57 General Knowledge Practice Questions & Answers

1. 1. Which list correctly names the three kinds of vehicle inspection a commercial driver is responsible for?

   • A.Roadside, terminal, and repair-shop inspections
   • B.Pre-trip, during-trip (en route), and after-trip (post-trip) inspections✓ Answer
   • C.Driver, mechanic, and state inspector inspections
   • D.Annual, quarterly, and monthly inspections

   Driver inspections are classified by when they happen: before the trip to find defects that could cause a breakdown or crash, en route (watching gauges and using look/listen/smell/feel, plus checking tires, brakes, lights, couplings and cargo at stops), and after the trip, which is written up in a report for each vehicle operated that day so the carrier can repair defects before the vehicle goes out again.

   Source: AAMVA Model CDL Manual §2.1; 49 CFR 396.11 and 396.13Report a problem with this question

2. 2. In Step 1 (Vehicle Overview) of the pre-trip inspection, what should you do with the previous driver's vehicle inspection report?

   • A.Send it to FMCSA before starting the trip
   • B.Throw it away, because only your own inspection counts
   • C.Review it, and sign it only if defects were reported and the carrier certified that they were repaired or that no repair was needed✓ Answer
   • D.Sign it right away so the vehicle can be released for service

   The overview step exists so a known defect is never driven away: the motor carrier must repair any item reported that affects safety and certify the repair (or certify that none was needed), and the driver's signature is required only when defects were reported. Signing a blank or uncertified report would defeat the paper trail that keeps unsafe vehicles off the road.

   Source: AAMVA Model CDL Manual §2.1.3, Step 1 (Vehicle Overview); 49 CFR 396.11(b), 396.13Report a problem with this question

3. 3. In the standard seven-step pre-trip inspection method, what do you do immediately after you turn off the engine and check the lights?

   • A.Do the walkaround inspection✓ Answer
   • B.Inspect the engine compartment
   • C.Start the engine and check the brake system
   • D.Check the signal lights

   The seven steps run in a fixed order for a reason: overview, engine compartment, start engine and check the cab, turn off the engine and check lights, walkaround, signal lights, then start the engine and check the brake system. Turning the low beams and four-way flashers on before shutting the engine off is what lets you walk the vehicle (Step 5) and see those lamps, reflectors, tires, wheels and couplings with the engine quiet.

   Source: AAMVA Model CDL Manual §2.1.3 (Seven-Step Inspection Method, Steps 4–5)Report a problem with this question

4. 4. What is the minimum tread depth required on the tires of the FRONT wheels of a commercial motor vehicle?

   • A.1/32 inch anywhere on the tire
   • B.4/32 inch in every major groove✓ Answer
   • C.2/32 inch in every major groove
   • D.6/32 inch in every major groove

   Front tires get the stricter 4/32-inch standard because a front-tire failure or loss of grip directly affects steering control, while all other tires must have at least 2/32 inch. Also check that no fabric shows through the tread or sidewall, that dual tires are not touching each other, and that radial and bias-ply tires are not mixed.

   Source: AAMVA Model CDL Manual §2.1.5 (Tires); 49 CFR 393.75(b), (c)Report a problem with this question

5. 5. A vehicle must be put out of service because of a leaf-spring defect when:

   • A.Any single leaf shows surface rust
   • B.The spring is covered with road grime
   • C.One-fourth or more of the leaves in a leaf spring are missing or broken✓ Answer
   • D.One-tenth or more of the leaves are missing or broken

   The suspension carries the load and holds the axles in place, so once one-fourth or more of the leaves are gone the spring can no longer control axle position or absorb load, and the vehicle is unsafe to move until repaired. Cracked or broken spring hangers, missing or broken torque rods and U-bolts, and leaking shock absorbers are inspected for the same reason.

   Source: AAMVA Model CDL Manual §2.1.5 (Suspension System Defects / out-of-service criteria)Report a problem with this question

6. 6. Besides spare electrical fuses and a properly charged and rated fire extinguisher, what emergency warning devices must a commercial vehicle carry?

   • A.Two red reflective triangles
   • B.One triangle and one flare
   • C.Three red reflective triangles, or six fusees, or three liquid-burning flares✓ Answer
   • D.Four orange traffic cones

   Three devices are required because a stopped vehicle must be marked at three points — close behind it and well ahead of and behind it — so approaching traffic gets warning in time to slow or change lanes. Spare fuses are not required if the vehicle uses circuit breakers.

   Source: AAMVA Model CDL Manual §2.1.2 (Emergency Equipment); 49 CFR 393.95Report a problem with this question

7. 7. What colors must clearance lights and reflectors be on a commercial vehicle?

