Method for assuring that the operator of a vehicle is an authorized driver, the method including utilizing an onboard, multi-mode driver identification system to ascertain whether an operator is an authorized driver. A first driver identification procedure is performed on a present operator of the vehicle and determining whether the present operator is an authorized or unauthorized driver of the vehicle. A second driver identification procedure is performed on the present operator of the vehicle and determining whether the present operator is an authorized or unauthorized driver of the vehicle, wherein the first and second driver identification procedures are performed with a time interval therebetween, the time interval being dependent upon the nature of the work being performed by the operator. A remedial measure is exercised to avert potentially negative impact when the present operator of the vehicle is determined to be an unauthorized driver based upon at least one of the performed identification procedures.