How the traffic light came about and why they chose yellow, green and red colors for it. Traffic light: colors in order, description and meaning

Today it is very difficult to imagine traffic rules without the main tool for regulating traffic, which is a traffic light. It is designed to regulate and facilitate both vehicular and pedestrian traffic. Distinguish different signals traffic lights, depending on their functions. Although they are similar to each other, they have certain nuances that need to 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 countries without exception.

Interesting! Previously, there were no green lights 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 regulations in some countries require the use of orange traffic lights instead of yellow ones. Signals can be located both vertically and horizontally. If other special traffic lights or additional sections are not provided, then they regulate the movement of all types of transport, as well as pedestrians. Next we will look at different kinds traffic lights, from everyday ones to special ones.

Classic three-section traffic light

Such a traffic light, as a rule, has 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 to allow simultaneous passage of all types of transport in all directions permitted by traffic regulations. They are also installed at controlled pedestrian crossings located between intersections. It is allowed to install such a traffic light at a railway crossing in populated areas, at the intersection of the road with tram tracks, in front of bike path and the roadway. They can also be seen where the roadway is narrowed to allow oncoming traffic to pass alternately.

Interesting fact!The first three-section traffic light was installed in Detroit in 1920.

Two-piece

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

This 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 outlines. They regulate the movement of traffic in one direction or another. According to traffic regulations, such traffic lights operate 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 indicated direction.

Additional traffic light section with green arrow on a black background, the traffic rules allow travel, but do not provide advantages during passing. Sometimes you can find an always-on green signal, which is made in the form of a sign with a solid green arrow. This means, according to traffic rules, that turning is allowed, despite the prohibitory traffic lights.

Such traffic lights are installed in 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 don’t have to give way. To avoid emergency situations, personal traffic lights are placed above each lane, which show the direction of movement that is allowed from a particular lane.

Reversible traffic lights

To regulate traffic along the roadway lanes, reversible traffic lights are used. These are special band control regulators. Such traffic lights can have from two to three signals: A red signal in the form of the letter “X” prohibits movement in a specific lane. A green arrow pointing down, on the contrary, allows movement. A yellow diagonal arrow signals that the lane mode has changed and shows in which direction you need to leave it.

Traffic lights for regulating traffic through a pedestrian crossing

Typically, such traffic lights have only two types of signals: the first one allows, the second one prohibits. As a rule, they correspond to green and red colors. The signals themselves can be of different shapes. They are often depicted as a stylized silhouette of a person: standing in red and walking in green. For example, in America, the prohibition signal is made in the form of a red raised palm, meaning “stop”. Sometimes the following inscriptions are used: red “stop” and green “walk”. In other countries, respectively, in other languages.

On highways with heavy traffic, traffic lights with automatic switching are installed. But there are times when you can switch the traffic light by pressing special button, which allows you to cross the road within a certain time. Modern traffic lights are equipped with a digital countdown display for convenience. For blind people, sound devices are installed in traffic lights.

To regulate the movement of trams

A traffic light for a tram is usually placed in front of areas with limited visibility, long ascents and descents, at a tram depot and in front of switches. There are two types of traffic lights for trams: green and red. They are installed either to the right of the tracks or hung centrally above the contact wire. Basically, such traffic lights notify tram drivers whether the path further is busy or not. They do not regulate the movement of other vehicles and are purely individual. Their work is built automatically.

Traffic lights: driving rules

Round light signals mean the following: a static green signal allows the movement of vehicles or pedestrians, and a flashing green traffic light means that a prohibitory signal will soon come on, but for now movement is allowed.

Interesting fact!Residents of large cities generally spend about six months of their lives waiting for a traffic light.

What does a yellow traffic light mean? It warns that the prohibiting signal will be replaced by a permissive one or vice versa, and for the duration of its action it prohibits movement. A flashing yellow traffic light means that the section of the road on which the 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 that stipulate the passage of unregulated intersections. A static and flashing red signal prohibits movement in any direction.

