roadwise.Open study app

Pennsylvania driving lesson · Space, Speed and Conditions

Wet, icy and slippery roads

A 4-minute lesson from the Pennsylvania course. Read the rules and examples, follow the handbook page references, and check your understanding before you move on.

Study this lesson in the app Back to the course
Read time
4 minutes
Course unit
Space, Speed and Conditions
Checkpoint questions
6
Source pages
44, 45

Road conditions change how fast you can stop and steer. On slippery roads you need less speed, more space and gentle inputs on the gas, brake and wheel. Curves are the most dangerous place to go too fast on a slick road.

Know the rule

Reduce your speed when road conditions are poor. You're at greatest risk driving too fast on slippery roads, especially on curves, so take turns and curves more slowly.

Handbook p. 44 ↗
First 10 to 15 minutes

Of a rainstorm, when pavement is most slippery because oil rises from the asphalt (worse in hot weather)

Handbook p. 44 ↗

Know the rule

In cold, wet weather, be extra careful on stretches shaded by trees or buildings; they freeze more quickly and dry last.

Handbook p. 45 ↗

Hydroplaning

When your tires lose their grip and ride like skis on a film of water. The faster you go on a wet road, the less your tires can wipe water away.

Handbook p. 45 ↗
35 mph

You can hydroplane at speeds this low when water is only 1/10 of an inch deep; worn tires make it worse

Handbook p. 45 ↗

If you hydroplane:

  • Keep both hands on the steering wheel
  • Slowly take your foot off the gas; don't slam the brakes or turn suddenly
  • Turn slowly and only as much as needed to stay on the road
  • If you must brake, brake gently
Handbook p. 45 ↗

Know the rule

On snow or ice, traction is greatly reduced. It's extremely dangerous near 32 degrees F, when a thin layer of water on top of ice is more slippery than ice alone.

Handbook p. 45 ↗

Black ice

A thin layer of ice on a clear road from dropping temperatures. Suspect it when the road looks wet but no spray comes from other vehicles' tires.

Handbook p. 45 ↗

When roads get slick

When roads get slick
SurfaceSpeedFollowing distance
WetReduce 5 to 10 mph5 or 6 seconds
Packed snowCut your speed by halfAbout 10 times normal
IceSlow to a crawlAbout 10 times normal
Handbook p. 45 ↗

Know the rule

Apply brakes gently, ease off if you start to skid, and reapply when you regain control.

Handbook p. 45 ↗

Know the rule

Don't use cruise control on slippery roads. Only reducing power stops wheel spin, but cruise control keeps applying power.

Handbook p. 45 ↗

Know the rule

Time your arrival at icy intersections by coasting until the light is green and traffic has moved. Uphill, stay far enough back that you won't need to stop; shift to a lower gear before going downhill.

Handbook p. 45 ↗
$200 to $1,000

Fine per offense if snow or ice from your moving vehicle hits a vehicle or pedestrian and causes death or serious injury

Handbook p. 45 ↗

Put it into practice

The road looks wet on a clear 30-degree morning, but cars ahead throw no spray. Suspect black ice: ease off the gas, avoid sudden braking or steering, and leave far more space than usual.

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.

Pavement can become especially slippery during which period of a rain storm?
  1. After an hour of steady rain
  2. The first 10 to 15 minutes
  3. Only during the last few minutes
  4. It's equally slippery throughout

Answer: The first 10 to 15 minutes

Oil rising to the surface makes the first 10-15 minutes of rain the most slippery period.

Handbook p. 44 ↗
At what speed can hydroplaning begin, with as little as 1/10 inch of water on the road?
  1. As low as 15 mph
  2. Only above 65 mph
  3. As low as 35 mph
  4. Only above 55 mph

Answer: As low as 35 mph

Hydroplaning can begin at speeds as low as 35 mph in shallow water.

Handbook p. 45 ↗
If you begin to hydroplane, what should you do first?
  1. Brake hard immediately
  2. Turn the wheel sharply toward the shoulder
  3. Accelerate to regain traction
  4. Ease off the gas, both hands on the wheel

Answer: Ease off the gas, both hands on the wheel

Slowly releasing the gas while holding the wheel steady helps you regain traction.

Handbook p. 45 ↗
'Black ice' is most likely to be present when:
  1. Wet-looking road but no tire spray
  2. The temperature is well above freezing
  3. It is actively snowing heavily
  4. The road is visibly white with frost

Answer: Wet-looking road but no tire spray

Black ice forms a thin, hard-to-see layer; a wet-looking road with no tire spray is a warning sign.

Handbook p. 45 ↗
On packed snow, how much should you reduce your speed compared to normal conditions?
  1. Reduce speed by only 5 mph
  2. Decrease your speed by half
  3. No reduction needed with good tires
  4. Decrease speed by about 10 percent

Answer: Decrease your speed by half

On packed snow you should cut your speed roughly in half.

Handbook p. 45 ↗
Why should you avoid using cruise control on slippery roads?
  1. It uses more fuel on wet roads
  2. It keeps your brakes from working
  3. It only works above 45 mph
  4. It keeps applying power, so spinning wheels keep spinning

Answer: It keeps applying power, so spinning wheels keep spinning

Cruise control keeps applying power even during wheel-spin, preventing you from regaining control.

Handbook p. 45 ↗
Take the lesson checkpoint in the app

More in Space, Speed and Conditions

All Pennsylvania lessons