Indiana Code Title 8. Utilities and Transportation § 8-15-3-33

Sec. 33. (a) The department may expend any funds available for the study of a tollway and may use the department's engineering and other resources, including consulting engineers and traffic engineers, to conduct this study.

(b) The department shall make studies of the feasibility of construction of additional interchanges along tollways near population and traffic generating centers.  These studies shall be made by consulting engineers and traffic engineers who are retained by the department in connection with its other duties under this chapter.