CDL General Knowledge Test 1

Because of blind spots, you cannot see everything behind you. Using a helper is the most important safety rule for backing. Always agree on a hand signal for 'stop' before you begin.

Study focusUse safe backing, turning, and basic-control habits.

Common trapBacking without a helper or failing to stop when visibility is uncertain.

Good drivers look 12 to 15 seconds ahead. At highway speeds, this is about a quarter of a mile. This gives you time to adjust speed or change lanes to avoid hazards.

Study focusChoose safe speed, spacing, and visual search habits for commercial vehicles.

Common trapDriving at passenger-car speeds without accounting for weight, space, weather, or grade.

Your safe speed on a downgrade depends primarily on the total weight of the vehicle and cargo, the length and steepness of the grade, road conditions, and weather. Heavier vehicles require more braking power to counteract gravity.

Study focusUnderstand cargo weight, securement, and load safety responsibilities.

Common trapAssuming cargo safety is only the shipper or dispatcher responsibility.

Federal regulations require a minimum tread depth of 4/32 inch in every major groove on front (steering) tires. Other tires require at least 2/32 inch.

Study focusUse pre-trip inspection habits to identify unsafe vehicle-system defects before driving.

Common trapMemorizing a walk-around order without understanding which defects make the vehicle unsafe.

Use high beams whenever you can to see further ahead, provided it is safe and legal. You must dim them when within 500 feet of an oncoming vehicle or when following another vehicle within 500 feet.

Study focusApply core CDL safe-driving rules to common road and vehicle situations.

Common trapMemorizing rules without applying them to driving scenarios.

Alcohol first affects judgment and self-control. For commercial drivers, it is illegal to operate a CMV with a BAC of 0.04% or higher, not 0.08%.

Study focusUnderstand state-specific CDL requirements, handbook notes, and licensing context.

Common trapUsing generic CDL knowledge without checking state-specific requirements.

Hydroplaning occurs when water builds up in front of your tires, causing them to lift off the road surface. You lose steering and braking control. To recover, release the accelerator and do not brake hard.

Study focusUse pre-trip inspection habits to identify unsafe vehicle-system defects before driving.

Common trapMemorizing a walk-around order without understanding which defects make the vehicle unsafe.

When a tire blows out, grip the steering wheel firmly and stay off the brakes. Braking hard can cause a skid or loss of control. Let the vehicle slow down naturally before applying brakes gently.

Study focusUse pre-trip inspection habits to identify unsafe vehicle-system defects before driving.

Common trapMemorizing a walk-around order without understanding which defects make the vehicle unsafe.

You must inspect the cargo and its securing devices within the first 50 miles after beginning a trip. After that, inspect again after every break and after you have driven for 3 hours or 150 miles, whichever comes first.

Study focusUnderstand cargo weight, securement, and load safety responsibilities.

Common trapAssuming cargo safety is only the shipper or dispatcher responsibility.

Safety is the most important reason for a pre-trip inspection. Finding and fixing a defect before driving helps prevent breakdowns and crashes on the road.

Study focusUse pre-trip inspection habits to identify unsafe vehicle-system defects before driving.

Common trapMemorizing a walk-around order without understanding which defects make the vehicle unsafe.

Electrical fires require a B:C or A:B:C rated extinguisher. Using water or water-based foam on an electrical fire can result in a severe electric shock.

Study focusApply safe loading, separation, parking, routing, and emergency-response decisions for hazmat.

Common trapChoosing a convenient action instead of the action that protects people and isolates the hazard.

Engine retarders (Jake brakes) apply strong braking force to the drive wheels only. On slippery surfaces, this sudden braking force can cause the drive wheels to lose traction, leading to a dangerous skid.

Study focusRespond safely to hazards, emergencies, traction loss, and unsafe conditions.

Common trapReacting late or using sudden braking/steering when controlled action is safer.

The rule of thumb is 1 second of following distance for every 10 feet of vehicle length at speeds under 40 mph. For speeds over 40 mph, add 1 additional second. A 60-foot truck at 55 mph needs 7 seconds of space.

Study focusChoose safe speed, spacing, and visual search habits for commercial vehicles.

Common trapDriving at passenger-car speeds without accounting for weight, space, weather, or grade.

A broken exhaust system can allow deadly, odorless carbon monoxide gas to enter the cab, which can cause drowsiness, illness, or death to the driver.

Study focusRecognize placard, label, marking, and hazard-class requirements for hazmat loads.

Common trapFocusing only on the load name and ignoring placards, labels, and hazard class clues.

The first step in a vehicle fire is to get the vehicle off the road and stop in an open area, clear of buildings, trees, brush, and other vehicles to prevent the fire from spreading.

Study focusApply safe loading, separation, parking, routing, and emergency-response decisions for hazmat.

Common trapChoosing a convenient action instead of the action that protects people and isolates the hazard.

Eating, using a phone, or reading while driving are major physical and cognitive distractions that take your eyes, hands, and mind away from the critical task of driving.

Study focusRespond safely to hazards, emergencies, traction loss, and unsafe conditions.

Common trapReacting late or using sudden braking/steering when controlled action is safer.

If you are being tailgated, increase the space in front of your vehicle. This allows you to brake more smoothly and gradually, reducing the chance that the tailgater will crash into your rear.

Study focusChoose safe speed, spacing, and visual search habits for commercial vehicles.

Common trapDriving at passenger-car speeds without accounting for weight, space, weather, or grade.

You should brake to a safe speed before entering a curve. Once in the curve, maintain speed or accelerate slightly, as this helps stabilize the vehicle. Never brake hard in a curve.

Study focusChoose safe speed, spacing, and visual search habits for commercial vehicles.

Common trapDriving at passenger-car speeds without accounting for weight, space, weather, or grade.

Most serious skids result from driving too fast for road conditions, over-braking, over-steering, or over-accelerating. Speed is the primary factor in losing traction.

Study focusUse pre-trip inspection habits to identify unsafe vehicle-system defects before driving.

Common trapMemorizing a walk-around order without understanding which defects make the vehicle unsafe.

On a two-lane road carrying traffic in both directions, place warning devices within 10 feet of the front or rear corners, about 100 feet behind, and about 100 feet ahead of the vehicle.

Study focusRespond safely to hazards, emergencies, traction loss, and unsafe conditions.

Common trapReacting late or using sudden braking/steering when controlled action is safer.