How much does a traffic light weigh

 Traffic lights, big and small, how much does a traffic light weigh, the need to points. Now in almost every intersection traffic lights, which is "traffic cop" don't make any noise. The traffic light at the traffic light is an international unified. The red light is stop signal, a green light is a signal. Intersection, car from several directions to collected here, some want to go straight, turn to, who let go first, that is to obey traffic lights command. Red light, go straight or turn left, without hinder pedestrians and vehicles, allowing vehicle right; Green light, allowing cars go straight or turn; Yellow light, stop at the intersection to stop line or crosswalk line of less than, has continued to pass; Yellow light flashing, pay attention to safety warning vehicle. I think for this kind of effect on human life is a big thing, cannot be simply measured by how much does a traffic light weigh, more major is to explain the status of traffic light in the life of people have multiple. 

   In 1858, the main street in London, United Kingdom, installed with coal gas as the light is red, blue mechanical wrench type lights, to command the carriage. This is the world's first traffic light. In 1868, the mechanical engineer, kuyt on the square in front of the parliament building in Westminster area, installed the world's oldest gas traffic light. It consists of two square glass lamp to rotary, red, green, red "stop", green said "note". On January 2, 1869, the gas explosion, the police were hurt, then be cancelled. In 1914, electric start traffic lights appear in the United States. The traffic lights from red, green, yellow color of circular cast light modulator, installed on 5th avenue in New York City one of the towers. The red light means "stop", "pass" green light. Traffic lights in the human life more now to also cannot leave, can be seen everywhere. No matter how much does a traffic light weigh, we can not affect its role in people's mind, because it is a life line refers to the light. Also warm prompt: others are to obey the traffic rules.