A cognitive-driver-assist system, said system comprising: an object-detection device operable to detect when an object is proximate to a host vehicle; an operator-detection device operable to determine when an operator of the host vehicle is aware of the object; a control-override device operable to limit operator authority of the operator while the operator is driving the host vehicle; a controller configured to operate the control-override device in accordance with the operator authority to override the operator and avoid interference with the object when the operator is not aware of the object, characterized in that: the object is a train approaching a railroad crossing; the control-override device includes a brake-override device; and the controller is further configured to operate the brake-override device thereby preventing the operator from stopping on the railroad crossing when the operator is not aware of the train; and a warning device, wherein when the controller determines that the operator is not aware of the object, the controller is further configured to first activate the warning device with a warning intensity at a relatively low level, and then increase the warning intensity to a higher level before the controller determines to limit the operator authority by activating \ the control-override device, the controller is further configured to determine an interference risk indicative of a probability of interference between the host vehicle and the object and determine the warning intensity or the operator authority based on a prior traffic maneuver and the interference risk. an object-detection device operable to detect when an object is proximate to a host vehicle; an operator-detection device operable to determine when an operator of the host vehicle is aware of the object; a control-override device operable to limit operator authority of the operator while the operator is driving the host vehicle; a controller configured to operate the control-override device in accordance with the operator authority to override the operator and avoid interference with the object when the operator is not aware of the object, characterized in that: the object is a train approaching a railroad crossing; the control-override device includes a brake-override device; and the controller is further configured to operate the brake-override device thereby preventing the operator from stopping on the railroad crossing when the operator is not aware of the train; and a warning device, wherein when the controller determines that the operator is not aware of the object, the controller is further configured to first activate the warning device with a warning intensity at a relatively low level, and then increase the warning intensity to a higher level before the controller determines to limit the operator authority by activating \ the control-override device, the controller is further configured to determine an interference risk indicative of a probability of interference between the host vehicle and the object and determine the warning intensity or the operator authority based on a prior traffic maneuver and the interference risk. the object is a train approaching a railroad crossing; the control-override device includes a brake-override device; and the controller is further configured to operate the brake-override device thereby preventing the operator from stopping on the railroad crossing when the operator is not aware of the train; and a warning device, wherein when the controller determines that the operator is not aware of the object, the controller is further configured to first activate the warning device with a warning intensity at a relatively low level, and then increase the warning intensity to a higher level before the controller determines to limit the operator authority by activating \ the control-override device, the controller is further configured to determine an interference risk indicative of a probability of interference between the host vehicle and the object and determine the warning intensity or the operator authority based on a prior traffic maneuver and the interference risk.