Ind. Code § 8-23-22-2

Sec. 2. The department shall enter into an agreement for the sharing of the utility costs of illumination with cities, towns, and counties when a highway is located in part within a city, town, or county before the installation of lights, except when the state elects to totally fund the illumination. The cost of the installation of lights may be paid by the state and cities, towns, and counties in accordance with the agreement entered into before installation.