   • A.White at the rear and red on the sides
   • B.Red at the rear and amber everywhere else✓ Answer
   • C.Amber at the rear and red everywhere else
   • D.Red at the front and amber at the rear

   Color coding tells other drivers which end of a large vehicle they are looking at in the dark: red always means you are seeing the rear, and amber marks the front and sides, so a wrong-colored or missing lamp can make a 70-foot rig unreadable at night. Brake lights, turn signals and four-way flashers must each be checked separately during the inspection.

   Source: AAMVA Model CDL Manual §11.1.2 (lights, reflectors and separate light checks); 49 CFR 393.11Report a problem with this question

8. 8. Why should you back toward the driver's side whenever you have a choice?

   • A.You can see much better on that side by looking out the window and using the driver's-side mirror✓ Answer
   • B.The blind spot on that side is larger, which gives you more room
   • C.It is required only when no helper is available
   • D.The trailer turns more sharply toward the left

   Backing is always dangerous because you cannot see everything behind you, so the rule is to avoid backing when you can and, when you must, keep the maneuver on the side where your own eyes work — the driver's side. Backing toward the right (blind) side hides people and objects behind the trailer entirely.

   Source: AAMVA Model CDL Manual §2.2.4 (Backing Safely)Report a problem with this question

9. 9. What is the safest procedure before and during backing?

   • A.Get out and walk around to look at the space first, back at idle speed, and if you use a helper, agree on hand signals — especially the signal for STOP — before you start✓ Answer
   • B.Have the helper stand directly behind the trailer so you can watch that person in the center mirror
   • C.Sound the horn continuously the whole time you are backing
   • D.Rely on the mirrors alone and back quickly so you clear traffic

   Walking the area is the only way to learn about low obstacles, holes, posts and people that no mirror will show, and idle speed keeps the vehicle slow enough to stop or correct drift with small steering movements. A helper belongs near the left rear where you can see them; standing directly behind the trailer puts the helper in the one place you cannot see and cannot avoid.

   Source: AAMVA Model CDL Manual §2.2.4 (Backing Safely — get out and inspect, use a helper, back slowly)Report a problem with this question

10. 10. When backing a tractor-trailer, to make the rear of the trailer move to the LEFT you should:

    • A.Hold the wheel straight and apply the trailer brake
    • B.Turn the steering wheel to the right✓ Answer
    • C.Turn the steering wheel to the left
    • D.Turn the wheel left, then quickly return it to center

    In reverse the trailer pivots at the fifth wheel and swings opposite to the steer axle, so you steer in the direction opposite to where you want the rear of the trailer to go, then follow the trailer with the tractor to straighten out. Because the trailer reacts slowly and then all at once, back at idle speed and correct any drift immediately with small movements.

    Source: AAMVA Model CDL Manual §2.2.4 (Backing with a trailer)Report a problem with this question

11. 11. When must a driver switch OFF an engine brake, exhaust brake, or other retarder?

    • A.On long, steep downgrades
    • B.When the road is wet, icy, or covered with snow✓ Answer
    • C.Whenever the service brakes are hot
    • D.Whenever the vehicle is fully loaded

    A retarder slows the vehicle through the drive wheels only, and on a slick surface that braking force easily exceeds the available traction, locking the drive wheels and starting a skid or jackknife. On dry roads retarders are useful precisely because they save wear on the service brakes.

    Source: AAMVA Model CDL Manual §2.3.5 (Retarders)Report a problem with this question

12. 12. Before you start down a steep grade, you should:

    • A.Wait until the vehicle picks up speed and then downshift
    • B.Stay in the highest gear the engine will pull
    • C.Shift into neutral so the engine is not strained
    • D.Shift into a low gear before the descent begins — normally a lower gear than you would need to climb the same hill✓ Answer

    Gravity keeps adding speed on a downgrade, and with modern engines you often cannot get back into a lower gear once the vehicle is rolling fast — you can be left with no engine braking at all. Coasting in neutral or with the clutch held in is both unsafe and illegal, because it removes engine braking and delays your ability to accelerate out of trouble.

    Source: AAMVA Model CDL Manual §2.3.3 (Shifting patterns / downshifting) and §2.16 (Mountain Driving)Report a problem with this question

13. 13. Which statement describes correct basic control of a heavy vehicle?

