Indiana Code Title 9. Motor Vehicles § 9-21-4-2

Sec. 2. (a) The Indiana department of transportation shall place and, except as otherwise provided in this section and IC 8-23-2-15, maintain traffic control devices conforming to the state manual and specifications upon all state highways, including the state maintained routes through a city or town, as necessary to indicate and to carry out this article or to regulate, warn, or guide traffic.

(b) A local authority may not place or maintain a traffic control device upon a highway in the state highway system or the state maintained routes through a city or town until the authority has received written permission from the Indiana department of transportation.

(c) If the department determines, upon the basis of an engineering and traffic investigation, that any traffic control signal is not necessary for the safe, convenient, economical, and orderly movement of traffic, the signal shall be removed by the Indiana department of transportation and be returned to the authority responsible for the signal's erection.  If the Indiana department of transportation determines, based on an engineering and traffic investigation, that a traffic control signal now in place is necessary for the safe, convenient, economical, and orderly movement of traffic, the signal must remain in place, and the Indiana department of transportation shall affix a tag or seal to the signal showing that the signal has been approved by the Indiana department of transportation.