The "Nine-grid" traffic light is a misunderstanding! What happened to the traffic lights to become like this?

Recently, the "Nine-grid" traffic light has become a hot topic, but it was finally confirmed to be a false alarm. The design of traffic lights is related to people's travel. Do you know when it first appeared? Why did they choose red, yellow and green?

Compiled by New Media Editor Lv Bingxin

Recently, the "new version of the nine-square grid traffic light" has attracted widespread attention. In the eyes of many netizens, the new rules are numerous and difficult to remember, which undoubtedly increases the difficulty of judgment.

▲The so-called "new national standard traffic light" circulated on the Internet is also called the "nine-square grid" traffic light by netizens

Subsequently, the Traffic Management Science Research Institute of the Ministry of Public Security refuted the rumor. It is understood that the current national standard "Road Traffic Signal Light Setting and Installation Specification" (GB14886) was issued on December 13, 2016 and implemented on July 1, 2017. It has been 5 years since then and has not been revised. There is no "new national standard" to be implemented in 2022. At present, the road traffic lights in use in various places meet the current standards and do not need to be replaced.

In the discussion about this incident, many questions aroused everyone's curiosity about traffic lights. When did the traffic light first appear? Why did they choose red, yellow, and green? Where does the electricity for the traffic light come from, and why does the power go out?

Born to command the "carriage",

Traffic lights have only been around for a hundred years

It seems that traffic lights have been around for as long as our generation can remember. But in fact, they have only been around for more than 150 years. Until 1868, there were no traffic lights in the world that were officially put into use.

At that time, horse-drawn carriages were already popular in Britain, and people were often run over. But how to manage traffic? There were so many cars and roads that there were not enough police to manage them all. In other words, traffic lights were originally designed to control "horse-drawn carriage traffic."

So in December of that year, the world's first manual gas-lit traffic light was born in the UK.

(Picture from the Internet)

It is said that the traffic light was inspired by the design of women's clothing by JP Knight, a British railway signal engineer: women wearing red clothes represent married people, while women wearing green clothes represent unmarried people.
Unfortunately, the lamp only lasted 23 days because a gas lamp exploded and killed a policeman.

It wasn't until the late 1890s, when the Second Industrial Revolution was complete, that electric-powered traffic lights arrived.

(Picture from the Internet)

In 1914, the first electrically-activated traffic light appeared. At that time, cars had already become popular on the streets. A traffic light on a tall tower on 5th Street in New York City could easily tell the endless stream of people: Stop when the red light is on, and Go when the green light is on.

Another interesting design advancement is that the American traffic light company Lester Wire added a buzzer to the traffic light, which would remind people that the color would change before the light switched.

(Picture from the Internet)

The "countdown" that is supported by everyone today has the same purpose. It was not introduced until decades later in the 1990s.

Two lights become three lights,

When did the yellow light appear?

As technology developed faster and faster, the world's first automatically controlled traffic light appeared in Toronto, Canada in 1963. Traffic police only needed to sit in the office to uniformly control and monitor traffic conditions.

At that time, the world's traffic lights only had two colors: red and green. As traffic conditions became more and more changeable and cars drove faster and faster, using two colors to control traffic was obviously not enough.
So, inventors began to think about new designs for traffic lights - and this is when the yellow light came into play.

However, there are different opinions about who invented the yellow light: one opinion is that in 1920, William Potts, a police officer in Detroit, Michigan, invented a multifunctional traffic light with a yellow light, which was put into use in Detroit in October 1920; another opinion is that in 1927, a Chinese man named Hu Ruding was almost "hit" by a car when he was crossing a street with a green light, so he came up with the idea of ​​a yellow traffic light, which was later adopted by the US government.

(Image source: Unsplash)

So the question is, why are red, yellow and green the most suitable colors for traffic lights?
Dr. Sun Ruoduan from the Institute of Optics and Laser Metrology of the National Institute of Metrology said that red and green have very different hues, so they are easier for us to distinguish. On the hue circle, the yellow area is exactly in the middle of the red and green areas, which ensures that there is a clear hue difference from red and green.

