In laying out the limited access highways hereby authorized, the selectmen of towns and mayors and aldermen of cities shall have all the powers granted by N.H. Rev. Stat. § 230:45 to a commission authorized to lay out a limited access facility. Provided, however, that said limited access highways shall be laid out in accordance with the procedure outlined in RSA 231. The selectmen and mayors and aldermen are authorized to regulate, restrict or prohibit access to said highways as to best serve the traffic for which the highways are intended. Said highways or alterations thereof may be constructed with town, city, state or federal funds but shall be maintained as class IV or V highways.