![]() Automated or timed lights started to appear around 1922. The original signals were operated by policemen. Of course, you need a wide viewing angle, and there is usually some sort of visor to help prevent the sun from washing out the color. Then again, LEDs don’t melt snow off the lights like the old bulbs did. How do you maximize incandescent bulb life? You derate the bulbs and keep a slight current flowing through them all the time so the filaments stay warm, minimizing thermal shock when you turn them on again. Then there are all the technical issues the public never thinks about. Adler also came up with the pedestrian push button in 1929. That would seem to have some problems operationally, but it did serve as a foundation for lights that respond to vehicle traffic. In 1928, he perfected a system that allowed drivers to honk to change the light. Charles Adler is another name in traffic light history. Like many inventions, there wasn’t a single inventor for the modern device. The original prototype is in the Smithsonian’s American History Museum. Morgan’s invention was cheaper to produce than the Potts design, and he sold the rights to General Electric for a cool $40,000 - quite the sum in those days. This “caution period” between go and stop would become a standard for traffic signals of all kinds. Morgan’s traffic signal relied on using arms labelled “stop” and “go”, but importantly also included the pause to stop traffic in all directions until the intersection could clear. This is advantageous in that vehicles which are partly across the intersecting streets are given time to pass the vehicles which are waiting to travel in a transverse direction thus avoiding accidents which frequently occur by reason of the over-anxiety of the waiting drivers, to start as soon as the signal to proceed is given. One of the objects of my invention is the provision of a visible indicator which is useful in stopping traffic in all directions before the signal to proceed in any one direction is given. He noted that the traffic signals of the day would abruptly change from “go” to “stop” and decided a third state would solve the problem. The Army used these hoods in World War I.īut back to traffic lights, Morgan was driving through Cleveland one day and saw an accident. He and his brother would use the hoods to rescue two people trapped underground after a gas explosion in 1916. He also invented several things, including a hair relaxer that came from a solution used to prevent sewing machine needles from overheating, and a firefighter’s safety hood that routed cool air from floor level to the user in 1914. Morgan was the first African-American to own a car in Cleveland. Yet another system to include a pause state was invented by Garret Morgan. Borrowing from the rail system, the first yellow light appeared when policeman William Potts added it to signals in Detroit in 1920. Cars can’t stop instantly, and if the side with green starts moving before the side with red stops, they collide. The fundamental problem with the red/green system is that of inertia. A 1917 patent by William Ghiglieri also had two lights - red and green. ![]() Two years later, Lester Wire, a police officer, developed a different version powered by overhead trolley wires to light the signal. In 1910, American inventor Ernest Sirrine worked out an automatically controlled traffic signal. A gas leak caused one of the lamps to explode, badly burning the operator and ending the nascent invention for a while. The semaphore had gas lamps to illuminate the signs in the dark. The initial test of the signal proved disastrous. The traffic light is a ubiquitous feature of modern life and is quite old - dating back to 1868 London, although that device was a modified railroad semaphore operated by a policeman, but it was the same idea. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |