Doubles & Triples Test
Doubles & Triples Test – 20 Questions with Answers
20 questions · 15 min · Medium
Alabama CDL Exam Simulator – 20 Questions with Answers
Simulate the Alabama CDL knowledge test with 20 practice questions covering general commercial driving knowledge, vehicle inspection, air brakes, combination vehicles, safe driving, cargo, hazardous materials, and commercial driver responsibilities.
- 20
- Questions
- 15 min
- Time limit
- Medium
- Difficulty
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All 20 questions and answers Spoilers: this shows the questions and answers. Try the quiz first! Open
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1. What is the main purpose of a pre-trip inspection?
- A. To increase fuel economy
- B. To identify safety defects before operating the vehicle
- C. To increase the vehicle's maximum speed
- D. To reduce cargo weight
Show answer
B. To identify safety defects before operating the vehicle
A pre-trip inspection helps identify defective or unsafe equipment before the commercial vehicle is operated.
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2. Why is it important to maintain a safe following distance when driving a commercial vehicle?
- A. It prevents other vehicles from passing
- B. It gives you more time and space to react
- C. It increases engine power
- D. It eliminates brake lag
Show answer
B. It gives you more time and space to react
Commercial vehicles can require significant stopping distance, so maintaining adequate space provides more time to respond to hazards.
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3. What does the air compressor do in an air brake system?
- A. Stores fuel
- B. Generates compressed air
- C. Controls steering
- D. Cools the brake drums
Show answer
B. Generates compressed air
The air compressor produces compressed air and supplies it to the air reservoirs used by the braking system.
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4. What does a low-air-pressure warning indicate?
- A. The fuel tank is nearly empty
- B. Air pressure in the braking system is dangerously low
- C. The engine temperature is too high
- D. The tires are overinflated
Show answer
B. Air pressure in the braking system is dangerously low
The low-air warning alerts the driver when air pressure has dropped to a potentially dangerous level.
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5. What is brake lag?
- A. The delay caused by air traveling through the brake system
- B. The time needed to refuel a truck
- C. The time needed to inspect the tires
- D. The delay caused by changing gears
Show answer
A. The delay caused by air traveling through the brake system
Air brakes have a slight delay because compressed air must travel through the system before the brakes apply.
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6. What is trailer off-tracking?
- A. When a trailer's wheels follow a shorter path than the tractor during a turn
- B. When the trailer loses electrical power
- C. When the trailer brakes stop working
- D. When the trailer becomes disconnected
Show answer
A. When a trailer's wheels follow a shorter path than the tractor during a turn
During a turn, the trailer wheels generally track inside the path of the tractor. This is called off-tracking.
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7. What is the purpose of the fifth wheel on a tractor?
- A. To connect the tractor to the trailer
- B. To store compressed air
- C. To control the trailer lights
- D. To measure tire pressure
Show answer
A. To connect the tractor to the trailer
The fifth wheel provides the coupling connection between the tractor and a semi-trailer.
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8. What should you do if you miss your intended highway exit?
- A. Reverse on the highway
- B. Make a sudden U-turn
- C. Continue to the next exit and safely reroute
- D. Use the shoulder to return to the exit
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C. Continue to the next exit and safely reroute
Missing an exit does not justify a dangerous maneuver. Continue safely and use another exit or route.
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9. Why is proper cargo securement important?
- A. It prevents cargo from shifting or falling
- B. It increases the vehicle's top speed
- C. It eliminates the need for inspections
- D. It reduces the vehicle's weight
Show answer
A. It prevents cargo from shifting or falling
Proper cargo securement helps prevent cargo from moving, falling, or creating a hazard for other road users.
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10. What can happen if cargo is loaded too high on a commercial vehicle?
- A. The center of gravity becomes higher
- B. The vehicle becomes more stable
- C. The stopping distance becomes shorter
- D. The brakes become stronger
Show answer
A. The center of gravity becomes higher
A higher center of gravity can reduce stability and increase the risk of rollover.
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11. What should you do when approaching a sharp curve in a commercial vehicle?
- A. Accelerate before entering the curve
- B. Reduce speed before entering the curve
- C. Brake hard while turning
- D. Drive over the center line
Show answer
B. Reduce speed before entering the curve
Reducing speed before the curve helps maintain control and reduces the risk of skidding or rollover.
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12. What should you do when driving in heavy rain?
- A. Increase speed
- B. Reduce speed and increase following distance
- C. Follow the vehicle ahead closely
- D. Turn off your headlights
Show answer
B. Reduce speed and increase following distance
Heavy rain can reduce visibility and traction. Slowing down and increasing following distance provides additional safety.
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13. What should you do if your commercial vehicle begins to hydroplane?
- A. Brake hard immediately
- B. Turn sharply
- C. Ease off the accelerator and avoid sudden movements
- D. Accelerate rapidly
Show answer
C. Ease off the accelerator and avoid sudden movements
Sudden braking, steering, or acceleration can cause loss of control. Gradually easing off the accelerator can help restore traction.
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14. What should you do when an emergency vehicle approaches with flashing lights and a siren?
- A. Speed up to stay ahead
- B. Move to the right and stop when safe
- C. Stop immediately in the center of the road
- D. Continue at the same speed
Show answer
B. Move to the right and stop when safe
Drivers should yield to emergency vehicles using audible and visual warning signals and move to the right and stop when safe.
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15. What should you do at a railroad crossing if there is not enough room on the other side for your entire vehicle?
- A. Enter the crossing and wait
- B. Stop before the tracks
- C. Cross quickly
- D. Drive onto the shoulder
Show answer
B. Stop before the tracks
Never enter a railroad crossing unless there is enough space for the entire vehicle to completely clear the tracks.
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16. What should you do before changing lanes in a commercial vehicle?
- A. Check mirrors and blind spots and signal
- B. Only check the rearview mirror
- C. Change lanes immediately if the lane appears empty
- D. Accelerate without signaling
Show answer
A. Check mirrors and blind spots and signal
Commercial vehicles have large blind spots, so drivers should check mirrors and blind spots and signal before changing lanes.
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17. Which action can help prevent brake overheating on a long, steep downgrade?
- A. Use a lower gear and appropriate braking techniques
- B. Shift into neutral
- C. Rely continuously on heavy service braking
- D. Accelerate downhill
Show answer
A. Use a lower gear and appropriate braking techniques
Using an appropriate lower gear provides engine braking and helps reduce excessive use of the service brakes.
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18. What should you do if you become fatigued while driving a commercial vehicle?
- A. Increase speed to reach your destination sooner
- B. Turn up the radio
- C. Stop at a safe location and rest
- D. Open a window and continue
Show answer
C. Stop at a safe location and rest
Fatigue reduces alertness and reaction time. A fatigued driver should stop and rest rather than continue driving.
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19. What is an important reason to check mirrors frequently while operating a commercial vehicle?
- A. To monitor surrounding traffic and blind spots
- B. To increase engine power
- C. To control tire pressure
- D. To reduce cargo weight
Show answer
A. To monitor surrounding traffic and blind spots
Frequent mirror checks help the driver monitor traffic around the vehicle and identify vehicles that may not be visible directly.
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20. What is a key responsibility of a commercial driver?
- A. Always drive at the maximum posted speed
- B. Operate the vehicle safely and comply with applicable laws and regulations
- C. Ignore minor equipment defects
- D. Avoid required inspections
Show answer
B. Operate the vehicle safely and comply with applicable laws and regulations
Commercial drivers are responsible for safe vehicle operation, required inspections, and compliance with applicable traffic and commercial driving requirements.