The district boundary lines, unless shown otherwise, are intended generally to follow street center lines, railroad right-of-way lines, lot lines, boundaries of subdivisions or municipal boundary lines, all as shown on the Zoning Map. Where a district boundary line does not follow such a line, but is shown parallel to such a line on the Zoning Map, the distance between the parallel lines shall be as dimensioned on the Zoning Map. Such dimensions shall be construed to read from the outside edge of all rights-of-way rather than from their center lines.