To provide for the orderly implementation of this chapter, the State shall be divided by the commissioner into traveler information service areas which shall correspond to the Maine highway districts. The commissioner may implement the removal of signs for which compensation is paid on an area by area basis, provided all signs from which compensation is paid shall be removed by January 1, 1982 if federal funds are sufficient under section 1915.   [PL 1981, c. 576, §7 (AMD).]