In the 1991 Random House book "Ever Wonder Why?" by Douglas B. Smith, the following question is answered: (Click on book title to purchase)
"Ever Wonder Why most Traffic Signals and Markers are Yellow?"
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Answer: " Yellow is the most visible of all the colors in the spectrum. It can be seen from the farthest distance and is conspicuous in all lighting conditions. This makes it a natural choice for traffic signals, which must be seen from great distances." (pg. 52)
School buses, heavy roadside equipment, and most taxi cabs in the US are also painted yellow for this very same reason.
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Two Dept. of Energy physics professors also help us understand why amber light is superior, when they answer the question:
Why Are Fog Lights Yellow? (source link here)
Our eyes are not equally sensitive to all colors… we are most sensitive to yellow and green…
So, our best compromise between sensitivity for our eyes and a long wavelength for (the) least scattering* is yellow light.
Richard Barrans Jr., Ph.D.
(*Fog particles are, or were at one time, believed to scatter light)
...Thus to obtain the greatest penetration of light through fog, you should use the longest wavelength possible. Red is obviously unsuitable because it is used for stop lights. So you compromise and use yellow instead.
...The other explanation is that someone deemed it desirable to make fog lights yellow as a way of signaling to other drivers that visibility is poor and thus caution is in order.
Dr. Lawrence D. Woolf - General Atomics
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Two vehicles traveling in fog. The fog seems to be scattering some of the output from the white headlights. Notice, if you look closely, you can barely see the red tail lights directly to the right of the car with its headlights on. |
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Car in heavy rain: The worse the environmental conditions get, the better AMBER lighting seems to stand out. This Ferrari race car has both yellow headlights and lightly tinted yellow plexiglass headlight covers. |
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From a science/physics viewpoint, Why AMBER? |
Experts explain that the human eye is most sensitive to light in the middle visible light wavelengths of the spectral range [yellows and greens; between 550-600 nanometers]. Our eyes actual perceives these colors as being brighter, when compared to an equavalent amount of radiant energy emanating from some other color of light, as is proven by the science of photometry.
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Try this: Walk across the room, and then quickly glance back at your computer screen to view the above image from a distance. Which color 'pops out' to you first? |
Today, our societies contain what some have called a ‘sight and sound’ generation. A sound analogy can help explain why AMBER light is so effective with respect to the human eye.
The human ear can hear frequencies between 20 Hz and 20,000 Hz, yet we speak to each other in the midrange frequencies right around 1000 Hz. We sometimes have problems hearing the extreme ends of the spectrum [the highs and lows, especially as we get older], but we, as human beings, hear the midrange sound frequencies very, very well.
Similarly, we ‘see’ the midrange color frequencies like yellow and green very well, and don’t always see the ends of the spectrum as well (red and violet/blue). Hence, AMBER appears brighter when compared with an equal energy output amount of just about any other color of light, including white.
Some sources say that the human eye is basically 'amber seeking': that we will scan any new environment we enter into, and immediately seek out the AMBER or bright yellow items in that environment first.
Take a look at the video below, where a company has developed an amber flashing LED safety lamp for cyclists, to take advantage of this science.
Notice, when the video starts, how your eyes are drawn to this gentleman's bike lamp even before noticing the other things in the surrounding environment. Even the moving car on the street to the right of the bike does not initially command as much attention as the stationary flashing amber light does.
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| Video of a bicycle rider actually avoiding a frontal collision with a minivan because of AMBER LED daytime safety lighting. | _______________________________________________________________
Seasoned Outdoor Billboard advertising specialists also often admit their clients get more sales traffic from billboards with yellow backgrounds
In an online article titled "How to use Colors that will Appeal to Consumers", outdoor advertising specialist Selena McIntyre writes the following on the OutdoorBillboard.com website:
"Yellow is a perfect color for sunny, happy, bright, cheerful, playful, easygoing, and optimistic advertisements. Ideal for florists, candy shops, toy stores, amusement parks, and discount stores.
Yellow is the first color the eye processes. It is also the most visible color to the human eye. This is why it grabs attention faster than any other color.
Yellow is also a color of caution. Most yellow road signs are warning drivers of a problem in the road or with the on-coming traffic. This is just another reason why yellow grabs our attention quickly."
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Outdoor billboard in yellow; color used to maximize consumer attention, which in turn maximizes ad-generated revenue | _______________________________________________________
Did you know that some of the first instances of AMBER DRLs could be found in Sweden in the 1970's.
Shown below are add-on, aftermarket dedicated DRL lamps made by the German lighting company Hella and sold into Sweden. They were amber in output to help command increased attention from other roadway users, and to command more attention than a vehicle's regular white light headlights could offer.
When these lamps first came to market, they were reportedly known as 'verselljis', which means 'perception light' or 'notice light'.
The writing on the package shown below translates: "Install Hella perception lights so you are seen in traffic".
As early as the 1970's, it appears that even lighting scientists who studied the issue of daylights back than, knew that during daytime hours AMBER is just better.
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Early model retrofit AMBER DRLs, designed to increase vehicle conspicuity, were due in part to one of the first widespread DRL laws that occured more than 30 years ago. |
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