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. Using your brakes too much on a long downgrade can cause:

   Correct answer: Brake fade, in which the brakes lose stopping power from overheating

   Excessive braking overheats the brakes and causes brake fade — the brakes lose their stopping power. That is why the engine, not the service brakes, should do most of the work on a downgrade.

   Source: New York CDL Manual — Controlling Speed on Downgrades

2. 2. You are driving a 40-foot vehicle at 50 mph. About how many seconds of following distance should you keep?

   Correct answer: About 5 seconds

   At 40 feet you need 4 seconds under 40 mph (1 second per 10 feet). Because you are traveling over 40 mph, add 1 more second, for a total of about 5 seconds.

   Source: New York CDL Manual — Managing Space

3. 3. Before you start down a long, steep downgrade, you should:

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

   Select a safe speed and shift into a low gear before you start down the grade. It is much harder — and often impossible — to downshift safely once you are already descending and picking up speed.

   Source: New York CDL Manual — Controlling Speed on Downgrades

4. 4. On a wet road you should generally reduce your speed by about:

   Correct answer: One-third

   Cut your speed by about one-third on a wet road (for example, from 55 to roughly 35 mph). On packed snow reduce speed by half or more, and on ice slow to a crawl or get off the road.

   Source: New York CDL Manual — Controlling Speed

5. 5. If you double your speed from 20 mph to 40 mph, your braking distance becomes about:

   Correct answer: Four times as long

   Braking distance increases with the square of speed. Doubling your speed roughly quadruples the distance needed to stop, which is why small increases in speed greatly increase stopping distance.

   Source: New York CDL Manual — Controlling Speed

6. 6. A driver is following you too closely (tailgating). One good response is to:

   Correct answer: Increase the space ahead of you so you can slow gradually

   You can't stop others from tailgating, but you can open up more space ahead of you so you won't have to brake suddenly, and let the tailgater pass. Never speed up or brake hard to discourage them.

   Source: New York CDL Manual — Managing Space

7. 7. On dry pavement at about 55 mph, the total stopping distance for a typical loaded truck is closest to:

   Correct answer: Greater than the length of a football field (about 300 feet or more)

   At 55 mph, perception, reaction, and braking distance add up to more than 400 feet for a heavy vehicle, which is greater than the length of a football field. That is far more than most drivers expect, so keep plenty of space ahead.

   Source: New York State CDL Manual — Controlling Speed

8. 8. Why must you pay attention to posted clearance heights at bridges and overpasses?

   Correct answer: Striking a low bridge or wires can damage the vehicle or cargo, so you must be sure you have enough clearance

   You need enough overhead room for your vehicle's height. Posted clearances can be lower than marked after repaving, and hitting a low bridge or wires can wreck your vehicle or cargo, so be sure you fit before you go under.

   Source: New York CDL Manual — Managing Space

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

   Correct answer: Requires a greater stopping distance because it has less traction

   Empty trucks can take longer to stop. With less weight, the tires have less traction and can bounce and lock up, so the brakes work less effectively than when the vehicle is properly loaded.

   Source: New York CDL Manual — Controlling Speed

10. 10. Total stopping distance for a commercial vehicle is made up of three parts. They are:

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

    Total stopping distance = perception distance + reaction distance + braking distance. It is how far your vehicle travels from the moment you see a hazard until the vehicle comes to a complete stop.

    Source: New York CDL Manual — Controlling Speed

11. 11. As you approach a curve, the safest practice is to:

    Correct answer: Slow down before entering, then keep a steady speed through the curve

    Slow to a safe speed before you enter the curve, then hold a steady speed or accelerate gently through it. Braking hard in a curve can make the vehicle skid or roll over, and posted curve speeds may be too fast for a loaded truck.

    Source: New York CDL Manual — Controlling Speed

12. 12. On a long downgrade, your main way to control speed should be:

    Correct answer: The braking effect of the engine in a low gear

    The braking effect of the engine in a low gear is the primary way to control speed on a long grade. Use the service brakes only to supplement it, so they do not overheat and fade.

    Source: New York CDL Manual — Controlling Speed on Downgrades