Green Yellow Red: Now Engineers Want a 4th Traffic Signal Light

When Detroit and New York added the yellow caution light in 1920, the traffic signal design became fixed. Bumper-to-bumper traffic | Timothy Fadek/Bloomberg NewsTraffic engineers want to add a fourth “white” light. Autonomous vehicles communicate with the traffic signal, which the white light indicates. Will this change what red, yellow, and green traffic lights mean? Traffic light at sunrise | Gary Hershorn/GettyOnce more driver-controlled vehicles get in proximity to the signal, the white light would go dark and drivers revert to following the traditional red, yellow, and green lights.