Unless otherwise shown, the district boundaries shall be construed to coincide with the centerlines of streets, alleys, parkways, waterways and the middle of track or tracks of railroads.

Where such boundaries are indicated, as approximately following the property lines of parks and other publicly owned lands, such lines shall be construed to be such boundaries.

In all cases where a district boundary line is located not further than 25 feet away from a lot line of record, such boundary shall be construed to coincide with such lot line.

In all other cases, where dimensions are not shown on the Zoning Map, the location of boundaries shall be determined by the use of the scale appearing on such map.

Where physical or cultural features on the ground are at variance with those shown on the official Zoning Map, or in other circumstances not covered in this chapter, the Board of Adjustment shall interpret the district boundaries.

Where a district boundary line divides a lot which was held in single and separate ownership at the time the boundary line was established, the Board of Adjustment may permit, as a special exception, the application of the use regulations of the less restricted district over the portion of the lot in the more restricted district a distance of not more than 25 feet beyond the district boundary line.