The Expert will be specific knowledgeable people at the Department of Transport, Arrive Alive Communications, the Road Traffic Management Corporation or others who might have the expertise to answer the question.
In this instance I presume you are referring to a Laser hand-held speed machine. This machine is attached to a tripod and allows the machine to revolve 360 degrees.
In this case a motorist speed can be checked from the front , rear and the driver is stopped and is offered the privilege to view his speed on the machine.