The red and yellow traffic lights that are on at the same time indicate that it is prohibited to move further, and the green light will soon turn on. The white-lunar traffic light signal informs that the alarm system 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 thing as round signals, only they act in a certain direction. An arrow pointing to the left also allows a U-turn, unless the corresponding next priority traffic sign prohibits it.

The green arrow of the additional section has a similar meaning. If this signal is turned off or the red outline is on, it means that 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?

Rules traffic imply the following priority: the main one is the traffic controller, then the traffic light, then the sign and then the markings. Traffic controller signals take precedence over traffic light signals and road sign requirements. They are mandatory. All traffic lights, except flashing yellow, are more significant than road signs. All road users are required to follow the instructions of the traffic controller, even if they contradict traffic lights, signs and markings.

In the capital of Germany there is a traffic light with thirteen signals. It is not so easy to understand his testimony right away.

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Today, every person understands what a traffic light is. The colors: red, yellow and green are familiar even to a child.

However, there was a time when these optical devices did not exist, and crossing the street was not very easy. Especially in big cities, passers-by had to pass endless horse-drawn carriages for a long time.

On the cross streets there was confusion and endless disputes.

A short excursion into history

The traffic light was originally invented by the British. It was staged in London at the end of 68 of the 19th century. It was controlled by a man. The mechanism had two hands. When they were in horizontal position, movement was prohibited, and when they were omitted, passage was allowed. At night they turned on a gas burner, which gave a red and green signal. It turned out to be unsafe. The gas exploded, injured a policeman, and the traffic light was removed.

It was only at the beginning of the twentieth century that an automatic traffic light was patented in America. Colors were not used in it; inscriptions replaced them.

The red color is very visible in any weather: when the sun is shining brightly, it is raining, or there is fog. From a physical point of view, the color red is maximum length waves. This is probably why it was chosen as forbidden. The meaning of red is the same all over the world.

The other signal at the traffic light is green. This is the color of calm and tranquility. It has a relaxing effect on human brain. A green traffic light allows movement. It can be seen far enough away; any driver sees this color long before passing the traffic light and calmly crosses the intersection without braking.

However, as they say, there is an unspoken rule according to which it is still worth slowing down when driving through a dangerous intersection, even when the traffic light shows green. This action often helps avoid serious accidents.

Yellow - pay attention

Yellow traffic light color is intermediate. It carries a warning function and calls on traffic participants to pay attention. The color yellow is said to symbolize intelligence, intuition and intelligence. It usually lights up after red, calling on drivers to get ready to move. As practice shows, many drivers perceive a yellow traffic light as permission and start moving. This is wrong, although it is not punishable by penalties. When the yellow light comes on, you need to depress the clutch and get ready, but to start driving it is better to wait for the green light, especially since the wait is only a couple of seconds.

In reverse order: green, yellow, red - the traffic light does not work. IN modern devices after green, red immediately lights up, while in the last minutes green begins to blink.

You can also sometimes see a continuously flashing yellow light. This indicates that the traffic light is disabled or broken. Flash most often yellow traffic lights at night.

Pedestrian traffic light

There is also a traffic light to regulate pedestrian traffic. What colors does it use? Red and green - definitely, but yellow is absent as unnecessary. A person does not need any special preparation to cross the road.

They are usually depicted as walking men. For the convenience of pedestrians Lately a time counter is used. A special stopwatch counts down how many seconds are left before the opposite signal turns on.

As with regular traffic lights, red prohibits traffic, and green indicates that the passage is open.

When driving through an intersection, drivers should be aware that pedestrians have the right of way. So, for example, at an intersection a car turns right at a green traffic light, while pedestrians crossing a perpendicular road also see a green light. In this case, the motorist is obliged to let all pedestrians pass and only then continue driving.

What is a "green wave"

In large cities, traffic on highways is accompanied by a large number of traffic lights that regulate traffic. A traffic light, the colors of which are known to everyone, switches them at certain intervals. This frequency is adjusted automatically and ensures the safety of vehicle movement.

The “green wave” is tied to the speed of the car. It is assumed that, moving with a certain average speed, the driver, when he hits a green traffic light, will also hit green along the entire length of the highway. The three traffic light colors switch at regular intervals, and there is consistency between a number of traffic lights. At all intersections of the route, coordinated according to this principle, there is the same cyclicity.

