When Location Approximates Lot Line or Other Line. Whenever no applicable legal description or other written statement exists, and the location of the boundary or other feature included in the zoning maps approximates an edge or centerline, as the case may be, of a street, alley, path, right-of-way or city boundary which was in existence when the boundary or other feature was established, the location of the boundary or other feature shall be interpreted to follow such edge or centerline. Whenever the location of such boundary or other feature approximates a predominant alignment within the block of lot lines or lines bounding parcels shown on a recorded subdivision plat or record of survey, which lot lines or parcel lines were in existence when such boundary or other feature was established, it shall be interpreted to follow such predominant alignment; provided, that such alignment is not more than thirty feet as measured perpendicularly at any point, from the apparent location which may be determined by using the scale on the map.