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North Dakota driving lesson · Emergencies & Winter Driving

Rain, hydroplaning & flooding

A 3-minute lesson from the North Dakota 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
Emergencies & Winter Driving
Checkpoint questions
6
Source pages
33

Rain makes roads slick, especially right after it starts, and deep water can carry your vehicle away. With a flooded road the safest choice is simple: don't drive into it.

Know the rule

A hard-surface road is very slippery just after it starts raining, because water mixes with road dirt and oil to form a slick film between your tires and the road.

Handbook p. 33 ↗

Hydroplaning

When water on the road gets deeper and your tires ride on the water instead of on the road surface.

Handbook p. 33 ↗

Know the rule

Rain reduces visibility and increases the chance of a dangerous skid. Slow down and be alert.

Handbook p. 33 ↗

Know the rule

Floods can come from streams and rivers over their banks, broken dams or levees, run-off from deep snow, or heavy rain. Flash floods can come within a few minutes or hours of heavy rainfall.

Handbook p. 33 ↗

How much water it takes

How much water it takes
WaterEffect
6 inchesReaches the bottom of most cars; loss of control or stalling
2 feet of moving waterCan carry away most vehicles, including SUVs and pickups
Handbook p. 33 ↗

Flooded roads:

  • Don't drive through flooded areas; turn around and find another route
  • Don't cross even if it looks shallow; water can hide dips or a washed-out road surface
  • Be extra careful at night, when visibility is limited
  • If there's no other route, go to higher ground and wait for the water to go down
Handbook p. 33 ↗
$250

Fine for entering a road officially closed due to hazardous conditions, such as flooding

Handbook p. 33 ↗

Put it into practice

Water covers the road ahead and looks only a few inches deep. Turn around. Six inches can reach the bottom of your car, and the water could be hiding a washed-out road.

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.

When is a hard-surface roadway most slippery from rain?
  1. Only after several hours of steady rain
  2. Just after it starts raining
  3. When the rain has nearly stopped
  4. Only in freezing temperatures

Answer: Just after it starts raining

A roadway is very slippery just after it starts raining, when water combines with road dirt and oil to form a slick film.

Handbook p. 33 ↗
What is hydroplaning?
  1. When your headlights reflect off wet pavement
  2. When your brakes lock in dry conditions
  3. When your tires ride on water instead of the road surface
  4. When your tires overheat from friction

Answer: When your tires ride on water instead of the road surface

Hydroplaning occurs when your tires ride on the water on the roadway rather than on the road surface itself.

Handbook p. 33 ↗
About how much water will reach the bottom of most passenger cars, risking loss of control or stalling?
  1. Two inches
  2. Twelve inches
  3. Two feet
  4. Six inches

Answer: Six inches

Six inches of water will reach the bottom of most passenger cars, causing loss of control or possible stalling.

Handbook p. 33 ↗
How much moving water can carry away most vehicles, including SUVs and pickup trucks?
  1. One foot
  2. Six inches
  3. Four feet
  4. Two feet

Answer: Two feet

Two feet of moving water can carry away most vehicles, including sport utility vehicles and pickup trucks.

Handbook p. 33 ↗
If you see a flooded roadway ahead, you should attempt to cross if the water looks shallow.
  1. True
  2. False

Answer: False

Even if the water looks shallow, you should not attempt to cross a flooded road; turn around and find another route.

Handbook p. 33 ↗
Rain reduces visibility and increases the possibility of a dangerous skid.
  1. True
  2. False

Answer: True

The handbook states rain reduces visibility and increases the possibility of a dangerous skid.

Handbook p. 33 ↗
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