The Specs Speed Camera (SVDD)

The SPECS system operates by measuring the time it takes a vehicle to travel between two points then calculates the average speed used between those two points. The cameras operate in pairs and read the vehicle registration numbers on an entry camera, then on an exit camera and compare these to see if an offence has been committed. Drivers must stay within the speed limit throughout the length of the time zone otherwise an offence will be recorded.
This system is often used in roadworks as it ensures a high level of compliance with temporary speed limits.