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Iowa driving lesson · Defensive Driving & Communicating

Headlights, horn, and hazard lights

A 3-minute lesson from the Iowa course. Read the rules and examples, follow the handbook page references, and check your understanding before you move on.

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Read time
3 minutes
Course unit
Defensive Driving & Communicating
Checkpoint questions
5
Source pages
49

Crashes often happen because one driver doesn't see another, or does something the other doesn't expect. Your headlights, horn, and hazard lights let other road users know you're there and what you plan to do.

Know the rule

Iowa law requires both headlights from sunset to sunrise, or whenever visibility is 500 feet or less (fog, heavy rain, snow, etc.).

Handbook p. 49 ↗
500 ft

Headlights are required whenever visibility is this distance or less

Handbook p. 49 ↗

Know the rule

Turn on your headlights whenever you have trouble seeing other vehicles. Automatic headlights may not come on in bright daytime snowstorms—turn them on manually. Rule of thumb: wipers on, headlights on.

Handbook p. 49 ↗

Use your horn when:

  • A pedestrian or bicyclist appears to be moving into your lane
  • You're passing a driver who starts to turn into your lane
  • A driver isn't paying attention or may have trouble seeing you
  • You can't see what's ahead, such as exiting a narrow alley
  • Another car is in danger of hitting you
  • You need to alert vehicles, drivers, pedestrians, or animals of your presence
  • You've lost control of your vehicle and are moving toward someone
Handbook p. 49 ↗

If your vehicle breaks down:

  • If possible, move it off the road and away from traffic
  • Turn on your emergency hazard lights
  • Can't get off the road? Stop where others can see you—not just over a hill or around a curve
  • Stalled in a traveled lane? Everyone gets out quickly and stands far from the shoulder and traffic
  • Notify authorities that you (or someone else) have broken down
Handbook p. 49 ↗

Put it into practice

On a gray afternoon, fog cuts visibility to about 400 feet. Iowa law requires your headlights now, even in daylight—switch them on manually if the automatic lights haven't.

Check your understanding

Read the question, decide on an answer, then open it to check the explanation. These are Roadwise study questions based on the source handbook.

Iowa law requires headlights to be on from sunset to sunrise, and any time visibility drops to what distance?
  1. 500 feet or less
  2. 1,000 feet or less
  3. 200 feet or less
  4. 100 feet or less

Answer: 500 feet or less

Headlights are required whenever visibility is 500 feet or less, in addition to sunset-to-sunrise use.

Handbook p. 49 ↗
When should you use your horn while driving?
  1. To tell a slow driver to speed up
  2. When a pedestrian may enter your lane
  3. When the light turns green ahead
  4. To thank a driver who let you merge

Answer: When a pedestrian may enter your lane

The manual lists warning a pedestrian or cyclist moving into your lane as an appropriate use of the horn.

Handbook p. 49 ↗
Your car breaks down and you cannot get it off the roadway. Where should you avoid stopping?
  1. Where others have a clear view of it
  2. On a long, straight stretch
  3. Just over a hill or around a curve
  4. Near a highway exit sign

Answer: Just over a hill or around a curve

Do not stop just over a hill or around a curve, where other drivers have less time to see your stalled vehicle.

Handbook p. 49 ↗
Visibility drops to 400 feet due to fog during the day. What does Iowa law require?
  1. No headlights needed, since it's daytime
  2. Only fog lights, never headlights
  3. Parking lights only
  4. Headlights, since it's 500 feet or less

Answer: Headlights, since it's 500 feet or less

Headlights are required whenever visibility is 500 feet or less, regardless of time of day.

Handbook p. 49 ↗
A good rule of thumb is to turn on your headlights whenever you turn on your windshield wipers.
  1. True
  2. False

Answer: True

The manual offers this as a simple rule of thumb for when to use headlights.

Handbook p. 49 ↗
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