    • A.Steer with one hand at the top of the wheel so the other hand is free to shift
    • B.Speed up smoothly and gradually, hold the wheel firmly with both hands on opposite sides, and brake with steady pressure to a gradual stop✓ Answer
    • C.Accelerate hard so the drive wheels bite and get traction
    • D.Pump the brake pedal rapidly for every normal stop

    Rough acceleration can damage the coupling between tractor and trailer and will spin the drive wheels on a slippery surface, while both hands on opposite sides (roughly the 9 and 3 positions) keeps you from losing the wheel if a tire drops into a hole or hits a curb. With a manual transmission, push in the clutch as the engine gets close to idle so the engine does not stall at the stop.

    Source: AAMVA Model CDL Manual §2.2.1–2.2.3 (Accelerating, Steering, Stopping)Report a problem with this question

14. 14. At speeds BELOW 40 mph, what is the minimum following distance rule for a heavy vehicle?

    • A.One second for every 10 feet of vehicle length✓ Answer
    • B.Two seconds, no matter how long the vehicle is
    • C.One second for every 10 feet of vehicle length, plus 2 extra seconds
    • D.One second for every 20 feet of vehicle length

    The rule scales with length because a longer vehicle takes longer to get completely past a hazard and needs more distance to stop, and it scales with speed because everything happens faster: above 40 mph you add one more second. Measure it by counting the seconds between the moment the vehicle ahead passes a landmark and the moment you reach it.

    Source: AAMVA Model CDL Manual §2.7.1 (Space Ahead — following distance rule)Report a problem with this question

15. 15. You are driving a 50-foot combination vehicle at 50 mph on dry pavement. What is the minimum following distance you should keep?

    • A.6 seconds✓ Answer
    • B.7 seconds
    • C.5 seconds
    • D.4 seconds

    Fifty feet of vehicle gives 5 seconds at one second per 10 feet, and because 50 mph is above 40 mph you add one more second, for a total of 6. The extra second above 40 mph exists because both your reaction distance and your braking distance grow with speed.

    Source: AAMVA Model CDL Manual §2.7.1 (Space Ahead — following distance rule)Report a problem with this question

16. 16. Another driver is following you too closely (tailgating). What should you do?

    • A.Move into the left lane and stay there until the tailgater leaves
    • B.Speed up to open a gap between you and the tailgater
    • C.Increase your own following distance ahead so you can slow gradually, avoid quick lane changes, and let the tailgater get around you✓ Answer
    • D.Tap the brakes repeatedly to make the tailgater back off

    You cannot control the space behind you, but you can control the space in front: more room ahead lets you slow smoothly instead of braking hard, which is what would cause the tailgater to hit you. Speeding up just moves the problem to a higher speed, and brake-light tricks invite a rear-end collision.

    Source: AAMVA Model CDL Manual §2.7.2 (Space Behind)Report a problem with this question

17. 17. Which statement about overhead clearance is correct?

    • A.Overhead clearance only matters for flatbed loads
    • B.A loaded van trailer is taller than an empty one
    • C.Posted bridge and overpass heights are always accurate
    • D.An empty van trailer sits higher than a loaded one, and posted clearances can be wrong because repaving or packed snow raises the road surface✓ Answer

    Weight compresses the suspension and tires, so an empty trailer rides higher than the same trailer loaded — a route that cleared yesterday when loaded may not clear today when empty. Posted heights are not a guarantee either, because adding pavement layers or packed snow lowers the real clearance, so slow down and take another route if there is any doubt.

    Source: AAMVA Model CDL Manual §2.7.4 (Space Overhead)Report a problem with this question

18. 18. Total stopping distance for a commercial vehicle is the sum of:

    • A.Perception distance + braking distance only
    • B.Following distance + braking distance
    • C.Reaction distance + braking distance only
    • D.Perception distance + reaction distance + braking distance✓ Answer

    Two of the three parts happen before the brakes ever apply: perception distance is what you travel while your brain recognizes the hazard (about 1-3/4 seconds for an alert driver) and reaction distance is what you travel while your foot moves to the pedal (about 3/4 to 1 second). Ignoring those two is why drivers badly underestimate how much room a heavy vehicle needs.

    Source: AAMVA Model CDL Manual §2.6.1 (Stopping Distance)Report a problem with this question

19. 19. At about 55 mph on dry pavement with good brakes, the total stopping distance of a loaded heavy vehicle is closest to:

    • A.About 216 feet
    • B.About 300 feet
    • C.About 419 feet — more than the length of a football field✓ Answer
    • D.About 150 feet

    The three parts add up: roughly 142 feet of perception distance, 61 feet of reaction distance, and about 216 feet of braking distance. Because the number is longer than a football field, any gap that merely 'looks big enough' at highway speed usually is not.

