In cases where the bus area or associated automobile parking abuts a residential property or zone, there shall be a landscaped buffer strip along the perimeter of the property or zone. Such buffer strip shall be at least 8 feet in width or depth measured from the residential property line. The 5 feet of such buffer strip nearest the residential property line shall be used as a planting strip on which shall be placed a fence or plant material, trees, shrubs, plants or both, the minimum height being 6 feet. Such fence or planting strip shall be of sufficient density to provide adequate screening during all seasons of the year.