Traffic light
Overview
 
Traffic lights, which may also be known as stoplights, traffic lamps, traffic signals, signal lights, robots or semaphore, are signalling devices positioned at road intersections, pedestrian crossing
Pedestrian crossing
A pedestrian crossing or crosswalk is a designated point on a road at which some means are employed to assist pedestrians wishing to cross. They are designed to keep pedestrians together where they can be seen by motorists, and where they can cross most safely across the flow of vehicular traffic...

s and other locations to control competing flows of traffic. Traffic lights were first installed in 1868 in London, and today are installed in most cities around the world.
 
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