Speed & Space Management

Study questions with answers

12 sample Speed & Space Management questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.

1. 1. On a wet road, by about how much should you reduce your speed?

   Correct answer: By about one-third, such as 55 down to about 35 mph

   Cut your speed by roughly one-third on a wet road, for example from 55 down to about 35 mph.

   Source: Michigan CDL Manual, Section 2.6.2 (Slippery surfaces)

2. 2. What should be your principal means of controlling speed on a long downgrade?

   Correct answer: The braking effect of the engine, aided by a low gear

   Use the braking effect of the engine, helped by a low gear, as your main way to control speed on a downgrade; save the service brakes.

   Source: Michigan CDL Manual, Section 2.6.6 (Speed on downgrades)

3. 3. Hydroplaning can begin at speeds as low as what, when a lot of water is present?

   Correct answer: 30 mph

   With enough standing water, hydroplaning can start at speeds as low as 30 mph, and it is more likely with low tire pressure or worn tread.

   Source: Michigan CDL Manual, Section 2.6.2 (Hydroplaning)

4. 4. Wet roads can do what to your stopping distance?

   Correct answer: Double it

   A wet road can double your stopping distance, so you must slow down to stop in the same space as on a dry road.

   Source: Michigan CDL Manual, Section 2.6.2 (Slippery surfaces)

5. 5. When should you shift into a low gear for a steep downgrade?

   Correct answer: Before you start down the grade

   Shift to low gear before you start down; after speed builds, dropping into a lower gear may become impossible.

   Source: Michigan CDL Manual, Section 2.16.2 (Select the right gear)

6. 6. Why do empty trucks often need a longer stopping distance than loaded ones?

   Correct answer: An empty vehicle has less traction

   An empty vehicle grips the road less, and its brakes, tires, and suspension perform best under a full load.

   Source: Michigan CDL Manual, Section 2.6.1 (Effect of vehicle weight)

7. 7. Why must trucks slow down before entering a curve?

   Correct answer: A high center of gravity can cause a rollover, even at the posted speed for the curve

   A high center of gravity can cause a rollover, sometimes even at the posted speed for the curve, so slow before entering.

   Source: Michigan CDL Manual, Section 2.6.3 (Speed and curves)

8. 8. On packed snow, how much should you cut your speed?

   Correct answer: By about half or more

   Reduce your speed by about half or more on packed snow; on ice, slow to a crawl and stop as soon as it is safe.

   Source: Michigan CDL Manual, Section 2.6.2 (Slippery surfaces)

9. 9. Total stopping distance is the sum of which three distances?

   Correct answer: Perception, reaction, and braking distance

   Total stopping distance combines perception distance, reaction distance, and braking distance.

   Source: Michigan CDL Manual, Section 2.6.1 (Stopping distance)

10. 10. For a 40-foot vehicle traveling under 40 mph, what following distance in seconds is recommended?

    Correct answer: 4 seconds

    At one second per 10 feet, a 40-foot vehicle needs 4 seconds below 40 mph, and 5 seconds above 40 mph.

    Source: Michigan CDL Manual, Section 2.7.1 (Space ahead)

11. 11. Below 40 mph, how much following distance does the one-second rule suggest?

    Correct answer: One second for every 10 feet of vehicle length

    Below 40 mph, allow about one second for every 10 feet of your vehicle's length.

    Source: Michigan CDL Manual, Section 2.7.1 (Space ahead)

12. 12. If your vehicle begins to hydroplane, how should you regain control?

    Correct answer: Release the accelerator and push in the clutch so the wheels turn freely

    Release the accelerator and push in the clutch so the wheels slow and can turn freely; do not brake while hydroplaning.

    Source: Michigan CDL Manual, Section 2.6.2 (Hydroplaning)