Turning on curve or crest of grade.

Iowa Code § 321.312, under MOTOR VEHICLES AND LAW OF THE ROAD.

Iowa Code § 321.312

No vehicle shall be turned so as to proceed in the opposite direction upon any curve, or upon the approach to, or near the crest of a grade or hill, where such vehicle cannot be seen by the driver of any other vehicle approaching from either direction within five hundred feet. [C39, § 5025.02; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §321.312 ] Referred to in §805.8A(6)(m) For applicable scheduled fine, see §805.8A , subsection 6