Red, Yellow, Green

The history of traffic lights, their colors, and their colors’ meanings.

The simple, unassuming traffic light is something that most of us see (or at least would see before Covid) everyday. However, if you’ve ever tried to get to Dickson City from lower Dunmore/Scranton, you have a special understanding of what it means to stare at a red light while waiting at that one-way bridge on East Parker Street. One particular evening I sat just there as my eyes nearly turned to raisins from what felt like an eternity of unconsciously staring at the piercing red light. After waking from my post-work space out session I began to wonder… it seems so obvious to associate red with stop and green with go… but why? Obviously most of us can point to traffic lights as the obvious reason for this, however it wasn’t always this way, at least not exactly.

The first gas powered, man-operated traffic lights were invented in the mid 1800s, with London installing the first one for public use in 1868. Prior to this, police would conduct the flow of traffic, however the lights would inevitably replace them with the police manning the controls. Oddly enough, the first traffic light only lasted a mere month after it would explode due to a gas leak, killing the officer controlling it in the process. Its reason for invention was to help control the nighttime flow of foot traffic outside the Parliament building, as an overwhelming amount of carriages were preventing walkers from crossing the street in excess.

So, how did the colors of traffic lights become associated with their respective meanings? Well, it’s not as simple as yellow meaning slow and green meaning go, but one thing is for sure: red has always been a universal symbol for danger, particularly in that of world of semiotics and design work.

My own personal theory as to why red is inherent to danger would have to be our association of it with the color of blood, or perhaps fire as well, yet that is besides the point. Red was almost always used as a symbol of danger on railways, and before public roads and 19th century infrastructure were introduced, trains were the main method to transport both people and goods, so naturally roadways found it easier to borrow from their colors. Outside of red, blue, white, and green were often used to signal “proceed” and strangely, green was sometimes meant to represent “proceed with caution” the same way a flashing yellow light would signal that to us. After enough accidents, a universal system of red meaning stop, green meaning proceed with caution, and bizarrely enough, white meaning go. This would shape shift into the system of color schemes we are currently accustomed to, but it wasn’t without its fair share of errors in it’s own right.

Initially, green and white could both represent “go,” due to white long being associated with proceeding at traffic signals, however in 1914 green would become the universally accepted color for “go” after an accident when the red covering of the light fell off leaving a translucent circle in its place, leading a carriage to crash at the sight of what they believed was a light indicating them to go. So out of convenience, green would become the color! Six years later, after witnessing an accident, the African American inventor Garrett Morgan would invent the first three-position traffic signal, adding the third color and safer measures to stopping on the roads. Timers would be implemented the same year.

Drawing of the first London traffic light

So hopefully now we all know a little more about traffic lights and why certain elements of design and color coalesce to form specific norms and precedents. There is quite literally an infinite amount of things to question and wonder about, and who knew I would find myself so wrapped up in something that most people hope to never stare at? And while we’re at it, why not take a moment to appreciate the work of French Sculptor Pierre Vivant!

Pierre Vivant, Traffic Light Tree, 1998

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