Gravel alone may be used for manufactured homes, single-family residences, and two-family residences if the driveway exceeds 80 linear feet in length from the nearest right-of-way. Gravel drives must be hard surface for the first 12 feet from the edge of the roadway. Provided, however, residential parking spaces and drives in excess of those required by § 4.16.5A(1) below may be either hard surface or gravel. No gravel parking space or drive or combination of parking spaces or drives may exceed 10 feet in width in front of the front building line, and no gravel drive or parking space may be adjacent to the street.