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. In heavy traffic, what is generally the safest speed to travel?

   Correct answer: The speed of the other vehicles, if legal and safe

   The safest speed in heavy traffic is usually the speed of the vehicles around you, as long as it is legal and safe, since vehicles moving together are less likely to collide.

   Source: Missouri CDL Manual — Section 2.6: Controlling Speed

2. 2. By about how much should you reduce your speed on a wet road?

   Correct answer: By about one-third

   Wet roads can double stopping distance, so cut your speed by roughly one-third, for example slowing from 55 to about 35 mph.

   Source: Missouri CDL Manual — Section 2.6: Controlling Speed

3. 3. On packed snow, how much should you reduce your speed?

   Correct answer: By half or more

   On packed snow, cut your speed by half or more; if the surface turns icy, slow to a crawl and stop as soon as you safely can.

   Source: Missouri CDL Manual — Section 2.6: Controlling Speed

4. 4. What does perception distance refer to?

   Correct answer: The distance traveled from seeing a hazard until your brain recognizes it

   Perception distance is how far the vehicle rolls from the instant your eyes catch a hazard to the moment your brain registers it.

   Source: Missouri CDL Manual — Section 2.6: Controlling Speed

5. 5. Hydroplaning can begin at speeds as low as what, when a lot of water is on the road?

   Correct answer: 30 mph

   With enough water on the road, a vehicle can hydroplane at speeds as low as 30 mph, especially if tire pressure is low or tread is worn.

   Source: Missouri CDL Manual — Section 2.6: Controlling Speed

6. 6. What is the correct way to handle speed when approaching a curve?

   Correct answer: Slow to a safe speed before entering the curve

   Reduce to a safe speed ahead of the curve, since braking inside it makes the wheels easier to lock and cause a skid.

   Source: Missouri CDL Manual — Section 2.6: Controlling Speed

7. 7. When descending a long, steep grade, what is your main means of holding down your speed?

   Correct answer: The braking effect of the engine

   Rely on the engine's braking effect as your primary means of speed control on downgrades, saving the service brakes for when road and traffic force you to slow or stop.

   Source: Missouri CDL Manual — Section 2.6: Controlling Speed

8. 8. What is a danger of a load with a high center of gravity when taking curves?

   Correct answer: It makes the vehicle more likely to tip over

   A high center of gravity makes a vehicle more likely to tip over, which is most dangerous in curves or when swerving to avoid a hazard.

   Source: Missouri CDL Manual — Section 3.2: Weight and Balance

9. 9. If you double your speed, roughly how much longer is your braking distance?

   Correct answer: About four times as long

   Doubling speed, for example from 20 to 40 mph, makes the braking distance about four times as long.

   Source: Missouri CDL Manual — Section 2.6: Controlling Speed

10. 10. When your speed climbs above 40 mph, how should you adjust your following distance?

    Correct answer: Add one second

    Above 40 mph you should add one second to the following distance you calculated from your vehicle's length.

    Source: Missouri CDL Manual — Section 2.7: Managing Space

11. 11. At speeds under 40 mph, how much following distance does the manual suggest per 10 feet of vehicle length?

    Correct answer: One second for each 10 feet of length

    One good rule is to allow at least one second of following distance for every 10 feet of your vehicle's length when going under 40 mph.

    Source: Missouri CDL Manual — Section 2.7: Managing Space

12. 12. Why does an empty truck often need a greater stopping distance than a loaded one?

    Correct answer: Because an empty truck has less traction

    Brakes, tires, and suspension perform their best under a full load; an empty truck grips the road less, so it needs more room to stop.

    Source: Missouri CDL Manual — Section 2.6: Controlling Speed