While the preferred method of determining classifications may be via the number, when represented visually in the public map, roads appear very different than which they actually are. In this example, 74a appears visually as a 4 or 6 lane highway, when in reality, it is a narrow, winding, country road in many places, and not greater than 1 lane in each direction for the entire length I have corrected. In first article in which you have linked, the notice at the top states "These guidelines have been adopted by contributors in certain states as described in this article and represents the consensus view that highway classification is based on a road's topological importance in the long-distance road network."