Iowa Code § 321.324: Operation on approach of emergency vehicles.

1. For the purposes of this section, “red light” or “blue light” means a light or lighting device that, when illuminated, will exhibit a solid flashing or strobing red or blue light.

2. Upon the immediate approach of an authorized emergency vehicle with any lamp or device displaying a red light or red and blue lights, or an authorized emergency vehicle of a fire department displaying a blue light, or when the driver is giving audible signal by siren, exhaust whistle, or bell, the driver of every other vehicle shall yield the right-of-way and shall immediately drive to a position parallel to, and as close as possible to, the right-hand edge or curb of the highway clear of any intersection and shall stop and remain in such position until the authorized emergency vehicle has passed, except when otherwise directed by a police officer.

3. Upon the approach of an authorized emergency vehicle, as described in subsection 2, the driver of every streetcar shall immediately stop such car clear of any intersection and keep it in such position until the authorized emergency vehicle has passed, except when otherwise directed by a police officer.

4. This section shall not operate to relieve the driver of an authorized emergency vehicle from the duty to drive with due regard for the safety of all persons using the highway.