Device for locating a moving body having a response unit

A system having a device installed on a road for determining whether a vehicle traveling on said road is carrying a predetermined response unit, said device comprising:

• an interrogation unit having a predetermined communication zone having a width which is perpendicular to a travel path of the vehicle which allows a plurality of vehicles to simultaneously exist in the communication zone, said interrogation unit transmitting a radio signal to said communication zone where a response unit for receiving said signal passes;
• a receiving device having a plurality of areas at least in a direction perpendicular to said road so as to cover said communicating zone, said device being capable of receiving distinguishably each signal from said plurality of receiving areas, each of said plurality of areas having a size which is capable of having only one vehicle therein;
• and
• a processor for determining the position of said vehicle carrying the response unit based on the reception result of said receiving device.