At first glance, traffic light signals are all very simple and we have all known them since childhood. Red – stop, yellow – get ready, green – go. This is a very simple rule. In this article we will look at this rule deeper within the framework.
Let's find all the pitfalls hidden in traffic lights. The most interesting signals will be those that are located in the additional section of the traffic light and what signals there may be in this section. We will look at Chapter 6 of the Traffic Rules regarding the regulation of traffic through an intersection using traffic lights.
6.1. Traffic lights use green, yellow, red and white-lunar light signals.
Depending on the purpose, traffic light signals can be round, in the form of an arrow(s), a silhouette of a pedestrian or a bicycle, or X-shaped.
Traffic lights with round signals may have one or two additional sections with signals in the form of a green arrow(s), which are located at the level of the green round signal.
We will not consider white-lunar traffic lights, in the form of a silhouette of a pedestrian or a bicycle, and X-shaped ones in this article.
6.2. Round traffic lights have the following meanings:
- A green signal allows movement;
- A green flashing signal allows movement and informs that its time is expiring and a prohibitory signal will soon be turned on (digital displays can be used to inform drivers about the time in seconds remaining until the end of the green signal);
- The yellow signal prohibits movement, except in cases provided for in paragraph 6.14 of the Rules, and warns of an upcoming change of signals;
- A yellow flashing signal allows movement and informs about the presence of an unregulated intersection or pedestrian crossing, warns of danger;
- A red signal, including a flashing one, prohibits movement.
The combination of red and yellow signals prohibits movement and informs about the upcoming activation of the green signal.
This paragraph of the traffic rules describes round traffic lights. The most common traffic light, which is most often found on the roads.
6.3. Traffic light signals, made in the form of red, yellow and green arrows, have the same meaning as round signals of the corresponding color, but their effect extends only to the direction(s) indicated by the arrows. In this case, the arrow allowing a left turn also allows a U-turn, unless this is prohibited by the corresponding road sign.
The green arrow in the additional section has the same meaning. A switched off signal of an additional section means that movement in the direction regulated by this section is prohibited.
The first thing you should pay attention to is that the signals are made in the form of arrows, i.e. the arrow is a signal. The signal is not round. Traffic light signals with a contour arrow do not fit this definition, and clause 6.3 of the traffic rules is not applicable to them.
The second important point is that traffic light signals made in the form of arrows regulate only indicated directions. For example, if the red arrow to the right is on, then movement is prohibited only to the right; moving straight, turning left and turning around are not regulated by this signal.
The same applies to the green arrow signal, but only if the arrow is in the main section of the traffic light. Determining, for example, in the dark, whether this is the main section of a traffic light or an additional one is very simple - if the section is additional, then some signal in the main section of the traffic light must be on; if there are no other signals besides the arrow, then this means that the arrow is in the main sections.
6.4. If a black contour arrow(s) is applied to the main green traffic light signal, it informs drivers about the presence of an additional section of the traffic light and indicates other permitted directions of movement than the additional section signal.
This paragraph describes the purpose of the contour arrow of a traffic light signal. We see that a contour arrow can only be placed in the main section, and only on a green traffic light signal, and unlike a signal in the form of an arrow, a contour arrow allows movement only in the indicated directions. Traffic in other directions is prohibited.
We could finish our material here, if not for one very common situation in practice. We often come across a traffic light with the following signal:
In front of us is a traffic light with an additional section and a round signal. It would seem that according to paragraph 6.3, moving in the direction regulated by this section is prohibited.
But let's figure it out:
- According to clause 6.2, a round green signal allows movement in all directions, clause 6.3 regulates traffic light signals made in the form of arrows, in this case clause 6.3 is not applicable.
- The additional section may not be visible at night, and traffic signals may not have different meanings depending on the time of day.
- The direction regulated by the additional section is unknown to us, we only know that it is “different” from the signal in the main section, and in the main section we have a green signal that allows movement in all directions,
- The additional section may not contain a traffic light signal at all, but can be used, for example, for a timer.
