Not just red, amber and green, traffic lights will have a new ...

The traffic lights on the roads may not appear as they used to any more. For more than a century, the traffic lights have been known to have only three colours - red, amber and green. 

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However, they are now likely to have a fourth colour after scientists suggested that adding another colour will help traffic flow near driverless vehicles. 

Autonomous vehicles (AV) are a new concept and no completely driverless cars have made it to the road yet. 

Self-driving taxi firm Waymo is close to finalising what is called SAE4 in California and Arizona and other companies like Tesla are also producing self-driven vehicles. 

As of now, the government has not allowed self-driven vehicles on UK roads but they are soon to make their debut after the Automated Vehicles Act is passed.

When the act is passed, the roads will see a mix of driverless vehicles and human-steered cars. 

White traffic light for self-driving cars

To ensure that the traffic moves smoothly, the North Carolina State University's engineers have proposed what is called a &#;white light&#; at traffic lights that allows self-driving cars to help when there is a traffic flow and allow human drivers to understand what is happening.

Study lead Dr Ali Hajbabaie said that the plan was to get into the computing power of the AVs and understand which vehicles are where.

"The white phase concept incorporates a new traffic signal so that human drivers know what they are supposed to do," Hajbabaie said.

"Red lights will still mean stop. Green lights will still mean go. And white lights will tell human drivers to simply follow the car in front of them," he added. 

The paper was published by Dr Hajbabaie and his team in the Journal of Computer-Aided Civil and Infrastructure Engineering. 

The team formed a series of computer simulations which helped in visualising how the new traffic light system will work. 

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According to the system, the AVs were expected to communicate with each other wirelessly and with the computers which are controlling the traffic signals. 

At the time when AVs approach the intersection, the computers will activate the new traffic light system.

The white light will be an indication that the AVs are coordinating their movements through the intersection and all non-automated vehicles will have to follow the vehicle ahead. 

Link to FAMA

Dr Hajbabaie said that the system will improve travel time as well as fuel efficiency and will ensure the safety of everyone on the roads. 

"If at some point in the future we see almost universal adoption of AVs, our models suggest that delays at intersections would decrease by more than 25%," Dr Hajbabaie said. 

"More realistically, we will eventually see a lower percentage of wirelessly connected AVs on the road, but there would still be meaningful improvements in traffic time," he added. 

(With inputs from agencies)

Red means "stop," green means "go," and yellow means "hurry up and make that damn light." Why those colors, though? Why not blue, purple, and brown? I have to admit that aside from a hunch that it had to do with wavelengths, I had no idea myself, so I decided to look into it.

The answer, as it turns out, is a little convoluted, but makes sense. The earliest traffic signals were designed for trains, not cars. They were red and green, gas-powered, and more than a little dangerous in the event of a leak.

Red is an inherited symbol from railroads

Red symbolizes danger in many cultures, which makes sense, considering it has the longest wavelength of any color on the visible spectrum, meaning you can see it from a greater distance than other colors. With the ironic exception of stop signs (not stop lights, just signs -- more on that in a second), red has meant stop since long before cars existed, with train signals' use of red dating back to the days when mechanical arms lifted and lowered to indicate whether the rail ahead was clear. So that one's simple.

Green meant "caution" at first

Green's role in lights has actually changed dramatically over time. Its wavelength is next to (and shorter than) yellow's on the visible spectrum, meaning it's still easier to see than any color other than red and yellow. Back in the early days of railway lights, green originally meant "caution," while the "all-clear" light was, well, clear or white. Trains, of course, take an interminably long time to stop, and legend has it that several disastrous collisions happened after an engineer mistook stars in the night horizon for an all-clear. Thus, green became "go," and for a long time, railways used only green and red to signal trains.

Yellow means "caution" because it's almost as easy to see as red

From the earliest days of motoring up until the mid-s, not all stop signs were red -- many were yellow, along with yield signs, because at night it was all but impossible to see a red stop sign in a poorly lit area. The yellow stop-sign craze began in Detroit in , a city that five years later installed its first electric traffic signal, which happened to include the very first amber traffic light, at the corner of Michigan and Woodward Aves.

But what of those weird yellow stop signs, you ask? As materials and technologies evolved, the ability to produce highly reflective signs meant that red could resume its natural spot in the sign hierarchy, leaving the still-highly-visible yellow (it's second only to red in terms of visible wavelength) to the domain of "caution." That's why school zones and buses, crosswalks, and other important warnings are yellow today.

Red means "stop," green means "go," and yellow means "hurry up and make that damn light." Why those colors, though? Why not blue, purple, and brown? I have to admit that aside from a hunch that it had to do with wavelengths, I had no idea myself, so I decided to look into it.

The answer, as it turns out, is a little convoluted, but makes sense. The earliest traffic signals were designed for trains, not cars. They were red and green, gas-powered, and more than a little dangerous in the event of a leak.

Red is an inherited symbol from railroads

Red symbolizes danger in many cultures, which makes sense, considering it has the longest wavelength of any color on the visible spectrum, meaning you can see it from a greater distance than other colors. With the ironic exception of stop signs (not stop lights, just signs -- more on that in a second), red has meant stop since long before cars existed, with train signals' use of red dating back to the days when mechanical arms lifted and lowered to indicate whether the rail ahead was clear. So that one's simple.

Green meant "caution" at first

Green's role in lights has actually changed dramatically over time. Its wavelength is next to (and shorter than) yellow's on the visible spectrum, meaning it's still easier to see than any color other than red and yellow. Back in the early days of railway lights, green originally meant "caution," while the "all-clear" light was, well, clear or white. Trains, of course, take an interminably long time to stop, and legend has it that several disastrous collisions happened after an engineer mistook stars in the night horizon for an all-clear. Thus, green became "go," and for a long time, railways used only green and red to signal trains.

Yellow means "caution" because it's almost as easy to see as red

From the earliest days of motoring up until the mid-s, not all stop signs were red -- many were yellow, along with yield signs, because at night it was all but impossible to see a red stop sign in a poorly lit area. The yellow stop-sign craze began in Detroit in , a city that five years later installed its first electric traffic signal, which happened to include the very first amber traffic light, at the corner of Michigan and Woodward Aves.

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