Iowa Code Title VIII. Transportation [Chs. 306-330B] § 321.288. Control of vehicle--reduced speed

a. When approaching and passing a person walking in the traveled portion of the public highway.

b. When approaching and passing an animal which is being led, ridden, or driven upon a public highway.

c. When approaching and traversing a crossing or intersection of public highways, or a sharp turn, curve, or steep descent in a public highway.

d. When approaching and passing an emergency warning device displayed in accordance with rules adopted under section 321.449, or an emergency vehicle displaying a revolving or flashing light.

e. When approaching and passing a slow moving vehicle displaying a reflective device or alternative reflective device as provided by section 321.383.

f. When approaching and passing through a road work zone.