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. Compared with a loaded truck, how does an empty truck's stopping distance behave?

   Correct answer: It needs more distance to stop because it has less traction

   An empty truck actually needs more stopping room; its brakes, tires, and springs perform best under a full load, so with no cargo it grips the road less.

   Source: Maryland CDL Manual — Section 2.6: Controlling Speed

2. 2. At 55 mph, roughly what is the total minimum stopping distance under ideal conditions?

   Correct answer: About 419 feet

   At 55 mph, perception (142 ft), reaction (61 ft), and braking (216 ft) add up to a minimum of about 419 feet.

   Source: Maryland CDL Manual — Section 2.6: Controlling Speed

3. 3. What three distances add together to make up total stopping distance?

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

   Total stopping distance is perception distance plus reaction distance plus braking distance.

   Source: Maryland CDL Manual — Section 2.6: Controlling Speed

4. 4. How can you measure your following distance in seconds?

   Correct answer: Note when the vehicle ahead passes a landmark, then count the seconds until you reach it

   After the vehicle in front crosses a shadow or road mark, count seconds ('one-thousand-one, one-thousand-two...') until your own front bumper reaches that point.

   Source: Maryland CDL Manual — Section 2.7: Managing Space

5. 5. When a traffic signal has been green for a long time as you approach, what should you expect?

   Correct answer: It will probably change soon, so be ready to slow and stop

   A light that has been green a long while will likely change before you reach it, so start slowing and be prepared to stop.

   Source: Maryland CDL Manual — Section 2.4: Looking Ahead and Managing Space

6. 6. About how much of a football-field length does a vehicle at 55 mph travel during the roughly 4.6 seconds a text takes your eyes off the road?

   Correct answer: About 371 feet — the length of a football field

   Research shows texting takes your eyes off the road an average of 4.6 seconds; at 55 mph that is roughly 371 feet, about a football field.

   Source: Maryland CDL Manual — Section 2.9: Distracted Driving

7. 7. At what speed can hydroplaning begin if there is enough water on the road?

   Correct answer: As low as 30 mph

   Hydroplaning can start at speeds as low as 30 mph when water is deep, and is more likely with low tire pressure or worn tread.

   Source: Maryland CDL Manual — Section 2.6: Controlling Speed

8. 8. Why can an empty cargo van be a problem for overhead clearance?

   Correct answer: An empty van sits higher than a loaded one, so it may not fit where it did when loaded

   The weight of cargo lowers a van; when empty it rides higher, so clearing an underpass loaded does not guarantee clearing it empty.

   Source: Maryland CDL Manual — Section 2.7: Managing Space

9. 9. Why should you slow to a safe speed before entering a curve rather than braking in it?

   Correct answer: Braking in a curve can lock the wheels and cause a skid, and speed can cause rollover

   Slow down before the curve; braking in it makes wheel lockup and skidding easier, and a high center of gravity can roll the vehicle even at the posted curve speed.

   Source: Maryland CDL Manual — Section 2.6: Controlling Speed

10. 10. What is the main way to control your speed on a long, steep downgrade?

    Correct answer: Use the braking effect of the engine in a low gear, saving the brakes

    Engine braking in a low gear is the primary speed control on a downgrade; save the service brakes so they can slow or stop you when needed.

    Source: Maryland CDL Manual — Section 2.6: Controlling Speed

11. 11. By roughly how much should you cut your speed on a wet road?

    Correct answer: About one-third — for example, from 55 to about 35 mph

    Wet roads can double stopping distance, so reduce speed by about a third; cut it in half on packed snow, and to a crawl on ice.

    Source: Maryland CDL Manual — Section 2.6: Controlling Speed

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

    Correct answer: The speed of the traffic around you, without exceeding legal or safe limits

    Vehicles moving the same direction at the same speed rarely collide, so travel with the flow of traffic when it is legal and safe.

    Source: Maryland CDL Manual — Section 2.6: Controlling Speed