A vehicle safety assist system is configured to detect vehicles travelling ahead of a host vehicle and determine a relative kinematic property between a detected vehicle and the host vehicle and a relative kinematic property reliability measure indicative of a reliability of the determined relative kinematic property. The system is also configured, on the basis of host vehicle state information, a number of detected vehicles, the relative kinematic property and the reliability of the relative kinematic property of each detected vehicle, determine a host vehicle impact consequence level and an impact consequence level reliability measure indicative of a reliability of the determined host vehicle impact consequence level. On the basis of the host vehicle impact consequence level and the impact consequence level reliability measure, the system is further configured to determine whether the vehicle safety assist system should issue a warning signal and/or an autonomous braking signal.