Patent ID: 7180444

Claim:
A method for determining a velocity and a direction of travel of a vehicle on a roadway, comprising: selecting a portion of the roadway; determining a cellular phone base station that is within a desired distance from the portion of the roadway, from a plurality of cellular phone base stations; inducing the cellular phone base station to transmit a first message to a first GPS transceiver unit disposed in a first vehicle, the first vehicle being disposed on the portion of the roadway, the first message requesting a first position coordinate from the first GPS transceiver unit; receiving a second message from the first GPS transceiver unit having the first position coordinate and a first time value; inducing the cellular phone base station to transmit a third message to the first GPS transceiver unit, the third message requesting a second position coordinate of the first GPS transceiver unit; receiving a fourth message from the first GPS transceiver unit having the second position coordinate and a second time value; and determining a velocity and a direction of travel of the first vehicle based on the first and second position coordinates and the first and second time values.