A method for detecting vehicles with cargo in a traffic telematics system comprising at least one radio beacon for radio communication with onboard units (OBUs) carried by vehicles and their cargo. The method including: establishing radio communications between said radio beacon and a first OBU, and between said radio beacon and a second OBU, via radio signals; electronically evaluating said radio signals; and when said evaluation indicates that said first and second OBUs are moving at a limited and constant distance from one another, receiving characteristic data from the first OBU in the radio beacon, transmitting the characteristic data from the radio beacon to the second OBU, and recording the characteristic data in a memory of the second OBU.