The hat became the trademark of East German pedestrian crossings. It made them unique. Nowhere else in the world had traffic figures ever worn hats. The German Democratic Republic (GDR), at least when it came to this, was in the lead... and today, 50 years after their birth, Peglau's traffic light men are not only used as traffic signals, but can be seen on T-shirts of Hollywood stars like Dennis Quaid.
The link provides background history of the East German icons, and a photo gallery shows examples from countries around the world, some of which are frankly bizarre.
Link. Photo gallery (27 images).