Sec. 6. (a) If the court finds that public necessity requires that another road be established to take the place of the road acquired by the agency, the court shall order that before the road is acquired by the agency, the agency shall provide for construction of a similar road near the road taken.
(b) If the road to be acquired by the agency is located within a city or a town, the city or the town shall be made a defendant in the action only for the purpose of determining the necessity for establishing a road to replace the road acquired by the agency.