They’ve closed a major road going through Harpers Ferry and due to the closure lots of the traffic is re-routing through Shepherdstown. There is no traffic light in Shepherdstown — only a 4-way stop, and traffic is really backing up especially during the morning and evening “rush” hours. Someone mentioned that the 4-way stop should be replaced with a traffic light.
Well….. that got me to thinking about traffic lights. Maysville, Oklahoma, where I grew up didn’t have a traffic light — except for a few months. The traffic light that they installed just had a green light and a red light — no yellow light. But it was only in operation for maybe a couple of months when a big truck hit it and it had to be taken down for repairs — and never got put back up. It was never popular anyway and people thought that the few cars in Maysville could get through the main intersection and not run into each other without a traffic light.
But my wondering about traffic lights was — why did they choose red, green and yellow for the colors, and how did they get everyone to agree to use those colors? I’m pretty sure if traffic lights were being invented today, Congress and the States wouldn’t be able to agree on a common color scheme….
Well, it turns out that when traffic lights first came into being, there was no “standard,” and there were various schemes used to control traffic around the country. The Federal Highway Administration published “The Manual on Consistent Traffic Control Devices” in 1935 to define uniform standards for all road signs, pavement markings and traffic signals — mandating them to all employ red, yellow and green light colors.
So I guess that’s how consistency was mandated, but what about the colors? I’m not sure but I think science must have played a big part in the color choices….. If you remember, there are seven colors in the light spectrum — and the wavelengths increase from violet, the shortest, to red, the longest. Back in general science classes, we learned that longer wavelengths have shorter frequencies and tend to travel longer distances. When you look at different colors, red has the longest wavelength followed by yellow, and then green.
So it appears that the colors with the longest wavelengths were chosen for traffic signals because they could be seen at a greater distance.
The three colors of the traffic light were assigned in priority. Red for stop because a driver should be alerted as soon as possible of danger and to come to a stop. Yellow was chosen to warn drivers, and green, for go, maybe because it’s not so urgent for driver to go as it is to stop.
So once again, science comes to the rescue……
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