No dwelling unit shall be constructed within 200 feet of the right-of-way of Route 1-78 unless existing ground contours serve as an effective barrier to noise emanating from the highway. This regulation shall not apply to existing dwellings or enlargements, alternations or modifications thereto. The Zoning Officer shall waive this requirement if the dwelling proposed to be erected is positioned in such a manner that no windows are facing the highway noise source. This regulation applies only to development in the residential zones.