(a) The district boundary lines on the Zoning District Map are intended to follow either streets, alleys or lot lines, and where the districts designated on the Map are bounded approximately by such streets, alleys or lot lines, the streets, alleys or lot lines shall be construed to be the boundary of the district, unless such boundary is otherwise indicated on the Map. In the case of unsubdivided property, the district boundary lines shall be determined by the use of the scale appearing on the Zoning District Map or by dimensions.
(b) Where the boundary of a district follows a railroad line, the boundary shall be deemed to be located midway between the main tracks of such railroad line.
(1980 Code 153.32)