The “Green Wave” was developed for the convenience of passing intersections; technically, this is not particularly difficult to implement. As a rule, on such highways additional signs are installed with the recommended speed, which will ensure non-stop passage of intersections.

The three-eyed traffic light is an assistant to the driver and pedestrian. The colors switch in order and adjust the progress, ensuring the safety of all road users. By following them conscientiously, you can avoid serious accidents and unpleasant situations on the roads.

The order of alternating traffic lights complies with the international Convention on road signs and signals. Traffic light signals alternate in the following sequence: red - red with yellow - green - yellow - red. Alternation of signals red - green - yellow - red or red - yellow - green - yellow is allowed.

A red, non-flashing signal prohibits movement along the entire width of the roadway. Types of red signal:

Contour black arrow on a red background round shape prohibits movement in the direction of the arrow;

An oblique red cross prohibits movement in the lane above which it is installed;

A red silhouette of a person prohibits pedestrian movement;

Flashing red prohibits entry to a railway crossing, bridge, pier, etc.

A yellow non-flashing signal obliges all drivers to stop in front of the stop line, with the exception of those who could not stop before the intersection.

Yellow connected to red warns that the green signal is turned on.

A yellow flashing signal warns of the presence of an intersection and does not prohibit movement.

A green, non-blinking signal, in the absence of any additional traffic light sections, allows traffic along the entire width of the roadway in all directions.

Types of green signal:

A black arrow on a green background of a square, round shape, as well as a green arrow on a black background of a round shape - permission to move in the direction of the arrow;

Green arrow on a black background, square in shape, directed downwards, allows movement along the lane above which it is installed;

A signal in the form of a green silhouette of a person allows the pedestrian to move;

The green arrow of the additional traffic light section allows movement in the direction of the arrow, regardless of the signal of the main traffic light;

A flashing green signal indicates the end of the enable signal.

Traffic permission common use depends on the combination of the included signals of the upper and lower rows of a special traffic light. Turning on the lower signals, movement is prohibited in all directions.

Research has shown that there is a so-called critical section in front of the intersection and, being within this section, the driver cannot stop in time in front of the stop line when the permitting signal changes to a prohibiting one.

The critical section is determined by the distance from the stop lines to the point from which 10% of drivers cannot stop. The length of the critical section depends on the speed of movement. So, at a speed of 50 km/h, the length of this section is 43 m and the travel time for this section requires 3.1 s; at a speed of 60 km - the length of the section is 58 m and the travel time is 3.5 s; at a speed of 80 km, the length of the section is 91 m and the travel time is 4.1 s.

Hence the travel time of the critical section at various speeds movement fluctuates within 3-4 s. This prompted the use of a flashing green signal as a warning signal and the flashing time to be taken equal to the time it took to travel through the critical section. In order not to reduce throughput intersection. with a permitting signal, a green flashing signal is introduced partially due to the duration of the yellow one, which will allow you to safely pass the intersection.

Types of traffic lights. Traffic lights are classified according to their functional purpose-transport and pedestrian; by design - one, two-section, three-section and three-section with additional sections; according to the role performed in the process of motion control - main, backup and repeaters.

There are two main groups of traffic lights: transport and pedestrian, which in turn are divided into types. There are 8 types of traffic lights and 2 types of pedestrian ones. The first number of the traffic light indicates the group, the second digit indicates the type of traffic light.

Transport traffic lights Type 1 have three round signals with a diameter of 200 or 300 mm, located vertically or horizontally.

The first type is used with additional sections, in which arrows indicate the direction of movement (arrows on a black background). Traffic lights of this type are used to regulate all directions of traffic at intersections. Their use is allowed at railway crossings, intersections with tram and trolleybus lines, at narrowings of the roadway, etc.

Traffic lights of 2 types. The lenses of the traffic lights are marked with the outlines of arrows. indicating permitted or prohibited movement. In this case, the green signal (arrow) is printed on a black background. Type 2 traffic lights are used to regulate traffic in certain directions (arrows indicated on the lens).

