What is traffic lights/ Signals? Who Invented and where it is situated first?

We all know what is traffic light because daily we using it on our road for intersection it may be in small town city or metro city.Before knowing about all history about traffic lights first we know what’s traffic light or signals.Traffic lights, also known as traffic signals or traffic lamps and traffic control signals are signalling devices positioned at road intersections, pedestrian crossings, and other locations to control flows of traffic.Traffic lights allow for intersecting roads to exist without cars crashing, bikes and other vehicles into each other.

                    They are usually yellow or black and have three lights emitting the colors red, yellow (Amber), and green. Red means ‘stop’, yellow means ‘slow down’ and green means ‘go’. Oftentimes, the yellow is often inferred as the opposite meaning, being ‘speed up’ as most drivers are impatient and don’t want to get stuck behind a red light. The internal clock of a traffic light corresponds directly to the internal clock of a cross signals. In most modern cross signals, after flashing a ‘walk’ symbol, a countdown will appear with a flashing orange hand, signalling pedestrians to cross faster. The timer varies from 15–30 seconds (may vary), and despite the clock saying differently, there is still a 5-second pause between a the timer reaching 0 and the light turning green.

                      The world’s first, manually operated  traffic signal was short lived. Installed in London in December 1868, it exploded less than a month later, injuring or killing its policeman operator. Traffic control started to seem necessary in the late 1890s and Earnest Sirrine from Chicago patented the first automated traffic control system in 1910. It used the words “STOP” and “PROCEED”, although neither word lit up.

                    Traffic lights alternate the right of way accorded to users by displaying lights of a standard colour (red, amber (yellow), and green) following a universal color code system. In the typical sequence of colour phases as follows.

  • The green light allows traffic to proceed in the direction denoted, if it is safe to do so and there is room on the other side of the intersection.

  • The amber (yellow) light warns that the signal is about to change to red. In a number of countries a phase during which red and yellow are displayed together indicates that the signal is about to change to green. Actions required by drivers on a yellow light vary, with some jurisdictions requiring drivers to stop if it is safe to do so, and others allowing drivers to go through the intersection if safe to do so.

  • A flashing amber indication is a warning signal and indicates that drivers may pass if no pedestrians are on the crossing.

  • The red signal prohibits any traffic from proceeding.

  • A flashing red indication is treated as a stop sign.

In some countries traffic signals will go into a flashing mode if the Conflict Monitor detects a problem, such as a fault that tries to display green lights to conflicting traffic. The signal may display flashing yellow to the main road and flashing red to the side road, or flashing red in all directions. Flashing operation can also be used during times of day when traffic is light, such as late at night.Well now we known about the traffic lights and what’s it indicates by different colour of light. Let’s see some history.Before traffic lights, now a days also in many countries in small town if there is less traffice a traffic police man controlls the flow of traffic. Two or Three men were given the task of directing traffic.

               On 9 December 1868, the first non-electric gas-lit traffic lights were installed outside the House of Parliament in London to control the traffic in Bridge Street, Great George Street, and Parliament Street. They were proposed by the railway engineer J.P. Knight of Nottingham who had adapted this idea from his design of railway signalling systems and constructed by the railway signal engineers & Farmer. The main reason for the traffic light was that there was an overflow of horse drawn traffic over Westminster bridge which forced thousands of pedestrian to walk next to the Houses of Parliament. The gas lantern was manually turned by a traffic police officer with a lever at its base so that the appropriate light faced traffic. The signal was 22 feet (6.7 m) high. The light was called the semaphore and had arms that would extend horizontally that commanded drivers to “Stop” and then the arms would lower to a 45 degrees angle to tell drivers to proceed with “Caution”. At night a red light would command “Stop” and a green light would mean use “Caution”.

Although it was said to be successful at controlling traffic, its operational life was brief. It exploded on 2 January 1869 as a result of a leak in one of the gas lines underneath the pavement and injured the policeman who was operating it.

                   In the first two decades of the 20th century, semaphore traffic signals like the one in London were in use all over the United states with each state having its own design of the device. One example was from Toledo, Ohio in 1908. The words “Stop” and “Go” were in white on a green background and the lights had red and green lenses illuminated by for night travelers and the arms were 8 feet (2.4 m) above ground. It was controlled by a traffic officer who would blow a whistle before changing the commands on this signal to help alert travelers of the change. The example in Ohio was the first time America tried to use a more visible form of traffic control that evolved the use of semaphore. The device that was used in Ohio was designed based on the use of railroad signals.

                  In 1912, a traffic control device was placed on top a tower in Pais at the Rue Montmartre and Grande Boulevard. This tower signal was manned by a police woman and she operated a revolving four-sided metal box on top of a glass showcase where the word “Stop” was painted in red and the word “Go” painted in white.

An electric traffic light was developed in 1912 by Lester Wire a policeman in Salt Lake City, Utah, who also used red-green lights. On 5 August 1914, the USA Traffic Signal Company installed a traffic signal system on the corner of East 105th Street and Euclid Avenue in Cleveland, Ohio.It had two colors, red and green, and a buzzer, based on the design of James Hoge, to provide a warning for color changes.The first four-way, three-color traffic light was created by police officer William Potts in Detroit, Michigan in 1920. The tower was the first innovation that used the three-colored traffic signal and appeared first in the City of Detroit. where the first three-colored traffic light was built at the intersection of Michigan and Woodward Avenues in 1920. The man behind this three-color traffic light was police officer William Potts of Detroit.

              Los Angeles installed its first automated traffic signals in October 1920 at five locations on Broadway. These early signals, manufactured by the Acme Traffic Signal Co., paired “Stop” and “Go” semaphore arms with small red and green lights. Bells played the role of today’s amber or yellow lights, ringing when the flags changed—a process that took five seconds. By 1923 the city had installed 31 Acme traffic control devices.

             The first interconnected traffic signal system was installed in Salt lake city in 1917, with six connected intersections controlled simultaneously from a manual switch. Automatic control of interconnected traffic lights was introduced March 1922 in Houston, Texas.

             In1922 traffic towers were beginning to be controlled by automatic timers. The first company to add timers in traffic lights was Crouse-Hinds. They built railroad signals and were the first company to place timers in traffic lights in Houston which was their home city.

The first traffic lights in Britain were deployed in Piccadilly circus in 1926.  Wolverhampton was the first British town to introduce automated traffic lights in 1927 in Princes Square at the junction of Lichfield Street and Princess Street. Melbourne was the first city in Australia to install traffic lights in 1928 on the intersection of Collins and Swanston Street.

            The first traffic light in South India Swas installed at Egmore Junction, Chennai in 1953. The city of Bangalore installed its first traffic light at Corporation Circle in 1963.

           The control of traffic lights made a big turn with the rise of computers in America in the 1950s. Thanks to computers, the changing of lights made Crosby’s flow even quicker thanks to computerized detection. A pressure plate was placed at intersections so once a car was on the plate computers would know that a car was waiting at the red light. The rise of computers is the model of traffic control which is now used in the 21st century.

        Countdown timers on traffic lights were introduced in the 1990s. Timers are useful for pedestrians, to plan whether there is enough time to cross the intersection before the end of the walk phase and for drivers, to know the amount of time before the light turns green. In the United States, timers for vehicle traffic are prohibited, but pedestrian timers are now required on new or upgraded signals on wider roadways.

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