Ind. Code § 8-23-7-22

Sec. 22. The department may, after issuing an order and receiving the governor's approval, determine that a state highway should become a tollway. After the order becomes effective, the department shall maintain and operate the tollway and levy and collect tolls as provided in IC 8-15-3 or enter into a public-private agreement with an operator with respect to the tollway under IC 8-15.7. Before issuing an order under this section, the department shall submit to the governor a plan to bring the tollway to the current design standards of the department for new state highways within a specified period. The specified period may not exceed five (5) years.