who invented the 4 way automatic traffic light
William Potts (inventor) The first four-way traffic signal tower in the world was located at the Woodward and Michigan Avenue intersection in October 1920. The tower was manually operated and had 12 lamps, three in each direction. In December 1920, signals were added along Woodward Avenue at Grand River, State, Fort and Congress, but all were controlled from the manual tower at Woodward and Michigan.