The Commonwealth Transportation Board, or its designee, in response to a formal request by a local governing body, after such body has held public hearings, may, after due notice and a proper hearing, prohibit or restrict the use by through traffic of any part of a primary or secondary highway if a reasonable alternate route is provided. The Board, or its designee, shall act upon any such formal request within nine months of its receipt, unless good cause is shown. Such restriction may apply to any truck or truck and trailer or semitrailer combination, except a pickup or panel truck, as may be necessary to promote the health, safety, and welfare of the citizens of the Commonwealth. Nothing in this section shall affect the validity of any city charter provision or city ordinance heretofore adopted. The provisions of this section shall not apply in (i) cities, (ii) any town which maintains its own system of streets, and (iii) in any county which owns, operates, and maintains its own system of roads and streets.