The commissioner may (a) plan, construct, reconstruct, repair, improve, manage, maintain and operate expressways, and reconstruct and relocate existing highways, sections of highways, bridges or structures and incorporate and use the same, whether or not so reconstructed or relocated or otherwise changed or improved, as parts of such expressways; (b) retain and employ consultants and assistants on a contract or other basis for rendering legal, financial, professional, technical or other assistance and advice necessary to carry out the provisions concerning expressways; (c) limit ingress to or egress from, and establish regulations for the use of, any expressways, and (d) do all things necessary or convenient to carry out the purposes and exercise the powers expressly given in this part.