    Source: AAMVA Model CDL Manual §2.6.1 (Stopping Distance — 142 + 61 + 216 ≈ 419 feet at 55 mph)Report a problem with this question

20. 20. If you double your speed from 20 mph to 40 mph, braking distance and force of impact become about:

    • A.Three times as great
    • B.Twice as great
    • C.Unchanged, because vehicle weight matters more than speed
    • D.Four times as great✓ Answer

    Kinetic energy rises with the square of speed, so doubling speed multiplies both braking distance and impact force by about four, and tripling from 20 to 60 mph multiplies them by about nine. This is why a small speed reduction produces a surprisingly large safety gain.

    Source: AAMVA Model CDL Manual §2.6.1 (Effect of Speed on Stopping Distance)Report a problem with this question

21. 21. Compared with the same truck fully loaded, an EMPTY truck:

    • A.Cannot lock up its wheels under hard braking
    • B.Always stops in a shorter distance because it weighs less
    • C.Has exactly the same stopping distance
    • D.Usually needs a GREATER stopping distance, because there is less weight pressing the tires onto the road and therefore less traction✓ Answer

    Brakes, tires and suspension on a heavy vehicle are designed to work best when the vehicle is loaded; empty, the tires have little weight on them, so the wheels lock and bounce and the vehicle slides farther. The extra braking capacity does not help once the tires stop gripping.

    Source: AAMVA Model CDL Manual §2.6.2 (Matching Speed to the Road Surface / empty trucks)Report a problem with this question

22. 22. Starting from a safe dry-road speed, about how much should you reduce speed on a wet road, and then on packed snow?

    • A.About one-tenth on wet, about one-third on packed snow
    • B.About one-half on wet, about one-third on packed snow
    • C.About one-third on wet, about one-half on packed snow✓ Answer
    • D.No reduction on wet; about one-quarter on packed snow

    A wet surface can double your stopping distance, so cutting speed by roughly a third (for example, 55 mph down to about 35 mph) restores the margin you had when dry; packed snow cuts traction far more, calling for about half. On ice you must slow to a crawl, and remember that melting (wet) ice is more slippery than ice that is dry and cold.

    Source: AAMVA Model CDL Manual §2.6.3 (Speed and Slippery Surfaces)Report a problem with this question

23. 23. Hydroplaning can begin at speeds as low as:

    • A.50 mph
    • B.30 mph, when there is a lot of water on the road✓ Answer
    • C.Only above 70 mph
    • D.65 mph

    Hydroplaning happens when the tires cannot push water aside fast enough and ride up on a film of water instead of touching pavement, which needs only standing water plus enough speed — as little as 30 mph, and less if tire pressure is low or tread is worn. If it happens, release the accelerator and push in the clutch to let the wheels slow and regain contact rather than braking hard.

    Source: AAMVA Model CDL Manual §2.6.3 (Hydroplaning)Report a problem with this question

24. 24. What is an escape ramp on a mountain grade designed to do?

    • A.Give slow vehicles a place to pull over and let traffic pass
    • B.Provide a place to inspect brakes at the bottom of the hill
    • C.Stop a runaway vehicle using a long bed of loose, soft material — sometimes on an upgrade — without injuring the occupants✓ Answer
    • D.Let drivers cool overheated brakes with water

    Escape ramps work by absorbing the vehicle's energy gradually in gravel or sand instead of in a crash, which is why they stop a truck whose brakes have faded or failed without killing the occupants. Because you may have only seconds to use one, note where they are before you start down an unfamiliar grade.

    Source: AAMVA Model CDL Manual §2.16 (Mountain Driving — Escape Ramps)Report a problem with this question

25. 25. Convex ("fisheye", "spot" or "bug-eye") mirrors:

    • A.Show a wider field of view, but make objects look smaller and farther away than they really are✓ Answer
    • B.Show a narrower area, but at true size and distance
    • C.Make objects look larger and closer than they really are
    • D.Eliminate all blind spots around the vehicle

    The curved surface squeezes a wide area into a small image, and that compression is exactly what makes a car alongside you look smaller and more distant than it is — so a vehicle that appears to have room to spare may actually be beside your trailer. Use the convex mirror to know a vehicle is there, and the flat mirror plus a head check to judge distance before changing lanes.

    Source: AAMVA Model CDL Manual §2.4.2 (Mirror Use — convex mirrors)Report a problem with this question

26. 26. How far ahead should a commercial driver normally be looking?

