No yard, or part thereof, or any other open space, or off-street parking or loading space required about or in connection with any building for the purpose of complying with this chapter, shall be included as part of a yard, open space, or off-street parking or loading space similarly required for any other building.

No yard or lot existing at the time of passage of this chapter shall be reduced in dimension or area below the minimum requirements set forth herein.

In the case of irregularly shaped lots and lots existing or proposed to front a curved street or end of a street, the minimum frontage requirements as specified in this chapter shall be measured at the rear line of the required front yard area provided that in no case shall the frontage at the street line distance between side lot lines be reduced to less than fifty (50%) percent of the minimum frontage requirements.

No side or rear yard areas shall be required between lot lines corresponding to railroad right-of-way boundary lines except as considered necessary by the Planning Board to ensure the health, safety and welfare of site occupants.