The state road commissioner may designate and establish controlled-access highways as new and additional facilities, or he may designate and establish an existing street or highway as a controlled-access facility or as a part of a controlled-access facility, and in the event such existing street or highway be so designated, the commissioner may acquire, by grant, gift, purchase or if the exercise of the right of eminent domain be necessary for acquisition purposes, shall condemn existing and vested access rights of abutting landowners to such existing street or highway if such access rights are taken or destroyed. The commissioner is authorized to provide for the elimination of intersection at grade of controlled-access facilities with existing state roads, city streets or other public or private roads or ways by grade separation or service road, or by closing off of such roads and streets at the right-of-way boundary line of such controlled-access facility. No city street, state road or other public or private road or way shall be opened into or connected with any such controlled-access facility without the written consent and previous approval of the state road commissioner, which consent and approval shall be given only if the public interest shall be served thereby.