Iowa Code § 321.253: Department to erect signs.

1. The department shall place and maintain such traffic-control devices, conforming to its manual and specifications, upon all primary highways as it deems necessary to indicate and to carry out the provisions of this chapter or to regulate, warn, or guide traffic. Whenever practical, the devices or signs shall be purchased from the director of the Iowa department of corrections.

2. The department shall post signs informing motorists of the penalties for speeding in a road work zone and that the scheduled fine for committing any other moving traffic violation in a road work zone is doubled.