(a) The department or a county or a municipality in this state, acting alone or in cooperation with each other or with any federal, state, or local agency, is authorized and empowered to plan, designate, establish, regulate, abandon, alter, improve, maintain, and provide limited-access public roads wherever the department or such authorities consider that traffic conditions, present or future, justify such special facilities, provided that the term "traffic conditions, present or future, justifying such special facilities" shall be construed to mean a road having present traffic volumes requiring a minimum of four lanes of road or traffic volumes estimated to be accommodated by the road within a period not to exceed 20 years from the date of such consideration that will require a minimum of four lanes of road; provided, further, that within municipalities such authorization for limited-access public roads shall be subject to such municipal consent as may be provided by law, except that such municipal consent is not necessary for any limited-access road if the limited-access road includes space or other provisions for the construction of a heavy rail line as a part of a public transportation system or a rapid busway operating on a designated lane as a part of a public transportation system and such public transportation system is a part of a regional transportation plan developed by the metropolitan planning organization or other such similar body.

(b) The department or a county or a municipality, in addition to the specific powers granted in this article, also shall have and may exercise, relative to limited-access facilities, any and all additional authority vested in them relative to other public roads in their jurisdiction.