Thus, with a given traffic light signal, according to clause 6.2, movement is allowed in all directions, unless otherwise prohibited by signs or markings.
Response from the Ministry of Internal Affairs Let's summarize:
- The round traffic light signal extends to all directions,
- The traffic light signal, made in the form of an arrow in the main section, applies only to the indicated direction and does not regulate traffic in other directions,
- The traffic light signal, made in the form of an arrow in the additional section, applies only to the indicated direction and prohibits movement in other directions,
- A round traffic light signal with a contour arrow on it applies only to the indicated direction and prohibits movement in other directions.
And this is how the TV show “Main Road” on NTV sees the situation.
Dear you without obstacles!
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, and proceed on a green.
There is no doubt that traffic lights should be installed in densely populated cities. Be that as it may, this is the only way to control traffic when there is no police officer nearby.
Driving every day from home to office, we cannot imagine a road without at least one traffic light, but there were times when traffic lights did not exist at all. Of course, the roads were relatively clear...
So, as already said, 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 lights are red, yellow and green? Why isn't it purple, brown and gray? There are several speculations 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 to this day, but it, in turn, had to borrow some things from other industries. A striking example is a traffic light.
The first traffic light was released in 1868 in London. It was used exclusively to control railroad traffic at the intersection of George and Bridge streets. The design was quite simple, but it performed its function very well. It was made of two vertical arrows that could move to a horizontal position when it was necessary to indicate to trains that they should stop. At a 45-degree angle, the system meant the same thing that a 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're 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 automobile industry.
A very important moment occurred in 1912 in the USA (where else?) thanks to Lester Farnsworth Wire, who was in charge of traffic for the Salt Lake City Police Department. The first manually controlled automobile traffic light had only two colors: red and green. Although there were practically no cars on the roads at that time and traffic rules had not yet been written down, 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 became a headache for the authorities. Similar lights, whether stars or street lamps, misled drivers, leading to fatal collisions.
Why are the traffic lights red, yellow and green?
Red is the color most often associated with blood and was thus chosen as a prohibitive 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, the reason for its use was also color symbolism. As with red, green is the source of human emotion. It is associated with something relaxing (like nature) that will not have a powerful negative impact on drivers. In addition, green is an easy color 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 recent years, especially in their effectiveness for colorblind people. Commissioners in many countries have addressed this issue in different ways, be it traffic lights with double red lights or sections of different shapes. One way or another, the classic design had to be changed a little.
Because color blindness is one of the most common forms of vision impairment, these days red is mixed in with a little orange to help colorblind people spot a brake light. For the same purpose, a shade of blue is added to green.
Why are the traffic lights red, yellow and green?
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The world's first traffic light appeared in London near the Houses of Parliament on December 10, 1868. It was intended for carts that had to stop to let pedestrians pass: an arrow raised up prohibited movement, and one located at an angle of 45° indicated that one should drive with caution. And at night, the traffic light was a gas lamp, which was rotated manually: the green light, as today, allowed passage, and the red light prohibited.
website I decided to figure out why the traffic light has 3 signals: red, yellow and green. It turns out that it has to do with our perception of light.
Red
The first thing that comes to mind when you think of the color red is danger. However, the main reason why red was chosen for the traffic ban is visibility from a greater distance. According to Rayleigh's law, discovered in 1871, the longer the wavelength, the less light is scattered. Of all the colors accessible to the human eye (not counting magenta), red has the maximum wavelength and is 620–740 nanometers.
Despite the fact that Rayleigh scattering was discovered later than the first traffic light, the choice of red for the prohibiting signal was based on experience gained on the railway, because the inventor of the world's first automatic traffic controller, John Peake Knight, was a railway engineer.
But the first traffic light did not last long: already on January 2, 1869, the gas in the lamp exploded, seriously injuring the policeman driving it. Because of this incident, traffic lights were banned in Britain and reappeared on the streets of London 60 years later.
Yellow
Patent for Garrett Morgan's invention.
According to the same Rayleigh law, yellow belongs to the “silver” in the competition for best visibility - its wavelength is 570–590 nanometers. The color orange is visible even better, which is why in modern traffic lights the yellow color often has an orange tint.
