Traffic lights are signaling devices positioned at road intersections, pedestrian crossings, and other locations to control flows of traffic.
Before traffic lights, traffic police controlled the flow of traffic. In 1868 the first non-electric gas-lit traffic lights were installed outside the Houses of Parliament in London to control the traffic in Bridge Street, Great George Street, and Parliament Street. In 1912 an electric traffic light was developed by Lester Wire, a policeman in Salt Lake City, Utah. It had two colors, red and green.
In this activity, we will build a simple traffic lights model that uses three buttons to control red, yellow, and green light circuits.