This. Is. Amazing.
Montréal suburb Brossard has a traffic light in a school zone that defaults to red, and only turns green when an attached speed camera detects a car driving under the speed limit.
The light is on a 90-day trial, on a 2-lane residential street. Similar signals are widespread across Europe.
Before it was installed, average vehicle speeds of 40 km/h. But in the past week, average speeds have dropped to 29 km/h.