(Pictures from the Internet)

Why is blue, which is in the middle area on the other side of the hue ring, not suitable as the color of traffic lights?

Sun Ruoduan introduced that this has something to do with the history of the development of traffic lights. No matter whether it is a gas lamp or an electric lamp, they are all lamps based on the principle of thermal radiation luminescence, and the component of the blue spectrum will be relatively low. In this case, the traffic lights are likely to be very weak and not easy to be discovered by pedestrians, thus causing more traffic accidents.

Lighting technology is becoming more mature.

The third generation of traffic lights appears

From kerosene traffic lights to electric traffic lights, the second generation of traffic lights lasted for more than a hundred years.
It was not until the late 1990s that semiconductor lighting technology gradually matured and the third generation of traffic lights appeared.

(Image source: Unsplash)

It is the LED traffic light, which is not only energy-saving and not easy to damage, but also more efficient.
After that, the design of traffic lights became more and more diverse. For example, the self-service pedestrian crossing signal lights, which turn green when people want to cross the road; lane indicator lights with arrows; countdown traffic lights, arrow indicators that can change direction, and flashing warning indicator lights also gradually appeared...

But people occasionally find that traffic lights malfunction due to lack of power. Why is this?

Most traffic lights are powered by electricity from the power grid. Traffic lights powered by electricity meters installed by power supply companies have "identities" and the meter numbers can be checked. The power supply companies have a clear understanding of their operating conditions. A small number of traffic lights are mobile solar traffic lights.

However, there are still many traffic lights that meet the regulations but are "illegal". They "borrow" electricity from nearby sources, and the sources are also varied: nearby street lights, enterprises, public substations, etc. The power supply companies usually do not know the operating conditions of these traffic lights.

Traffic light outages are usually related to two situations:

One is planned maintenance. In this case, the power supply company will issue a power outage notice in advance.

For traffic lights with "status", the power supply company is aware of whether the planned maintenance will affect the operation of the traffic lights and will notify the traffic management department in advance to prepare;

As for those "black household" traffic lights, although it is difficult for the power supply company to know which traffic lights will be affected by the power outage, they will inform the customer managers of each special transformer, municipal departments or traffic management departments in advance, and make judgments and prepare according to the information they have.

Also, when a traffic light malfunctions, the traffic control department will generally use emergency traffic lights or send traffic police to assist at the intersection, while the power supply company will speed up operations to get the traffic lights back in operation as soon as possible.

Cool Fact: How big are traffic lights?

A question, how big do you think a traffic light is? As big as a palm? As big as a washbasin? Or as big as an office desk?

Many people thought it was just averagely big, until one day, when they saw two workers setting up a scaffolding to replace the traffic light: the friends were all stunned, ah, the traffic light turned out to be so big!

(Photo source: YiDu)

Why is the traffic light so big?

There are several common types of traffic lights in China, including motor vehicle lights, non-motor vehicle lights, pedestrian crossing lights, etc. According to the form of traffic lights, they can be divided into direction indicator lights, flashing warning lights, merging traffic lights, etc. There are many types of traffic lights, and the sizes are also varied. According to the "Road Traffic Lights" (GB14887-2003) and the "Road Traffic Lights Setting and Installation Specifications" (GBM886-2006), my country has not made unified regulations on the specifications of traffic lights, and each region has its own regulations.

For example, the most common 400-type traffic light is 1.5 meters long, and with the frame it reaches the eye level of many people:

(Photo source: YiDu)

The 300-type traffic lights are commonly used in non-motorized vehicle lanes. The height is about 1 meter, reaching the height of a person's chest:

(Photo source: YiDu)

There are also 401, 403, 100, 103, etc. The models of traffic lights vary, but the height of motor vehicle signal lights is basically concentrated between 1.3 meters and 1.7 meters. The huge traffic light at the beginning of this article, which is a little taller than a person, should be a 1.7-meter light. It doesn't look big hanging there, but in fact it is as tall as the average height of Chinese men (1.71 meters) and exceeds the height of most women (average 1.59 meters).

(Photo source: YiDu)

(Source: iFanr, CCTV Finance, Science Popularization China, YiDu WeChat public account, etc.)

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