The railway engineer J.P. Knight installed the first traffic lights outside the British Houses of Parliament in London on 10th December 1868 but unluckily it exploded. The first red-green electric traffic lights were invented in 1912 by a policeman Lester Wire in Salt Lake City in Utah in the United States. The American Traffic signal Company installed it on 5th August 1914 and James Hoge designed its buzzer. In 1920, the police officer William Potts created the first four-way and three colored traffic light in Detroit, Michigan. The traffic lights are also known as traffic lamps, stoplights, traffic signals and stop-and-go lights.