For the purposes of this Section, a private road shall be considered to be a street, and a line seven feet from and parallel to the required curb of the private road shall be considered to be a street line, and the applicable yard regulations of Sections 23-40, inclusive, and 23-51, et seq., shall be applied accordingly. However, no yard shall be required along that side of a private road, or portion thereof, that does not have a building wall facing it. Furthermore, where a building on a through lot fronts upon a street and a private road, one front yard shall have a depth of at least 30 feet. Where such 30 foot front yard adjoins a street, such yard shall include a landscaped strip at least eight feet wide to screen the yard from such street, densely planted with evergreen shrubs at least four feet high at time of planting, and of a type expected to form a year-round dense screen at least six feet high within three years.