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. How does the '1 second per 10 feet of length' following rule change at higher speed?

   Correct answer: Add 1 second when you are going faster than 40 mph

   When you are going faster than 40 mph, add 1 second to the figure the length rule gives you. So a 60-foot vehicle needs 6 seconds under 40 mph and 7 seconds above 40 mph.

   Source: Texas CDL Handbook — Space Ahead

2. 2. Before starting down a long, steep downgrade, you should:

   Correct answer: Choose a safe speed and a low gear before you start down

   Choose a safe speed and shift to a low gear before you start down. Trying to downshift after you are already rolling fast down the grade is much harder and less safe.

   Source: Texas CDL Handbook — Driving Down Long Grades

3. 3. The total distance it takes to stop a commercial vehicle is made up of:

   Correct answer: Perception distance, reaction distance, and braking distance

   Total stopping distance = perception distance + reaction distance + braking distance. All three add together to determine how far you travel before stopping.

   Source: Texas CDL Handbook — Controlling Your Speed

4. 4. Compared with a fully loaded truck, an empty truck usually needs:

   Correct answer: A longer distance to stop

   An empty truck has less traction because there is less weight pressing the tires down, and its stiff suspension can make the tires bounce. As a result an empty truck can take a longer distance to stop.

   Source: Texas CDL Handbook — Speed and Stopping Distance

5. 5. Using the basic rule, how much following distance should you keep behind a 40-foot vehicle traveling below 40 mph?

   Correct answer: About 4 seconds

   Allow 1 second of following distance for every 10 feet of vehicle length at speeds under 40 mph. A 40-foot vehicle needs about 4 seconds; add 1 more second above 40 mph.

   Source: Texas CDL Handbook — Space Ahead

6. 6. Braking too much on a long downgrade can cause:

   Correct answer: Brake fade, a loss of braking power from overheating

   Continuous hard braking overheats the brakes and causes brake fade, where they lose their stopping power. That is why the engine should do most of the work on a downgrade.

   Source: Texas CDL Handbook — Brake Fade

7. 7. Because of 'off-tracking,' when a long vehicle rounds a turn its rear wheels:

   Correct answer: Follow a shorter path, to the inside of the turn

   In a turn the rear wheels follow a shorter path than the front wheels, tracking to the inside of the turn. The longer the vehicle, the more the rear wheels off-track.

   Source: Texas CDL Handbook — Turning and Off-Tracking

8. 8. On a long downgrade, the main way you should control your speed is by:

   Correct answer: Engine braking in a properly chosen low gear

   The engine's braking effect in a properly chosen low gear is the primary way to control speed on a downgrade. Use the service brakes only to supplement it, so they do not overheat.

   Source: Texas CDL Handbook — Driving Down Long Grades

9. 9. What is the safest way to take a curve in a large vehicle?

   Correct answer: Slow down before the curve, then accelerate gently through it

   Slow to a safe speed before you enter the curve, then accelerate gently through it. Braking hard while in a curve can cause a skid or a rollover.

   Source: Texas CDL Handbook — Speed and Curves

10. 10. Hydroplaning, where the tires ride on a film of water instead of the road, is most likely when:

    Correct answer: The road is wet and you drive too fast on worn or under-inflated tires

    Hydroplaning happens on wet roads, especially at higher speeds and with worn or under-inflated tires. If it occurs, ease off the accelerator and keep the wheel straight until the tires grip again.

    Source: Texas CDL Handbook — Wet Roads and Hydroplaning

11. 11. Why should you avoid driving right alongside another vehicle on a multi-lane road?

    Correct answer: You could be trapped with no room to change lanes if a hazard appears

    Traveling beside another vehicle can trap you with no room to escape a hazard, and the other driver might change lanes into you. Drop back or move ahead so you keep an open space.

    Source: Texas CDL Handbook — Space to the Sides

12. 12. When you need to cross or pull into traffic with a heavy vehicle, remember that:

    Correct answer: You need a much larger gap than a car does

    Because of its size and weight your vehicle accelerates slowly, so it needs a much larger gap in traffic than a car would. Wait for a gap big enough to get fully up to speed.

    Source: Texas CDL Handbook — Space to Cross or Enter Traffic