The first three-color traffic light was patented by Garrett Morgan in 1923, who then sold the patent to General Electric for $40,000. According to legend, he witnessed an accident on a street corner and decided that drivers did not have enough time to stop before when the red light came on, therefore, it was necessary to come up with a third, warning signal. So the traffic light turned yellow.
By the way, until the 90s of the last century, in some countries a yellow traffic light was used instead of a red one. The fact is that at night in a poorly lit area, the red light was difficult for drivers to see. However, after the invention of LED traffic lights, the color red was “reanimated” and yellow again began to be used only as a warning signal.
Green
The wavelength of green is 495–570 nanometers, which is shorter than that of red and green. Consequently, it is less visible than red and yellow, but better than other primary colors accessible to our perception.
It is interesting that the prototype of three-color automobile traffic lights also became railway traffic lights. However, the “trio” of colors was somewhat different. Red indicated a stop signal, green indicated readiness, and white allowed movement. But it was difficult for drivers to distinguish the white color from the light of lanterns or stars, which led to numerous accidents. Therefore, it was decided to abandon the white color and the railway traffic light became two-color: red prohibited movement, and green permitted.
By the way, some traffic lights in Japan use blue instead of green - and all because in the Japanese language for a long time the same hieroglyph was used to indicate both green and blue.
But why, why, why
Was the traffic light green?
And because, because, because,
That he was in love with life.©Zinoviev N.N.
A traffic light (from Russian light and Greek φορός - “carrying”) is an optical device that carries light information. We all know from childhood that traffic lights are red, yellow and green, and sometimes blue and lunar white. A red light prohibits movement, yellow is generally a warning signal that attracts attention, and green, blue and white signals permit movement. Why are these colors used in traffic lights around the world?
In 1868, English inventor John Peake Knight proposed using a device similar to a railway semaphore to regulate traffic in London near the British Parliament. During the day, the “stop” and “move with caution” signals were indicated by arrows that could take different positions, and in the evening, a rotating gas lamp was used for the same purposes, with the help of which red and green signals were given, respectively.
At the beginning of the 20th century, the first electric traffic lights began to be installed in America, first with two signals - red and green, and then a yellow signal was added to them. In the USSR, the first traffic light was installed in 1930, but instead of the usual green signal, a blue one was then used. In addition, until 1959, when the USSR acceded to the International Convention on Road Traffic and the Protocol on Road Signs and Signals, traffic light colors were in reverse order - the top was green and the bottom was red.
Of course, these colors of traffic lights were not chosen by chance. The choice was influenced by several factors, one of which is the psychology of human perception of different colors. Red color is traditionally considered a warning of danger, and green, on the contrary, is the color of life and calm.
But one of the main reasons for this choice of colors is the dependence of the degree of light scattering on its wavelength. According to Rayleigh's law, the degree of light scattering is inversely proportional to the fourth power of the wavelength. This means that short-wave radiation—blue and violet—is scattered more strongly. And red, as a color with a longer wavelength, will therefore be visible from a greater distance. Obviously, the most important thing is to warn about danger and prevent emergency situations, which is why the stop signal is indicated in red. For the same reason (degree of scattering), the blue signal, as having a shorter wavelength and scattering more strongly, gave way to green.
It's surprising that in Japan a green traffic light is called blue. The fact is that when the first street traffic lights appeared in Japan, the signals in them were red, yellow and blue. The blue lenses of traffic lights were eventually replaced with green ones, but the custom of calling the traffic-permitting signal “blue” remained. The peculiarity of the Japanese language is that, therefore, the Japanese call many green objects blue.
Why does the 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 generally accepted that this is due to two main reasons. One of them is in the field of physics phenomena, the other in the field of human psychophysiology.
