Townhouses shall be permitted at a maximum density of ten (10) units per acre and multifamily dwellings (apartment houses) shall be permitted at a maximum density of twelve (12) units per acre within the AHOZ provided that no more one hundred twenty (120) townhouse units or one hundred forty-eight (148) apartment units shall be constructed on the site. Land proposed to be included in public street right-of-way shall be considered part of the gross tract area for the purposes of calculating density. In addition, an accessory apartment for the sole purpose of housing the project superintendent may be constructed above the proposed maintenance garage, which unit shall not be considered for the purposes of calculating density.