Traffic lights type 3. They are used as repeaters and in conjunction with traffic lights of type 1.

They are installed under the main traffic light at a height of 1.5-2 m from the roadway. The diameter of the signals is 100 mm. If the main one has an additional section, then the repeater is equipped with an additional section. This type of traffic light can be installed to control bicycle traffic.

Traffic lights type 4. Used to control entrances to individual lanes during reverse traffic.

They are installed above each strip at its beginning. They have horizontal signals; on the left - in the form of an oblique red cross, on the right - in the form of a green arrow pointing downwards. Both signals are performed on a black rectangular background. dimensions 450 x 500 mm.

These traffic lights can be used in conjunction with type 1 traffic lights if reversible traffic is not organized across the entire width of the roadway. In this case, the operation of a type 1 traffic light does not apply to reversible lanes. This lane may be limited by a double broken line 1.9 when the type 4 traffic light is switched off.

Traffic light type 5. Has 4 pale moon-colored round signals with a diameter of 100 mm. This traffic light is used in cases of conflict-free regulation of the movement of trams, route buses, and trolleybuses moving along a specially designated lane. The traffic management scheme at the intersection ensures conflict-free passage of the specified types along with the general flow, so there is no need to use this type at the intersection.

Traffic light type 6. It has two (or one) red round signals with a diameter of 200 or 300 mm, located horizontally and operating in alternating flashing mode. When the signals are turned off, movement is permitted. They are installed in front of railway crossings, drawbridges, piers, ferry crossings, and in places where special vehicles enter the road.

Traffic light type 7. It has one yellow signal, constantly flashing. It is used at unregulated intersections of increased danger.

Traffic lights type 8. They have two vertical signals of red and green colors of a round shape, W 200 or W 300 mm. They are used when the roadway is temporarily narrowed, when alternating traffic is organized along one lane. Also used to control low-intensity traffic in the internal areas of garages, enterprises and organizations where speed limits have been introduced.

Pedestrians have two vertically located signals of a round or square shape with a circle diameter or square side of 200 mm or 300 mm. All pedestrian crossings at an intersection controlled by traffic lights are equipped.

Large traffic lights are installed on main streets, squares, and on roads with traffic speeds of T.S. 60 km/h.

Construction of traffic lights. The traffic light consists of separate sections (Fig. 1) and each section is intended for a specific signal. Depending on the type of traffic light, the sections have different shape, your symbols, light sources, etc. Common to all sections is the presence of an optical device housed in a separate housing.

Figure 15 - Traffic light design

The sections are connected to each other by threaded hollow bushings 1, and supply wires are passed through them. The section consists of a body 8, a sun visor 4 and a cover 6. They are made of sheet steel or plastic. An optical device is mounted in the lid, which consists of a reflector 7, a colored diverging lens 3 and a movable glass 10 with an electric lamp. When moving the glass, the lamp filament is installed at the focus of the reflector. To connect the current supply, there is a block 9 at the bottom of the section.

Light source.

Incandescent lamps for both general and special purposes are used as a light source. Thus, gas-light tubes or emitting diodes are used as a light source. The main disadvantage of an incandescent lamp for general use is the large length of the filament, which is difficult to focus, low vibration resistance of the lamps, and also have a short service life (500-800 hours):

It has been proven that filament burnout occurs mainly due to inhomogeneity in wire diameter, spiral pitch, electrical resistance and evaporation rate.

Some traffic light designs use halogen lamps. Despite their small size, they have an increased specific light output and a compact filament, and these lamps focus well. However, these lamps are not widely used due to their high cost.

Two simultaneously operating lamps can be used in one section, but this requires the installation of a special reflector and a bifocal lens. This solution is associated with a more complex design and higher cost.

Abroad, a curved gas-light tube has been used as a light source. The tubes contain filler in red, yellow or green colors, which allows you to do without a colored lens. To glow the tubes, a voltage of over 2000 V is required, so a transformer is required. They have a long service life, but in terms of signal luminous intensity they are 5-6 times inferior to modern traffic lights with incandescent lamps.

