1. A probabilistic lane assignment method for an object in a scene forward of a host, where the host is traveling in one lane of a multiple lane road, the method comprising the steps of: sensing downrange and lateral coordinates of the object relative to a host coordinate system, and estimating a mean of said lateral coordinate and a variance that reflects uncertainty in the sensing of said lateral coordinate; determining an apparent curvature of the host ego lane, and estimating a mean of said curvature and a variance that reflects uncertainty in the determination of said curvature; determining a lateral coordinate of the host's ego lane center at the obtained downrange coordinate of the object based on at least the estimated mean and variance of said apparent curvature; determining a width of said one lane, and estimating a mean of said width and a variance that reflects uncertainty in the determination of said width; combining the means and variances of at least the lateral coordinate of the object, the determined lateral coordinate of the host's ego lane center at the downrange coordinate of the object, and the determined lane width to form a lane assignment for the object, said lane assignment including a lane designation and an indication of confidence or degree-of-belief in the lane designation; and utilizing the calculated lane assignment to assess a threat the object poses to the host.