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. At highway speed, looking "12 to 15 seconds" ahead means watching about how far down the road?

   Correct answer: About a quarter of a mile

   At highway speed, looking 12 to 15 seconds ahead means watching about a quarter of a mile down the road; at lower speeds it is roughly one block.

   Source: Massachusetts CDL Manual — Section 2.4: Seeing

2. 2. A 40-foot vehicle traveling over 40 mph should keep how many seconds of following distance?

   Correct answer: 5 seconds

   A 40-foot vehicle needs 4 seconds below 40 mph, and one extra second is added above 40 mph, for a total of 5 seconds.

   Source: Massachusetts CDL Manual — Section 2.7: Managing Space

3. 3. Of all the space around your vehicle, which area is the most important to manage?

   Correct answer: The space ahead of you

   The space ahead — the area you are driving into — is the most important, because the vehicle trucks and buses most often strike is the one directly in front of them.

   Source: Massachusetts CDL Manual — Section 2.7: Managing Space

4. 4. Why is it dangerous to brake while your vehicle is already in a curve?

   Correct answer: It makes it easier to lock the wheels and skid

   Braking once you are in a curve makes wheel lockup and a skid more likely, so slow to a safe speed beforehand and never top the posted curve speed.

   Source: Massachusetts CDL Manual — Section 2.6: Controlling Speed

5. 5. What is your most important way of controlling speed on a long, steep downgrade?

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

   Rely on engine braking as your chief means of holding speed down the hill; it works best near the governed rpm in a low gear, which spares the service brakes for when you truly need them.

   Source: Massachusetts CDL Manual — Section 2.6: Controlling Speed

6. 6. If you go from 20 mph up to 40 mph, roughly what happens to the braking distance?

   Correct answer: It becomes about four times as long

   Doubling the speed makes the braking distance about four times as long and the impact about four times greater; tripling the speed makes both about nine times greater.

   Source: Massachusetts CDL Manual — Section 2.6: Controlling Speed

7. 7. At about what speed can hydroplaning begin when there is a lot of water on the road?

   Correct answer: As low as 30 mph

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

   Source: Massachusetts CDL Manual — Section 2.6: Controlling Speed

8. 8. How much following distance does the manual recommend at speeds below 40 mph?

   Correct answer: One second for every 10 feet of vehicle length

   Below 40 mph, allow about one second of following distance for each 10 feet of your vehicle's length; above 40 mph, add one more second.

   Source: Massachusetts CDL Manual — Section 2.7: Managing Space

9. 9. On packed snow, how much should you reduce your speed?

   Correct answer: By half or more

   On packed snow, cut your speed by half or more; if the surface turns to ice, slow to a crawl and stop as soon as you safely can.

   Source: Massachusetts CDL Manual — Section 2.6: Controlling Speed

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

    Correct answer: The speed of the other vehicles, if legal

    In heavy traffic the safest pace is that of the vehicles around you, provided it stays legal, because traffic all headed one way at a matching speed rarely collides.

    Source: Massachusetts CDL Manual — Section 2.6: Controlling Speed

11. 11. What should you do first if your vehicle begins to hydroplane?

    Correct answer: Release the accelerator and push in the clutch

    When hydroplaning, ease off the accelerator and press in the clutch so the wheels can slow and spin freely; braking to slow the truck should be avoided.

    Source: Massachusetts CDL Manual — Section 2.6: Controlling Speed

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

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

    Total stopping distance is the sum of perception distance, reaction distance, and braking distance — the ground covered from seeing a hazard to coming to a full stop.

    Source: Massachusetts CDL Manual — Section 2.6: Controlling Speed