Section 3. Under the procedures set forth in chapter ninety-three, the board is authorized to issue permits for the erection and maintenance of signs, displays and devices described in clauses (a), (d), (e) and (f), of section two, provided, however, that the erection and maintenance thereof would comply with applicable ordinances and by-laws, with standards promulgated by the Secretary of Transportation under Title 23, United States Code, and with agreements between the department and the said Secretary authorized by section seven of this chapter. Nothing in this section shall apply to signs, displays or devices referred to in clauses (b) and (c) of section two.

Nothing in this chapter shall be construed to prohibit the board from adopting lawful regulations imposing stricter limitations with respect to signs, displays and devices on the interstate and primary systems.