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. What is the basic rule for following distance at speeds below 40 mph?

   Correct answer: One second per 10 feet of vehicle length

   Leave at least one second for each 10 feet of vehicle length at speeds below 40 mph.

   Source: Oregon Commercial Driver Manual, Section 2.7.1 - Space Ahead

2. 2. What should be your main way of controlling speed on a long downgrade?

   Correct answer: Use the braking effect of the engine as your main control

   You must use the braking effect of the engine as the principal way of controlling your speed on downgrades.

   Source: Oregon Commercial Driver Manual, Section 2.6.6 - Speed on Downgrades

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

   Correct answer: The same speed as the other traffic

   In heavy traffic the safest speed is the speed of the other vehicles going the same direction.

   Source: Oregon Commercial Driver Manual, Section 2.6.5 - Speed and Traffic Flow

4. 4. How many seconds of following distance should a 60-foot rig keep at speeds below 40 mph?

   Correct answer: About six seconds

   At one second per 10 feet, a 60-foot rig needs about six seconds of following distance below 40 mph.

   Source: Oregon Commercial Driver Manual, Section 2.7.1 - Space Ahead

5. 5. About how much should you reduce your speed on packed snow?

   Correct answer: By about a half

   On packed snow, reduce your speed by a half or more.

   Source: Oregon Commercial Driver Manual, Section 2.6.2 - Matching Speed to the Road Surface

6. 6. Why can't you rely on the fact that you fit under a bridge while loaded?

   Correct answer: An empty van is taller, so past clearance is no guarantee

   The weight of a cargo van changes its height; an empty van is higher than a loaded one, so past clearance is no guarantee.

   Source: Oregon Commercial Driver Manual, Section 2.7.4 - Space Overhead

7. 7. At 55 mph, about what is the minimum total stopping distance for a heavy vehicle?

   Correct answer: A minimum of about 419 feet

   At 55 mph, with perception, reaction, and braking considered, your vehicle travels a minimum of about 419 feet before stopping.

   Source: Oregon Commercial Driver Manual, Section 2.6.1 - Stopping Distance

8. 8. About how much should you reduce your speed on a wet road?

   Correct answer: By about one-third

   On a wet road, reduce your speed by about one-third, for example from 55 to about 35 mph.

   Source: Oregon Commercial Driver Manual, Section 2.6.2 - Matching Speed to the Road Surface

9. 9. Why do empty trucks generally require greater stopping distances than loaded ones?

   Correct answer: They need more distance because of less traction

   An empty vehicle has less traction because the brakes and tires work best when the vehicle is loaded, so it needs more distance to stop.

   Source: Oregon Commercial Driver Manual, Section 2.6.1 - Stopping Distance

10. 10. What three distances add up to total stopping distance?

    Correct answer: Perception, reaction, and braking distance

    Total stopping distance is the sum of perception distance, reaction distance, and braking distance.

    Source: Oregon Commercial Driver Manual, Section 2.6.1 - Stopping Distance

11. 11. At 60 mph, how does your stopping distance compare to the length of a football field?

    Correct answer: It is longer than a football field

    At 60 mph, your stopping distance is greater than the length of a football field.

    Source: Oregon Commercial Driver Manual, Section 2.6.1 - Stopping Distance

12. 12. What can happen if you take a curve too fast in a heavy vehicle?

    Correct answer: You may skid off the road or roll the vehicle over

    If you take a curve too fast, the tires can lose traction and you skid off the road, or the vehicle can roll over.

    Source: Oregon Commercial Driver Manual, Section 2.6.3 - Speed and Curves