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 perception distance?

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

   Perception distance covers the ground you travel between first spotting a hazard and your mind registering it.

   Source: Connecticut CDL Manual - Section 2: Driving Safely

2. 2. Below 40 mph, what is the rule of thumb for following distance based on vehicle length?

   Correct answer: One second for every 10 feet of length

   Allow a minimum of one second of gap per 10 feet of your vehicle's length whenever you travel under 40 mph.

   Source: Connecticut CDL Manual - Section 2: Driving Safely

3. 3. At 55 mph in ideal conditions, the total stopping distance is at least about how far?

   Correct answer: About 419 feet

   At 55 mph an average driver needs a minimum of about 419 feet to stop, more than the length of a football field.

   Source: Connecticut CDL Manual - Section 2: Driving Safely

4. 4. Total stopping distance is made up of which three parts?

   Correct answer: Perception, reaction, and braking distance

   Total stopping distance adds perception distance, reaction distance, and braking distance together.

   Source: Connecticut CDL Manual - Section 2: Driving Safely

5. 5. Regarding overhead clearance, how does an empty cargo van compare to a loaded one?

   Correct answer: An unloaded van sits higher than one that is loaded

   An empty van rides higher than a loaded one, so clearing a bridge loaded does not guarantee you will clear it empty.

   Source: Connecticut CDL Manual - Section 2: Driving Safely

6. 6. If your speed rises from 20 up to 40 mph, about how much longer does the braking distance become?

   Correct answer: Four times as long

   Doubling the speed makes both the impact and the braking distance about four times greater.

   Source: Connecticut CDL Manual - Section 2: Driving Safely

7. 7. On a long downgrade, what should be your main way of controlling speed?

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

   The braking effect of the engine, achieved with a low gear, is the principal way to control speed on downgrades so brakes do not overheat.

   Source: Connecticut CDL Manual - Section 2: Driving Safely

8. 8. By about how much should you reduce 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, such as from 55 to about 35 mph.

   Source: Connecticut CDL Manual - Section 2: Driving Safely

9. 9. How many seconds of following distance should a 40-foot vehicle keep at speeds below 40 mph?

   Correct answer: 4 seconds

   At one second per 10 feet, a 40-foot vehicle needs about 4 seconds below 40 mph.

   Source: Connecticut CDL Manual - Section 2: Driving Safely

10. 10. Hydroplaning can begin at speeds as low as what, when there is a lot of water?

    Correct answer: 30 mph

    With enough standing water, a vehicle can hydroplane at speeds as low as 30 mph, more so with low tire pressure or worn tread.

    Source: Connecticut CDL Manual - Section 2: Driving Safely

11. 11. When you drive faster than 40 mph, how do you adjust the following-distance rule?

    Correct answer: Add one second

    Above 40 mph you add one second for safety to the seconds figured from your vehicle length.

    Source: Connecticut CDL Manual - Section 2: Driving Safely

12. 12. Why do empty trucks require a greater stopping distance than loaded ones?

    Correct answer: Because an empty vehicle has less traction

    An empty truck has less traction, so its brakes, designed to work best fully loaded, need more distance to stop.

    Source: Connecticut CDL Manual - Section 2: Driving Safely