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Alabama CDL General Knowledge study materials
Alabama CDL General Knowledge study resources

Alabama CDL General Knowledge practice questions

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Question 1Driving Safely

When driving a commercial vehicle at night, at what distance should you switch your high-beam headlights to low beams when meeting an oncoming vehicle?

  1. Within 500 feet of the oncoming vehicle Correct answer.
  2. Within 1,000 feet of the oncoming vehicle
  3. Within 200 feet of the oncoming vehicle
  4. Only after the vehicle has passed you

Explanation

You must dim your high beams when an oncoming vehicle is within 500 feet so you do not blind the other driver. Dimming earlier is acceptable, but 500 feet is the required minimum distance.

Question 2Driving Safely

You are driving a loaded tractor-trailer and need to stop quickly. What is the safest braking technique?

  1. Apply steady, firm pressure to the brake pedal Correct answer.
  2. Apply the trailer brake only
  3. Pump the brake pedal rapidly to avoid a skid
  4. Shift to neutral and coast to a stop

Explanation

With air brakes you brake by applying steady, controlled pressure to the pedal. Fanning or pumping the pedal wastes air pressure and reduces braking power. Coasting in neutral removes engine braking and control.

Question 3Driving Safely

How far before a turn should you begin signaling in a commercial vehicle?

  1. At least 50 feet
  2. At least 100 feet Correct answer.
  3. At least 500 feet
  4. At least 200 feet

Explanation

You should signal at least 100 feet before a turn so other drivers have time to react. Signaling too late gives surrounding traffic little warning of your intended move.

Question 4Driving Safely

What is the proper way to hold the steering wheel for maximum control?

  1. Both hands on opposite sides of the wheel Correct answer.
  2. One hand at the bottom of the wheel
  3. One hand at the top of the wheel
  4. Fingertips at the top of the wheel

Explanation

Holding the wheel with both hands on opposite sides gives you the best control and lets you turn quickly if needed. One-handed or fingertip grip reduces control, especially during sudden maneuvers.

Question 5Driving Safely

When must you use your four-way flashers while driving?

  1. Whenever you are in heavy traffic
  2. Only when parked on the shoulder
  3. When you are driving slowly enough to be a hazard to other traffic Correct answer.
  4. Whenever you are driving below the speed limit

Explanation

Four-way flashers warn other drivers when your vehicle is moving slowly enough to be a traffic hazard. They are not for routine driving or merely being below the limit.

Question 6Driving Safely

What is the minimum following distance you should maintain behind another vehicle under ideal conditions?

  1. Four seconds
  2. One second
  3. Two seconds Correct answer.
  4. Six seconds

Explanation

Under ideal conditions, keep at least a two-second gap behind the vehicle ahead. At higher speeds or in poor conditions you should increase the gap.

Question 7Driving Safely

You are driving a 60-foot combination vehicle. How much additional following distance should you allow compared to a passenger car?

  1. About one second
  2. About two seconds Correct answer.
  3. About three seconds
  4. No additional distance is needed

Explanation

Longer combination vehicles need more stopping distance, so add about one second for each 10 feet of vehicle length beyond the first 40 feet. A 60-foot vehicle therefore needs roughly two extra seconds.

Question 8Driving Safely

What does the term 'blind spot' refer to for a commercial driver?

  1. The area covered by the backup camera
  2. The area directly in front of the hood
  3. The area illuminated by high beams
  4. The area alongside and behind the vehicle that mirrors do not show Correct answer.

Explanation

A blind spot is any area around the vehicle that cannot be seen in the mirrors. Large vehicles have big blind spots, so you must check them carefully before changing lanes.

Question 9Driving Safely

When making a right turn in a large vehicle, what should you do to avoid hitting a vehicle on your right?

  1. Swing wide to the left before turning right Correct answer.
  2. Use the right lane and turn sharply
  3. Turn from the far-left lane
  4. Speed up to complete the turn quickly

Explanation

Large vehicles need to swing wide to the left before a right turn to keep the rear wheels from cutting the corner and hitting a vehicle on the right. Turning too tightly causes off-tracking.

Question 10Driving Safely

What is 'off-tracking' in a commercial vehicle?

