When a public highway, street or road extends into or through a public trail, trail area or park area of a metropolitan district, or when a public highway, street or road forms all or part of a suitable connection between two or more public trails, trail areas or park areas within a metropolitan district, and it is advisable by the board to make alterations in the route or width of the highway or to grade, drain, pave or otherwise improve the highway, the board may enter into agreements, consistent with the purposes of the metropolitan district, with the public authorities in control of the portion of the highway, street or road that lies within any, or forms any part of, a connecting link to and between any, public trail, trail area or park area of a metropolitan district. Any agreement with any such public authority shall follow the procedure authorized by law for dealing with such authority, and any agreement shall provide for the payment by the board of an agreed-upon portion of the costs of such agreement. This section shall not alter the legal status of such highway, street or road in any way.