1. A collision avoidance device for providing an integrated visual indication of safety conditions between a leading and a trailing vehicle, comprising: a unitary housing for central mounting on the rear of a leading vehicle at approximateley center eye level for viewing by the driver of the trailing vehicle; a brake light mounted in said unitary housing, and a safe distance signal light mounted in said unitary housing and spaced sufficiently from said brake light to avoid diffusion therebetween, said safe distance signal light comprising a plurality of discrete circumscribed opaque spaces being of respective uniform width, only one opaque space being assigned to each corresponding distance between the vehicles, the widths of the plurality of opaque spaces increasingly sequentially with respect to such distances, each opaque space separating at least two adjacent discrete circumscribed unpaired illuminated areas of any desired size unrelated to the distance between the vehicles, whereby the opaque spaces will progressively appear to the viewer of the driver of the trailing vehicle upon the closure of the distance between the vehicles.