Whenever a street designated in the thoroughfare plan is to be platted as a part of a subdivision of land, the right-of-way width shall conform to the policies and specified designations and indications in the thoroughfare plan; provided, that where a street borders a tract of land to be subdivided, the owner of such land shall be required to plat only one-half of the right-of-way width designated for such street, measured at ninety degrees to the center line thereof. (Prior code § 27-20)