Traffic light lenses.

IN last years Plastic lenses have become widespread here and abroad. They have advantages over glass in ease of manufacture, higher strength when exposed to shock and vibration loads, and also lighter weight (about 3 times). The material of such lenses is usually polycarbonate.

Diffusing lenses are designed to redistribute" luminous flux in ■ space. To do this, a patterned, rhombic, prismatic or teardrop-shaped pattern is formed on their inner side. Important characteristic lens is the light scattering angle - the largest angle within which the light intensity is reduced by half compared to its axial value. For modern lenses, this angle is within 5-15°, which ensures normal signal visibility on multi-lane roads (100 m).

Reflector.

The reflector is characterized by two main internal surfaces: paraboloid, which provides concentration of the light flux, and conical (or cylindrical), designed to increase the depth of the reflector and thereby reduce the burnout of the lens dye.

With a short focal length, there is a danger of a false traffic light signal (phantom effect), when a beam from an extraneous light source hits the reflector and returns to the observer.

In the designs of modern reflectors, the focal plane AA is brought as close as possible to the plane of the light hole, behind which the non-working conical surface begins.

As a rule, the following condition is met:

(13)

where: - diameter of the light hole of the reflector, mm.

Reflectors are made of steel, aluminum alloys or plastics with subsequent processing of the internal surface. Great Application plastic reflectors with a working surface obtained by vacuum spraying are obtained.

Anti-phantom devices.

The anti-phantom device in a traffic light is a sun visor, but when the sun is in a low position (for example, east-west, west-east), all traffic lights may turn on.

There are several methods for eliminating the phantom effect, but they require changes in the design of the reflector or lens of the traffic light.

A reflector with a so-called anti-phantom cross consists of mutually perpendicular segment plates with slots for the location of a halogen lamp (Fig. 1).

A ray of light incident on the reflector from an external light source is deflected and absorbed by the surface of the plates. Another solution is carried out by installing a special anti-phantom lens in front of the light filter 1, consisting of two parts 2, 3, each of which has a sawtooth profile (Fig. 2). A ray of sun falling on an inclined surface is thrown onto a horizontal blackened step and absorbed by it.

Rice. 16 - Anti-phantom cross

Fig. 17 - Lens absorbing sunlight

Red means “stop”, green means “go”, yellow means “hurry up and turn that damn green already!” Why these particular colors? Why not blue, purple and brown, for example?

The answer to this question, as it turned out, was a little confusing, but it still made some sense. The very first traffic lights appeared for drivers, not for motorists. They consisted of red and green barriers that were lowered in front of the gas lamp, which was quite dangerous in case of leakage.

Red came from the train tracks

The color red symbolizes danger in many cultures, which is scientifically explained as follows: its light wave is the longest among all visible colors of the spectrum. This means that you will be able to see such a signal from as far away as possible. Thus, the color red meant “stop” long before the advent of cars. Ever since it replaced mechanical “wings” that rose and fell to signal whether the path was clear. So, with that out of the way, it's not that difficult.

Green primarily means “Attention!”

But the role of green signals has changed over time. The wavelength of light for green is shorter and follows immediately behind yellow in the visible spectrum. This means that it can be seen from greater distance than any other color other than red or yellow. In the days of the first railway traffic lights, green meant “Attention!”, and permission to travel was given to white people. But to stop a train, a driver needs much more time than a car driver. And after several major train collision accidents occurred because the driver confused the bright light of a star with the “Road Clear” signal, only two colors remained in service: red and green.

Yellow means "Attention" because it is almost as visible as red

With the advent of automobiles until the mid-90s, not all stop lights were red, some were yellow. It was decided to do this for the reason that at night in a poorly lit area it was difficult for drivers to notice the light barely escaping from behind the red filter. For a long time, only yellow was used to indicate the need to stop. It started in Detroit in 1915, a city that 5 years later installed the first electric traffic light with an “amber” color.

But what happened to the original yellow signal? With the advent of electricity and new possibilities, the need to use it as a stop signal instead of a red one disappeared. Therefore, the color remained as a sign warning that it was necessary to prepare.