Let's first turn to the history of the creation of the traffic light, and so:
Lester Wire from Salt Lake City (Utah, USA) is considered the inventor of the first electric traffic light. In 1912, he developed, but unfortunately did not patent, a traffic light with two round electric 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 Hogue at the intersection of 105th Street and Euclid Avenue. They had a red and green signal and made a beep when switching. The system was controlled by a police officer sitting in a glass booth 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 obstacles, and a left turn was made when the signal was green around the center of the intersection.
And only in 1918, to the two traffic light colors - red and green, another color was added - yellow. Three-color traffic lights using a yellow signal were installed in Detroit and New York.
James Hogue traffic light system (patent drawing)
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 Stephansplatz, and also 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 25 October and Volodarsky avenues, 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, who patented a traffic light of an original design in 1922, is often mentioned. 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 at the beginning of the 20th century.
Well, why did Lester Wire choose these colors? Perhaps, first of all, he was, of course, guided by the psychophysiological perception of color by a person - red as danger and prohibition, and green as calm and permission. But is this really so, let's turn again to the history and research of many of the inventors of the first traffic lights and their observations of the propagation of light of different spectrums in the air.
Let's consider all the factors by which these three colors were chosen - red, yellow and green!
PSYCHOPHYSIOLOGY.
As already mentioned, the first is psychophysiology - colors have different effects in their expressiveness.
In many publications on this topic, and even on the Internet, statements are published that the color red is often in nature for many living beings a signal of very close danger. This is very strange - because scientists have proven that most animals are color blind and do not distinguish colors. Well, further - as these “publications” claim, the possibility of running 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 pedestrian, indicating the presence of imminent danger! Perhaps, but let's explore this topic further.
It is further stated that these three colors 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 longest, so to speak, 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, and accordingly have the longest wavelength.
Next we will tell you what we brought up with this example, but for now we will continue to consider further explanations of what the publications write. It is further explained to us that the sensation of the color of the red and green signals, as prohibiting and prohibiting movement, must be clearly identified without the possibility of error. Which is what is observed. Even colorblind people who do not distinguish colors by shade of gray can accurately react to the color of a traffic light, red or green! Hm! Why then is it prohibited to have a driver’s license with such a disease!? - the question immediately arises! But the articles quickly rehabilitate themselves and explain this in such a way that - “... although this definition of a person’s physical defect of vision is greatly weakened. That’s why there is a ban on driving with such a disease...”
Well, the following explanation about the color green: “... it should be clearly understood that human vision reacts to light of different wavelengths with greater or less sensitivity. The choice of resolving green light is determined by the maximum proximity of this color to the level of the most clearly perceived part of the spectrum. It is visible, unlike other traffic light colors, from the greatest possible distance, because the eye is most sensitive 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 during daytime and twilight observation ... "
Here we will disagree a little and explain why we gave the example above with the visible color spectrum.
PHYSICS OF COLOR. DIFFUSION.
In fact, the colors green, yellow and red were chosen in traffic light design in part because red is perceived as danger, yellow as concentration, and green as permission. The question was the range of visibility under different weather conditions. And such a concept as light scattering was taken into account.
The concept of Rayleigh scattering was taken into account. What it is!? This 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 sky during the day. Rayleigh scattering is inversely proportional to the fourth power of wavelength, meaning that shorter wavelengths of blue light will be scattered more strongly than longer wavelengths (such as green and red). Which was taken into account. This dependence was derived by the British physicist John Rayleigh back in 1871. All the inventors of traffic lights based their choice on this dependence, because we know that 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 red, yellow and green colors scatter less than 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 one will dissipate a little faster, and the green one will be visible at a shorter distance than its two “big brothers”. I personally, as a person simply interested in everything, was very surprised by many publications on the Internet that I initially read while preparing this article, claiming that it is the green color that will be visible the furthest! But based on the physics of color and John Rayleigh's dependence, we see that everything 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 lights over a longer distance under various weather conditions - be it clear weather, fog or rain (of which England is rich), snow, hail and other weather phenomena, the light from the “traffic controller” of the traffic light should be visible as far as possible!
I think if blue, the color of calm, scattered the worst and was visible at a longer distance, then the choice would have fallen on this color, and not on red. And here the formula “danger of color” would not be suitable.
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