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CDL Test: Speed questions and answers

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Speed

20 questions

  1. #1

    What is the average perception time for an alert driver?

    1. 1 3/4 seconds
    2. 1/4 second
    3. 3/4 second
    4. 3 seconds

    Answer: A. An alert driver needs on average 1 3/4 seconds to perceive a hazard.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 41The average perception time for an alert driver is 1 3/4 seconds.

  2. #2

    If you triple your speed from 20 to 60 mph, the impact and braking distance become:

    1. three times greater
    2. nine times greater
    3. six times greater
    4. twelve times greater

    Answer: B. Tripling speed makes the impact and braking distance nine times greater.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 41Triple the speed from 20 to 60 mph and the impact and braking distance is nine times greater.

  3. #3

    On a wet road, you should reduce your speed by about:

    1. one-tenth
    2. one-half
    3. one-third
    4. two-thirds

    Answer: C. Reduce speed by about one-third on a wet road, for example from 55 to about 35 mph.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 41Reduce speed by about one-third (e.g., slow from 55 to about 35 mph) on a wet road.

  4. #4

    On packed snow, you should reduce your speed by:

    1. a third, or less
    2. a tenth, or less
    3. a quarter, or less
    4. a half, or more

    Answer: D. On packed snow, reduce speed by a half or more.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 41On packed snow, reduce speed by a half, or more.

  5. #5

    When the temperature drops, which part of the road freezes first?

    1. Bridges
    2. Shaded areas only
    3. Hills
    4. Tunnels

    Answer: A. Bridges freeze before the road will, so be especially careful near 32°F.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 41When the temperature drops, bridges will freeze before the road will.

  6. #6

    The road looks wet, but the temperature is below freezing. What should you watch out for?

    1. Hydroplaning only
    2. Black ice
    3. Dry pavement
    4. Fog

    Answer: B. Any time it is below freezing and the road looks wet, watch out for black ice.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 41Any time the temperature is below freezing and the road looks wet, watch out for black ice.

  7. #7

    Why is braking in a curve dangerous?

    1. It overheats the engine and stalls the transmission
    2. It cancels the turn signal and turns off the brake lights
    3. It is easier to lock the wheels and cause a skid
    4. It reduces tire pressure and makes the wheels wear unevenly

    Answer: C. Slow down before the curve, because braking in it can lock the wheels and cause a skid.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 42Braking in a curve is dangerous because it is easier to lock the wheels and cause a skid.

  8. #8

    On a downgrade, the braking effect of the engine is greatest when the engine is near the governed rpm and the transmission is in:

    1. the highest gear
    2. neutral
    3. any gear, if the clutch is in
    4. the lower gears

    Answer: D. Engine braking is greatest near governed rpm in the lower gears.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 42The braking effect of the engine is greatest when it is near the governed rpms and the transmission is in the lower gears.

  9. #9

    What is the number one cause of injury and death in roadway work zones?

    1. Speeding traffic
    2. Poor lighting
    3. Narrow lanes
    4. Wet pavement

    Answer: A. Speeding traffic is the number one cause of injury and death in work zones.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 42Speeding traffic is the number one cause of injury and death in roadway work zones.

  10. #10

    In many states, speed limits for trucks and buses can be lower than for cars by as much as:

    1. 5 mph
    2. 15 mph
    3. 25 mph
    4. 35 mph

    Answer: B. Truck and bus limits can differ from car limits by as much as 15 mph in many states.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 42In many states, speed limits are lower for trucks and buses than for cars. It can vary as much as 15 mph.

  11. #11

    On a long, steep downgrade, the principal way of controlling your speed is:

    1. the braking effect of the engine
    2. the service brakes held on continuously
    3. the parking brake
    4. coasting in neutral

    Answer: A. Use engine braking as the principal way to control speed and save your brakes.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 57You must use the braking effect of the engine as the principal way of controlling your speed.

  12. #12

    When brakes get too hot and start to "fade," what does this mean?

    1. They suddenly grab and lock the wheels with only light pedal pressure
    2. They stop working only on the trailer, and the tractor brakes still hold
    3. They need less pressure to stop, because the heat makes them grip more
    4. You must apply them harder and harder to get the same stopping power

    Answer: D. Overheated brakes can keep fading until you cannot slow down or stop at all.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 56This means you have to apply them harder and harder to get the same stopping power.

  13. #13

    Why should you shift to a low gear before starting down a steep grade?

    1. Low gear is required by law on all hills
    2. It saves fuel on downgrades
    3. You may not be able to downshift once your speed has built up
    4. Low gear keeps the brakes cooler on upgrades

    Answer: C. After speed has built up you may not get into a lower gear, and engine braking is lost.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 57Do not try to downshift after your speed has already built up.

  14. #14

    On a long downgrade, you apply the brakes just hard enough to feel a definite slowdown and release them when your speed is reduced to about:

    1. five mph below your "safe" speed
    2. ten mph below your "safe" speed
    3. one mph below your "safe" speed
    4. twenty mph below your "safe" speed

    Answer: A. Example: with a safe speed of 40 mph, brake until about 35 mph, release, and repeat.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 57When your speed has been reduced to approximately five mph below your “safe” speed, release the brakes.

  15. #15

    Escape ramps slow a runaway vehicle by using:

    1. a paved downhill lane with speed bumps along its entire length
    2. concrete barriers across the lane that stop the vehicle at once
    3. a long bed of loose, soft material, sometimes with an upgrade
    4. a flat section covered with water to cool the brakes and tires

    Answer: C. Escape ramps are made to stop runaway vehicles safely without injuring drivers and passengers.

    Source: North Dakota CDL Manual (AAMVA model), Section 2, p. 57Escape ramps use a long bed of loose, soft material to slow a runaway vehicle, sometimes in combination with an upgrade.

  16. #16

    At 55 mph on dry pavement, the total minimum stopping distance (perception + reaction + braking) for a heavy vehicle is about:

    1. 150 feet
    2. 419 feet
    3. 1,000 feet
    4. 60 feet

    Answer: B. Perception 142 ft + reaction 61 ft + braking about 216 ft = about 419 ft.

    Source: Michigan CDL Manual (2022), 2.6.1

  17. #17

    If you double your speed (for example from 20 to 40 mph), your braking distance becomes about:

    1. The same
    2. Twice as long
    3. Three times as long
    4. Four times as long

    Answer: D. Doubling speed means about four times the braking distance and impact.

    Source: Michigan CDL Manual (2022), 2.6.1

  18. #18

    Compared with a loaded truck, an empty truck usually:

    1. Needs a longer distance to stop
    2. Needs a shorter distance to stop
    3. Needs the same distance to stop
    4. Cannot skid on any surface

    Answer: A. An empty vehicle has less traction, so it needs a greater stopping distance.

    Source: Michigan CDL Manual (2022), 2.6.1Empty trucks require greater stopping distances because an empty vehicle has less traction.

  19. #19

    Hydroplaning can occur at speeds as low as:

    1. 5 mph
    2. 15 mph
    3. 30 mph (with a lot of water)
    4. 70 mph only

    Answer: C. With enough water, hydroplaning can start around 30 mph.

    Source: Michigan CDL Manual (2022), 2.6.2

  20. #20

    If your vehicle is hydroplaning, you should:

    1. Brake hard
    2. Release the accelerator and push in the clutch
    3. Turn the wheel sharply
    4. Speed up

    Answer: B. Do not brake; release the accelerator and push in the clutch so the wheels can turn freely.

    Source: Michigan CDL Manual (2022), 2.6.2
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