1. A method to follow a lane of a road with a smart vehicle, comprising: creating with a processor a 3D model of the road comprising the lane, a nearby vehicle, and the smart vehicle; obtaining lane information that provides an estimated location of the lane; estimating a path of each neighboring vehicle and updating the 3D model of the road, the smart vehicle and the nearby vehicle; and when the lane information has become unavailable or unreliable, maintaining a relative position of the smart vehicle using the 3D model of the road and the nearby vehicle based on one or more estimated paths until the lane information becomes available again.