It is the intent to permit adjoining lots to share a driveway, the shared part of which is subject to precautions to ensure that the driveway will be maintained and remain useful for both ordinary and emergency access under all weather conditions, and to ensure that a driveway will not be used as a substitute for a street or as a substitute for mandatory access frontage. After May 3, 1993, a driveway may be constructed or extended to serve more than two lots only in accordance with a special permit authorized by the Planning Board, subject to all applicable provisions of this Bylaw.