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 what speed can hydroplaning begin if enough water is on the road?

   Correct answer: As low as 30 mph

   Where water pools deeply, hydroplaning may start at just 30 mph, and low tire pressure or worn tread makes it worse.

   Source: Utah CDL Manual — Section 2: Driving Safely (Hydroplaning)

2. 2. Compared with a loaded cargo van, how does an empty one's height compare?

   Correct answer: The empty van is higher

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

   Source: Utah CDL Manual — Section 2: Driving Safely (Space Overhead)

3. 3. When traffic is heavy, what is generally the safest speed to travel?

   Correct answer: The speed of surrounding traffic

   In heavy traffic the safest choice is to move with the flow, since vehicles going the same way at the same speed are least likely to collide.

   Source: Utah CDL Manual — Section 2: Driving Safely (Speed and Traffic Flow)

4. 4. What is the main way to control your speed when going down a long, steep grade?

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

   The engine's braking effect, greatest in a low gear near governed rpm, is the principal means of holding speed downhill, saving the brakes for when needed.

   Source: Utah CDL Manual — Section 2: Driving Safely (Speed on Downgrades)

5. 5. How far does a vehicle at 55 mph travel during the roughly two seconds a driver can be blinded by glare?

   Correct answer: More than half a football field

   At 55 mph, two seconds of glare blindness carries the vehicle more than half the length of a football field before vision recovers.

   Source: Utah CDL Manual — Section 2: Driving Safely (Glare)

6. 6. Why should you allow a larger gap than a car would when pulling a heavy vehicle into traffic?

   Correct answer: Slow acceleration and the space the vehicle needs

   Large vehicles accelerate slowly and take up more room, so you need a much bigger gap, especially when heavily loaded, to enter traffic safely.

   Source: Utah CDL Manual — Section 2: Driving Safely (Crossing or Entering Traffic)

7. 7. At 50 mph in a 60-foot rig, how many seconds should separate you from the vehicle ahead?

   Correct answer: 7 seconds

   A 60-foot vehicle needs 6 seconds below 40 mph; above that speed you add one second, for a total of 7 seconds.

   Source: Utah CDL Manual — Section 2: Driving Safely (Space Ahead)

8. 8. At speeds below 40 mph, how much following distance does the manual's rule recommend?

   Correct answer: One second per 10 feet of your rig's length

   The rule is at least one second of following room per 10 feet of vehicle length below 40 mph, adding one more second above that speed.

   Source: Utah CDL Manual — Section 2: Driving Safely (Space Ahead)

9. 9. By how much should you cut your speed on a road that is merely wet?

   Correct answer: By about one-third

   Wet roads can double stopping distance, so reduce speed by about one-third, for example from 55 down to around 35 mph.

   Source: Utah CDL Manual — Section 2: Driving Safely (Matching Speed to Surface)

10. 10. How should you handle your speed before entering a curve in a heavy vehicle?

    Correct answer: Slow down before entering, not during the curve

    Reduce to a safe speed ahead of the curve, since braking inside it can lock the wheels and start a skid.

    Source: Utah CDL Manual — Section 2: Driving Safely (Speed and Curves)

11. 11. Going twice as fast, from 20 up to 40 mph, roughly multiplies your braking distance by how much?

    Correct answer: About four times as long

    Doubling speed multiplies both the impact force and the braking distance by about four times.

    Source: Utah CDL Manual — Section 2: Driving Safely (Effect of Speed)

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

    Correct answer: By one-half or more

    Packed snow calls for cutting speed by a half or more; ice means slowing to a crawl and stopping as soon as it is safe.

    Source: Utah CDL Manual — Section 2: Driving Safely (Matching Speed to Surface)