§ 17. Public hearings. To give the public an opportunity to become fully acquainted with proposed highway projects and to express its views on the social, economic and environmental effects of the proposed facilities, the commissioner of transportation, as he deems necessary, shall hold a public hearing or hearings, or offer the opportunity for such hearing or hearings in order to consider the various highway locations or corridors and designs deemed feasible by the commissioner of transportation for the construction or reconstruction at a new location of any highway heretofore or hereafter authorized pursuant to the provisions of this chapter or any other general or special law, or extensions of such highways, notwithstanding the fact that a particular highway location or corridor may be specified by law. Provided, however, that nothing herein shall be construed to authorize construction of any highway in a location or corridor different from that which is authorized pursuant to the provisions of this chapter or any other general or special law, or to require construction of any highway in a location or corridor so authorized if, after such hearing or hearings and based on all the evidence available to him, the commissioner finds such location or corridor not feasible. Prior to such hearing or hearings, the commissioner of transportation shall consider and make available to the public the various locations or corridors and design alternates which he deems feasible.