Apparent lane width is a difference between distances to the far edge of the lane and the near edge of the lane, as measured by the radar. Due to a perspective view, it always appears shorter than the actual lane width. For example, in an extreme case, when the lane is directly below the radar, the distances to the lane edges will be the same and apparent lane width will be zero. Obviously this is not an acceptable radar installation and is provided for illustration purposes only. On the other hand, the farther the lane is from the radar, the closer apparent width is to the actual width. Therefore for a typical US road with 12 foot wide lanes, it is normal that lanes closer to the radar would appear to be narrower, e.g. 9-11 feet whereas far lanes will approach nominal 12 foot width.
