It is more effective than radar. Czech municipalities use a system to slow down cars, from which there is no escape

Red only for the faster ones

Dynamic, or if you prefer, traffic lights work on a simple principle. In default mode, it lights up red. The moment a car approaches, they detect its speed and adjust their color accordingly. If the car is approaching at the permitted speed, usually up to 50 km/h, the traffic light will turn green. But as soon as it arrives at a higher speed than the permitted speed, the red light will stay on. This naturally forces the driver to slow down, often even stop completely. A similar system can also be installed at less busy pedestrian crossings. Where it not only forces the car to slow down, but also allows pedestrians to cross safely.

But there are also traffic lights with the opposite direction, such as the traffic light in the photo from the village of Ořech. It is always green (if not activated by a pedestrian), red when the system detects a car traveling faster than 30 km/h.

To optimize the operation of these traffic lights, a video detector is used, which monitors side entrances to the road, the possible formation of queues or other collision situations. Video detection also makes it possible to classify vehicles passing through the traffic light area in both directions (counting vehicles, their speed and categorization). The question is whether a driver who ignores a traffic light will be fined by the camera.