
It is difficult to find a modern person who has never seen a traffic light. The device, which glows red, yellow or green at certain intervals, regulates the movement of cars and pedestrians. Everyone knows the meaning of the signals from childhood, but not everyone knows why these colors were chosen for the traffic light.
In 1868, the world's first traffic light appeared on one of London's streets near Parliament. The device was designed to help police unload the busy Bridge Street. The idea for such a device came to the mind of engineer John Peak Knight. Although, if objective, he simply copied it from the railway semaphore.
The cab and stagecoach drivers saw a 6.7-meter-high pole with movable arrows. They deviated to the sides (“stop” signal) or down by 45 degrees (“attention” signal, allowing you to drive). At night, a gas lamp with red and green lenses was used. To make the system work, a police constable was on duty at the traffic light around the clock.
So, the red and green colors were borrowed from the railway semaphore. It is curious that at first the “attention” signal was given in green, and permission to move followed the white signal.
But this arrangement failed. Machinists sometimes mistook large stars in the sky for signs, which led to disasters.
Only a decade later, physicists were able to explain why red, green and yellow became a kind of standard for traffic lights. And of the whole rainbow, it is these colors that have the longest wavelength of the spectrum. Therefore, these signals are visible from as far away as possible.