  1. The front wheels drifting during a turn
  2. The trailer swaying side to side
  3. The rear wheels following a shorter path than the front wheels Correct answer.
  4. The vehicle losing air pressure in a tire

Explanation

Off-tracking means the rear wheels of a long vehicle travel a shorter path than the front wheels during a turn. This is why large vehicles must swing wide to avoid hitting curbs or other vehicles.

Question 11Driving Safely

When should you downshift while driving a manual-transmission commercial vehicle?

  1. Only when the engine is idling
  2. While the vehicle is in neutral
  3. Only after you have already started braking hard
  4. Before entering a curve or going down a hill Correct answer.

Explanation

Downshift before a curve or a downgrade so you are in the correct gear and can use engine braking. Shifting after you are already in the curve or braking hard reduces control.

Question 12Driving Safely

You are driving down a long, steep downgrade. What is the correct way to control your speed?

  1. Use a low gear and apply the brakes as needed Correct answer.
  2. Turn off the engine to save fuel
  3. Shift to neutral and use the brakes
  4. Ride the brakes continuously

Explanation

On a steep downgrade, select a low gear so engine braking helps control speed, and use the brakes as needed. Riding the brakes can overheat them and cause brake fade.

Question 13Driving Safely

What is brake fade?

  1. A loss of braking power caused by overheated brakes Correct answer.
  2. The sound brakes make when wet
  3. A warning light on the dashboard
  4. A sudden increase in braking power

Explanation

Brake fade is the loss of braking power that occurs when brakes overheat, often from excessive use on downgrades. Using a lower gear helps prevent it.

Question 14Driving Safely

Before backing a commercial vehicle, what should you do if you cannot see behind the vehicle?

  1. Get out and check behind the vehicle Correct answer.
  2. Honk and back up quickly
  3. Rely on the backup alarm
  4. Back slowly using only the mirrors

Explanation

If you cannot see clearly behind the vehicle, get out and check before backing. Use a helper to guide you when possible. Never back when you cannot see.

Question 15Driving Safely

When is it safe to remove your seat belt while driving?

  1. Never while the vehicle is moving Correct answer.
  2. When adjusting the radio
  3. When driving in a parking lot
  4. When driving under 25 mph

Explanation

You must wear your seat belt whenever the vehicle is in motion. There is no speed or location exception for unbuckling while driving.

Question 16Driving Safely

What should you do when you see a hazard developing ahead while driving?

  1. Check your mirrors and slow down Correct answer.
  2. Sound your horn continuously
  3. Accelerate to pass the hazard quickly
  4. Change lanes without checking

Explanation

When a hazard develops, check your mirrors to know what is around you and slow down so you have time to react. Accelerating or changing lanes without checking increases risk.

Question 17Driving Safely

What is the correct action when a tire blows out at highway speed?

  1. Steer sharply to the shoulder
  2. Accelerate to stabilize the vehicle
  3. Brake hard immediately
  4. Hold the wheel firmly and slow gradually Correct answer.

Explanation

If a tire blows out, grip the wheel firmly, keep the vehicle straight, and slow down gradually before pulling off the road. Hard braking or sharp steering can cause a loss of control.

Question 18Driving Safely

How can you tell if you are driving too fast for conditions?

  1. Your headlights are on
  2. You are passing other vehicles
  3. Your engine is at low RPM
  4. You need to brake hard to stay in your lane on curves Correct answer.

Explanation

If you must brake hard to stay in your lane on curves or to react to traffic, you are driving too fast for conditions. Slow down so you can stay in control.

Question 19Driving Safely

What is the purpose of a pre-trip inspection?

  1. To check the vehicle for safety defects before driving Correct answer.
  2. To refuel the vehicle
  3. To record your hours of service
  4. To plan your route

Explanation

A pre-trip inspection is done to find safety defects before you drive, such as bad tires, brakes, or lights. Catching problems early prevents breakdowns and crashes.

Question 20Driving Safely

When driving in fog, which lights should you use?

  1. Four-way flashers while moving
  2. Parking lights only
  3. High-beam headlights
  4. Low-beam headlights Correct answer.

Explanation

Use low-beam headlights in fog because high beams reflect off the fog and reduce visibility. Low beams direct light down toward the road.

Question 21Driving Safely

What is the safest way to handle a curve in a commercial vehicle?

