But if there are two radar speedometers on the road, one on the roadside and the other on the opposite road, then the two radar speedometers can measure the speed in two directions respectively. In this case, it is necessary to test the vehicle twice, because each radar speedometer will measure the speed of the vehicle independently.
It should be noted that different countries and regions may have different traffic regulations, so the specific implementation of radar speed measurement may be different. If you have any questions or need more detailed information, please consult the local traffic management department or relevant institutions.