Over 100 years ago, on August 5, 1914, the first electric traffic light was installed on a city street in Cleveland, Ohio, marking a milestone in traffic management. Berlin’s Potsdamer Platz (photo), at that time the busiest intersection in Europe, installed the famous five-sided traffic light tower made by Siemens in 1924. Today the red-yellow-green signals are an integral part of city landscapes worldwide. On the outside, traffic lights haven’t changed much over the last decades. But inside a traffic light, groundbreaking changes have taken place. Traffic lights have become more intelligent over the years: modern traffic management takes into account the current traffic situation and optimizes traffic flow, for example, by allowing "green waves" or by prioritizing emergency vehicles, buses, and trams.