  1. Slow down before the curve and accelerate gently through it Correct answer.
  2. Brake hard while in the curve
  3. Coast through the curve in neutral
  4. Accelerate into the curve

Explanation

Slow down before entering the curve, then accelerate gently as you come out of it. Braking hard in a curve can cause a skid or rollover.

Question 22Driving Safely

What should you do if your vehicle starts to hydroplane on a wet road?

  1. Ease off the accelerator and avoid hard braking Correct answer.
  2. Turn the wheel quickly side to side
  3. Brake hard and steer sharply
  4. Accelerate to regain traction

Explanation

When hydroplaning, ease off the accelerator and let the vehicle slow gradually without hard braking or steering. This allows the tires to regain contact with the road.

Question 23Driving Safely

How does the weight of a load affect your stopping distance?

  1. A heavier load shortens stopping distance
  2. Weight has no effect on stopping distance
  3. A heavier load increases stopping distance Correct answer.
  4. Only the trailer weight matters

Explanation

A heavier load increases the vehicle's momentum, so it takes longer to stop. You must allow more following distance and brake earlier when carrying a heavy load.

Question 24Driving Safely

What is the proper way to use your horn in a commercial vehicle?

  1. To signal a turn
  2. To warn others of a hazard Correct answer.
  3. To greet other drivers
  4. To express frustration in traffic

Explanation

Use your horn only to warn others of a hazard. Using it for frustration, greetings, or signaling a turn is improper and can confuse other drivers.

Question 25Driving Safely

You are approaching a railroad crossing with no gates or lights. What should you do?

  1. Honk and proceed without slowing
  2. Slow down, look and listen, and be ready to stop Correct answer.
  3. Speed up to cross quickly
  4. Stop only if you see a train

Explanation

At a crossing without gates or lights, slow down, look both ways, listen, and be prepared to stop. Trains cannot stop quickly, so you must yield.

Question 26Driving Safely

What is the first thing you should do when you are involved in a collision?

  1. Exchange insurance information with the other driver.
  2. Drive to the nearest police station.
  3. Stop and check for injuries. Correct answer.
  4. Move your vehicle off the road if it is safe.

Explanation

After a collision, you must stop immediately and check for injuries. Moving the vehicle or exchanging information comes later, and leaving the scene is illegal.

Question 27Driving Safely

When driving at night, you should dim your high beams when you are within what distance of an oncoming vehicle?

  1. 200 feet
  2. 500 feet Correct answer.
  3. 300 feet
  4. 1,000 feet

Explanation

You must dim your high beams within 500 feet of an oncoming vehicle to avoid blinding the other driver. This is a standard rule in most states.

Question 28Driving Safely

What does a flashing yellow traffic signal mean?

  1. Stop and wait for a green light.
  2. Yield to traffic on the right only.
  3. The signal is broken; treat it as a four-way stop.
  4. Slow down and proceed with caution. Correct answer.

Explanation

A flashing yellow signal means you should slow down and proceed carefully, yielding to pedestrians and other traffic as needed. It does not require a full stop.

Question 29Driving Safely

When you are driving and a front tire suddenly goes flat, what is the best way to handle it?

  1. Accelerate to maintain control.
  2. Brake hard immediately to stop as quickly as possible.
  3. Hold the steering wheel firmly and steer straight ahead while slowing down. Correct answer.
  4. Turn the steering wheel sharply to the shoulder.

Explanation

A front tire blowout can pull the vehicle to one side. Hold the wheel firmly, keep the vehicle straight, and slow down gradually before pulling off the road.

Question 30Driving Safely

What is the purpose of the retarder on a heavy commercial vehicle?

  1. To improve fuel economy during acceleration.
  2. To increase engine power for climbing hills.
  3. To help slow the vehicle on downgrades without using the brakes. Correct answer.
  4. To reduce noise from the engine.

Explanation

A retarder is an auxiliary braking device that helps slow the vehicle, especially on long downgrades, reducing reliance on the service brakes and helping prevent brake fade.

Question 31Driving Safely

When you are driving a commercial vehicle, which of the following is a sign that you may be too tired to drive safely?

  1. You feel hungry.
  2. You are listening to the radio.
  3. You have difficulty keeping your eyes open. Correct answer.
  4. You have been driving for one hour.

