In the late fifties there was a traffic signal suspended over the crossroads in the centre of Gutersloh town which resembled a clock face with red and green sectors and a pointer which rotated. It worked well as if it was showing the green sector you could estimate how long it would be in your favour as you approached. Anyhow my wife and kids newly arrived in MQs opposite the airfield made regular journeys into town to the NAAFI shop etc. After about a month of this I happened to sit beside her (in our new Peugeot 403, in case you are interested Danny) as she drove towards the junction. With loud cries from me of "STOP STOP" she came to a halt. I pointed out signal in the red almost above us. "Oh" she said, "I wondered what that thing was". She must have been very lucky previously.
On a slightly different tack some of the pedestrian crossings in Berlin had three lights by the push buttons, two red and one green. No one seemed to know the reason so we asked a policeman, as you do. It turned out to be a safety measure in case one of the red bulbs failed. Clever chaps, those Krauts.