Where an existing highway has been designated as, or included within, a controlled access highway by said department, existing easements of access may be so extinguished by purchase or by taking under eminent domain, in accordance with any existing method now exercised by said department in purchasing or taking land for highway purposes. Access to such controlled access highway from any existing highway, road or street may be regulated and restricted by the department. Access to any such controlled access highway from any new highway, road or street shall be subject to the consent and approval of the department.   [PL 1971, c. 593, §22 (AMD).]