Explanation

Difficulty keeping your eyes open is a clear sign of fatigue. Other signs include yawning repeatedly, drifting from your lane, and not remembering the last few miles driven.

Question 32Driving Safely

When you are driving in a construction zone, what should you do?

  1. Speed up to clear the zone quickly.
  2. Slow down and obey the posted speed limits and flaggers. Correct answer.
  3. Ignore flaggers if you do not see workers.
  4. Maintain your normal speed to avoid disrupting traffic flow.

Explanation

Construction zones often have reduced speed limits and flaggers directing traffic. You must slow down and follow their instructions, even if workers are not immediately visible.

Question 33Driving Safely

What is the recommended way to check your mirrors while driving?

  1. Glance at them quickly and frequently. Correct answer.
  2. Stare at them for several seconds to get a clear picture.
  3. Only check them when you are about to change lanes.
  4. Adjust them while driving to improve visibility.

Explanation

You should check your mirrors quickly and often to monitor traffic without becoming distracted. Staring or adjusting mirrors while driving is dangerous.

Question 34Driving Safely

When you are driving on a slippery road, what is the best way to maintain control?

  1. Brake hard to test traction.
  2. Accelerate quickly to get through slippery spots.
  3. Make smooth, gentle movements with the steering wheel and brakes. Correct answer.
  4. Turn the steering wheel sharply to feel the road.

Explanation

On slippery roads, smooth and gentle inputs help maintain traction and prevent skids. Sudden braking, acceleration, or steering can cause loss of control.

Question 35Driving Safely

What is the proper procedure for using a fire extinguisher on a vehicle fire?

  1. Use water first to cool the area.
  2. Aim at the top of the flames.
  3. Aim at the base of the fire and use a sweeping motion. Correct answer.
  4. Spray in short bursts while standing far away.

Explanation

To use a fire extinguisher, aim at the base of the fire and sweep side to side. This approach smothers the fuel source effectively.

Question 36Driving Safely

When you are driving and you encounter a strong crosswind, what should you do?

  1. Move to the left lane to avoid the wind.
  2. Reduce your speed and keep a firm grip on the steering wheel. Correct answer.
  3. Turn on your high beams for better visibility.
  4. Increase your speed to overcome the wind.

Explanation

Strong crosswinds can push your vehicle sideways. Reducing speed and holding the wheel firmly helps you maintain control.

Question 37Driving Safely

What should you do if your vehicle's brakes fail while you are driving?

  1. Steer into a ditch at high speed.
  2. Turn off the engine immediately.
  3. Downshift and use the parking brake gradually. Correct answer.
  4. Pump the accelerator to build pressure.

Explanation

If brakes fail, downshift to a lower gear to use engine braking, and apply the parking brake gradually. Turning off the engine can lock the steering.

Question 38Driving Safely

When you are driving at night, what should you do if you are blinded by the headlights of an oncoming vehicle?

  1. Turn on your high beams to retaliate.
  2. Speed up to get past the vehicle quickly.
  3. Look toward the right edge of your lane and slow down. Correct answer.
  4. Close your eyes briefly until the vehicle passes.

Explanation

To avoid being blinded, look toward the right edge of your lane and slow down. This helps you maintain your lane position without staring into the glare.

Question 39Driving Safely

What is the correct way to use turn signals when changing lanes?

  1. Signal only if other vehicles are present.
  2. Signal early and check mirrors before moving. Correct answer.
  3. Use hand signals instead of electrical signals.
  4. Signal only after you start moving.

Explanation

You should signal early to give other drivers warning, and always check your mirrors and blind spots before changing lanes.

Question 40Driving Safely

When you are driving a commercial vehicle, what is the proper way to handle a railroad crossing?

  1. Stop only if the lights are flashing.
  2. Stop, look, and listen before crossing. Correct answer.
  3. Slow down and proceed without stopping.
  4. Cross quickly without stopping if no train is visible.

Explanation

At railroad crossings, you should always stop, look both ways, and listen before proceeding, especially if you are driving a commercial vehicle.

Question 41Driving Safely

What is the recommended procedure for starting on a hill with a manual transmission?

  1. Shift into a higher gear to prevent rolling back.
  2. Release the clutch quickly while pressing the accelerator.
  3. Let the vehicle roll back slightly before accelerating.
  4. Use the parking brake to hold the vehicle while you release the clutch. Correct answer.

