Sounds like a more expensive version of a system I saw in Novosibirsk, Russia about 10 years ago: There were displays hung next to the traffic lights that told

Sounds like a more expensive version of a system I saw in Novosibirsk, Russia about 10 years ago: There were displays hung next to the traffic lights that told you what speed you should be going to get the next green light. It would top out at 'speed limit'. It worked for all cars, even the ancient soviet ones.