Knowing the Science of Light Makes Choosing the Right Color Clear as Day

Marni Epstein SPECIAL TO CEG - May 2019

Have you ever thought, “wow that vehicle's green light seems brighter than its other lights?” You aren't imagining it; there is a scientific reason why. Let's geek out for a second:

A typical human's (with no color vision deficiency) color viewing sensitivity can see and discern across a wide range of colors over the “visible spectrum.” In a rainbow, for instance, the visible color spectrum range we see and discern is from violet/blue (shorter wavelength) to red (longer wavelength). Green falls generally in the middle…but what does this have to do with green lights?

The terminology used to describe wavelength is in meters, but because the value is so small, nanometers (nm) is the range of the actual wavelength unit values. The numerical values of typical human visual range is approximately 380 nm (violet/blue) to 800 nm (red/near infrared).

The LEDs (light emitting diodes) used to make green light produces wavelength energy between 520 nm and 540 nm, which is very close to the peak of our human visual color sensitivity (555 nm for our photopic or “day time” vision). Peak visual color sensitivity explains why we are easily able to discern the green color (color discernment as a signal light), as compared to “typical” emergency light coloring of blue or red.

Now that you know why green is so noticeable, you might be asking yourself, what other vehicle signal lighting color is next closest to the human visual peak? It is Amber, which — depending on the specific LED — produces energy between 585 nm and 600 nm. With those values, amber is just on the other side of our peak sensitivity from green. Because of the way green and amber flank the visual peak, we are a little more sensitive to amber in the daytime and see green a little better in the night. Recent years have seen state agencies across America specify combinations of green with amber for road maintenance equipment, for the best visibility and safety with motorists. Now we know why!

SoundOff Signal has been on the forefront of helping write specifications for vehicle lighting across many industries. As a global manufacturer of vehicle lighting products specifically in the Local, State and Federal Law Enforcement, Emergency, First Responder, and Amber industries such as Municipal, DOT, Towing, Utility, Construction, etc…, we understand the challenges of high visibility for improved safety in all types of weather conditions and day versus night time.

“Understanding the science behind the human visual response and human reactions to lighting and color is extremely important in developing high quality effective lighting that is not just bright and flashing, ultimately improving safety and saving lives,” said Doug Baker, chief innovation officer of SoundOff Signal.

To ensure the right product is being presented to meet the right need in the right market, we look at lighting products and how they visually communicate, we ask “when are they a safety feature and when are they a distraction or safety hindrance?” Our controls systems in conjunction with our lights are intelligently designed to help improve safety by conditionally programming the lights based on the scene requirements.

SoundOff Signal offers a complete suite of amber and green LED lighting and controls products like its rugged nRoads products and durable silicone mPower products that solve vehicle visibility needs.

For more information, visit www.soundoffsignal.com, or contact Gabe Casucci at gcasucci@soundoffsignal.com or 716/553-4431.