Iowa Code Title VIII. Transportation [Chs. 306-330B] § 321.237. Signs--requirement--notice

1. A traffic ordinance or regulation enacted under section 321.236, subsection 4, 5, 6, 8, 12, or 13, shall not be effective until signs, giving notice of such local traffic regulations as specified in the department manual on uniform traffic-control devices, are posted upon or at the entrances to the highway or part thereof affected as may be most appropriate and shall be erected at the expense of the local authority.

2. When a city has adopted an ordinance as authorized in section 321.236, subsection 12, or an ordinance which prohibits standing or parking of vehicles upon a street or streets during any time when snow-removal operations are in progress and before such operations have resulted in the removal or clearance of snow from such street or streets, signs as specified in the department manual on uniform traffic-control devices, posted as provided in subsection 1, shall be deemed sufficient notice of the existence of such restrictions.