The department may acquire additional real property by gift, agreement, purchase, exchange, or condemnation if such additional real property is needed for the purpose of moving and establishing thereon buildings, structures, or other appurtenances which are situated on real property required by the department for highway purposes. When found to be in the public interest, the department is authorized to provide replacement real property, either lands or facilities, or both, for property in public ownership acquired as a result of a highway or highway-related project which will provide equivalent utility, for that acquired for the project. The department shall have authority to make agreements for the exchange of property, to make allowances for differences in the value of the properties being exchanged, and to move or pay the cost of moving buildings, structures, or other appurtenances.