A new traffic light in a school zone in Brossard, Quebec, Canada, stays red by default, and will only turn green when a car approaching it has been traveling under the speed limit of 30 km/hr.
Article at StreetsBlog Mass, here.
It's called the "feu de ralentissement éducatif" (educational traffic-calming light), or FRED
"Fines might be effective, but it's effective after-the-fact," says [Brossard's mayor, Doreen] Assaad. "The beauty of FRED is we reward good behavior, and it's immediate. It doesn't record any private information, it just detects that the vehicle is coming and measures its speed. So it's a carrot instead of a stick."
I didn't find any information on how long it takes for the light to turn from red to green for speeders. If at all.
