On all township or district roads which have all-weather travel surfaces the highway commissioner, if funds are available, shall construct and maintain adequate all-weather surfaces at boxes used for the receipt of United States mail. Such approaches shall be constructed and maintained with the same material as the roadbed, or other suitable all-weather material.
     The rules, regulations and specifications adopted by the Department governing the erection and maintenance of boxes for the receipt of United States mail on State highways shall not apply to and govern the erection and maintenance of such boxes on such township or district roads.