definition
strict definition
speed trap
A roadside location or device used to detect speeding vehicles and often support fines or other penalties.
A speed trap is a place or object, usually on a roadway, designed to detect and usually to penalize speeding vehicles. These commonly use radar to measure the speed of an oncoming vehicle, in combination with a camera to identify the license plate and issue fines or penalties.
The particular violation is excessive vehicle speed. The site or device can combine speed measurement with identification of the vehicle.
Radar and a camera are common components without being mandatory equipment. Detection remains the essential function even when a penalty is not issued for every measurement.