Explanation

Using the parking brake helps prevent rolling backward while you engage the clutch and accelerator. This technique is especially important for heavy vehicles.

Question 42Driving Safely

When you are driving and you see a school bus with its red lights flashing, what must you do?

  1. Pass on the left if no children are visible.
  2. Honk to warn the bus driver.
  3. Stop and wait until the lights stop flashing. Correct answer.
  4. Slow down and proceed with caution.

Explanation

Flashing red lights on a school bus mean you must stop and wait until the lights are turned off, regardless of whether you see children.

Question 43Driving Safely

What is the effect of using the engine brake (Jake brake) on a slippery road?

  1. It has no effect on traction.
  2. It can cause the drive wheels to skid. Correct answer.
  3. It reduces stopping distance.
  4. It improves traction.

Explanation

Engine brakes can cause the drive wheels to lose traction on slippery surfaces, leading to a skid. They should be used with caution in wet or icy conditions.

Question 44Driving Safely

When you are driving a commercial vehicle, how should you adjust your speed when entering a curve?

  1. Maintain speed and brake in the curve.
  2. Accelerate before the curve to maintain momentum.
  3. Brake hard in the curve to maintain control.
  4. Slow down before the curve and accelerate gently through it. Correct answer.

Explanation

The best practice is to slow down before entering the curve and then accelerate gently through it. Braking in a curve can cause skids or loss of control.

Question 45Driving Safely

What should you do if you are driving and you experience a blowout on a rear tire?

  1. Steer sharply to the shoulder.
  2. Brake hard immediately.
  3. Accelerate to stabilize the vehicle.
  4. Hold the steering wheel firmly and slow down gradually. Correct answer.

Explanation

A rear tire blowout can cause the vehicle to fishtail. Hold the wheel firmly, keep the vehicle straight, and slow down gradually before pulling over.

Question 46Driving Safely

When you are driving a commercial vehicle, what is the proper use of the parking brake?

  1. Use it to slow down on steep downgrades.
  2. Use it as a substitute for the service brakes.
  3. Use it to hold the vehicle when parked, not for normal stopping. Correct answer.
  4. Use it to stop the vehicle in an emergency only.

Explanation

The parking brake is designed to hold the vehicle in place when parked. It should not be used for normal stopping or as a primary brake on downgrades.

Question 47Driving Safely

What is the recommended action if you are driving and you encounter a vehicle coming toward you in your lane?

  1. Slow down, move to the right, and sound your horn. Correct answer.
  2. Maintain your speed and lane position.
  3. Move to the left to pass the vehicle.
  4. Speed up and flash your headlights.

Explanation

If a vehicle is approaching in your lane, slow down, steer to the right, and sound your horn to alert the driver. This gives you the best chance to avoid a collision.

Question 48Driving Safely

When you are driving a commercial vehicle, what is the effect of a heavy load on your vehicle's center of gravity?

  1. It shifts the center of gravity forward, improving traction.
  2. It has no effect on the center of gravity.
  3. It lowers the center of gravity, improving stability.
  4. It raises the center of gravity, increasing the risk of rollover. Correct answer.

Explanation

A heavy load, especially if it is high, raises the center of gravity and increases the likelihood of a rollover, particularly in curves or sudden maneuvers.

Question 49Driving Safely

What is the safest way to handle a situation where your vehicle's accelerator sticks?

  1. Pump the accelerator pedal rapidly.
  2. Turn off the engine immediately.
  3. Steer off the road and coast to a stop.
  4. Shift to neutral and brake to a stop. Correct answer.

Explanation

If the accelerator sticks, shift to neutral to disengage the engine, then brake to a stop. Turning off the engine can lock the steering and is not recommended.

Question 50Driving Safely

When you are driving a commercial vehicle, what is the recommended following distance for a vehicle traveling at 55 mph under ideal conditions?

  1. At least 3 seconds
  2. At least 5 seconds
  3. At least 7 seconds Correct answer.
  4. At least 4 seconds

Explanation

For a commercial vehicle traveling at 55 mph, a following distance of at least 7 seconds is recommended to allow for safe stopping. This accounts for the vehicle's weight and stopping distance.