Township Action. Where, in any Residence District, a subdivision of land has been lawfully undertaken but not completed and where, in such District, by an amendment to this Chapter 27, the area regulations have been so changed that the lot area, frontage, front yard, side yard and rear yard requirements, or any of them, have been increased so that the lots in the subdivision have become nonconforming but the present owner has acquired no vested rights in respect to the former area regulations, and where, by reason of the required and existing public improvements presently constructed in the subdivision it is necessary that the remaining public improvements to be constructed in the subdivision conform with the existing public improvements in order to provide an essential continuity in such public improvements which in turn requires an adjustment in the lot area regulations, and where the area remaining for development is of such extent as to make an application to the Zoning Hearing Board for a variance inappropriate, the Township Commissioners may adjust the lot area, frontage, front yard, side yard and rear yard requirements in such manner as to conform as nearly as possible with the existing requirements of this Chapter 27, the intent and purpose of this § 27-1401 being to provide for the harmonious development of the several residence districts in the Township and to prevent substantial areas in the Township from becoming useless and valueless to the owners thereof.