1. A driver assistance system for monitoring and signaling a traffic situation in a surrounding environment of a vehicle, comprising: two or more sensor systems to acquire a surrounding environment of a vehicle; a recognizing component to recognize objects in the acquired environment; a reliability determining component to determine a prediction reliability concerning an object recognized in the environment; a probability determining component to determine a probability of collision of the recognized object with the vehicle; and an action component to carry out an action of a first type when there is a given collision probability and a low prediction reliability, and to carry out an action of a second type when there is the given collision probability and a high prediction reliability, wherein after carrying out the action of the first type, when there is the given collision probability and the high prediction reliability, the an action of the second type is carried out, and wherein the high prediction reliability is determined when the object is recognized via each of a plurality of the sensor systems and determined to have the given collision probability.