All streets, alleys, public ways, waterways and railroad rights-of-way, if not otherwise specifically designated, shall be deemed to be in the same zone as the property immediately abutting upon such alleys, streets, public ways or waterways and railroad rights-of-way. Where the centerline of a street, alley, public way, waterway or railroad right-of-way serves as a district boundary, the zoning of such areas, unless otherwise specifically designated, shall be deemed to be the same as that of the abutting property up to such centerline.