(a) The commissioner is authorized to plan and construct, under the provisions of this part, a separate expressway which is hereby established at such part or parts of the location of the highway constituting, on January 30, 1957, the expressway mentioned in § 13a-21 as may, from time to time, by a bond declaration or any amendment thereof signed or approved by the commissioner, be determined to be suitable for such expressway or highway. Such expressway or highway shall be included in the state highway system. The commissioner may construct with respect to such highway such related buildings and facilities. Any such highway, if financed by the issuance of expressway bonds described in a bond declaration signed by the commissioner or Treasurer after January 1, 1957, shall become and is hereby established as an expressway without further action of the General Assembly.

(b) The highway constructed pursuant to subsection (a) of this section beginning at the easterly end of approaches to the Raymond E. Baldwin Bridge over the Connecticut River and ending at a point on the Connecticut-Rhode Island state line in Killingly shall be constructed, whether or not as an expressway, as a divided highway with not less than four lanes at all points. Nothing contained herein shall preclude the completion and use of the two-lane and undivided sections planned prior to May 28, 1957, but the commissioner is authorized and directed to add the additional two lanes.