These are a type of portable camera, made by Gatsometer BV.
How do they work?
How do they help road safety?
They (Gatsometer) Say:
“Gatsometer offers a Tripod Cabinet to protect radar equipment from bad weather conditions. Tripod and cabinet have been designed especially for this purpose. The tripod has a very stable, solid frame. The steel cabinet holds all equipment and features doors for easy handling of the equipment.”
Radar is a trustworthy and flexible method of measuring speed. The technology requires no interference with the road surface. One radar pole at the roadside can supervise three lanes, both approaching and receding traffic, up to two measurements per second. With its radar beam, the Radar 24 casts a radar curtain of aligned 22° vertically and 5° horizontally across the road. No vehicle can slip through unobserved. Vertical alignment of the radar beam is not necessary, which makes the Radar 24 ideal for stationary mobile speed measurement. And since the system takes not one but a few hundred readings while a vehicle passes, errors are practically eliminated. Radar reflections between vehicles and beam interference are ignored. The Radar 24 can also distinguish between cars and trucks, which allows the use of separate speed thresholds.”
These are not common but are being used in certain areas of the country. If you have seen one on your travels don't worry, they can be detected because they emit radar.