    • A.About 5 seconds ahead
    • B.About 2 to 3 seconds ahead
    • C.Only as far as the headlights reach, at any speed
    • D.12 to 15 seconds ahead — roughly one city block at low speed and about a quarter of a mile at highway speed✓ Answer

    A heavy vehicle cannot stop or change lanes quickly, so you need to see a problem 12 to 15 seconds before you reach it in order to slow smoothly or change lanes without an emergency maneuver. Looking only a few seconds ahead means you find out about a hazard after your options have already closed.

    Source: AAMVA Model CDL Manual §2.4.1 (Seeing — Looking Ahead)Report a problem with this question

27. 27. Which statement about using turn signals is correct?

    • A.Cancel the signal partway through the turn so other drivers know you are finishing
    • B.Signal early, keep signaling all the way through the turn with both hands on the wheel, and cancel the signal afterward if it does not cancel itself✓ Answer
    • C.Flashing your turn signal is the accepted way to tell a driver behind you that it is safe to pass
    • D.Signal only after you have begun the turn, so other drivers are not confused

    Signals only work if they are given early enough for others to act on and stay on until the maneuver is complete; cancelling early tells traffic you have finished a turn you are still making. Never use a signal to wave another driver past, because you cannot see or judge the whole situation for them and you can be held responsible if a crash results.

    Source: AAMVA Model CDL Manual §2.5.1 (Communicating — Signal Your Intentions)Report a problem with this question

28. 28. You have stopped on the shoulder of a two-lane road that carries traffic in both directions. Where must the warning devices be placed?

    • A.At 10 feet, 100 feet and 200 feet, all placed behind the vehicle
    • B.One device at the rear only; the four-way flashers take care of the rest
    • C.Within 10 feet of the rear of the vehicle, about 100 feet behind it, and about 100 feet ahead of it, on the shoulder or in the lane, and put out within 10 minutes✓ Answer
    • D.All three within 50 feet of the rear of the vehicle

    On an undivided two-way road, traffic can reach you from both directions, so one device must warn drivers coming from behind and one must warn drivers coming toward you from ahead. The 10/100/200-foot pattern, all toward approaching traffic, applies on a one-way or divided highway; in either case, if a hill or curve blocks the view, move the rear device back beyond the obstruction up to 500 feet, and get the devices out within 10 minutes of stopping.

    Source: AAMVA Model CDL Manual §2.5.2 (Warning Devices for Parked Vehicles); 49 CFR 392.22(b)Report a problem with this question

29. 29. Under the CDL manual's definition, what turns a road hazard into an emergency?

    • A.It appears within your stopping distance at highway speed
    • B.Another driver warns you about it with a horn or headlights
    • C.It involves another vehicle rather than a road condition
    • D.It begins to require you to take immediate action to avoid a crash✓ Answer

    A hazard is any road condition or road user that is a possible danger, and it stays only a hazard while you still have time to plan. It becomes an emergency the moment it forces immediate action, which is why you look far ahead and choose an escape route while the situation is still just a hazard.

    Source: AAMVA Model CDL Manual Sec. 2.8.1 (Seeing Hazards)Report a problem with this question

30. 30. The air temperature is near freezing and the pavement looks merely wet. Which part of your route is most likely to be icy?

    • A.Freshly repaved asphalt
    • B.Uphill grades
    • C.Bridges and overpasses✓ Answer
    • D.Long straight stretches in full sun

    Bridges and overpasses lose heat from above and below because air circulates underneath them, so they freeze before the surrounding roadway does. Shaded areas stay icy for the same reason, and black ice can look exactly like plain wet pavement, so check for ice building up on your mirror arms or antenna when you are unsure.

    Source: AAMVA Model CDL Manual Sec. 2.13 (Driving in Winter); Sec. 2.6.2 (Slippery Surfaces)Report a problem with this question

31. 31. You are driving through standing water when the steering suddenly feels light and the vehicle stops responding. What should you do?

    • A.Steer sharply toward the shoulder
    • B.Brake hard to break through the film of water
    • C.Release the accelerator and push in the clutch✓ Answer
    • D.Accelerate to push the water out from under the tires

    In hydroplaning the tires ride on a film of water and lose contact with the road, so braking or steering input has nothing to grip and only makes matters worse. Releasing the accelerator and pushing in the clutch lets the vehicle slow on its own until the tires touch pavement again. Hydroplaning can begin at speeds as low as 30 mph when there is a lot of water, and low tire pressure or worn tread makes it more likely.

    Source: AAMVA Model CDL Manual Sec. 2.6.2 (Hydroplaning)Report a problem with this question

32. 32. If you must drive through dense fog, which lights should you use?

    • A.Parking lights only
    • B.High beams, to see as far ahead as possible
    • C.Four-way flashers instead of headlights
    • D.Low beams, plus fog lights if the vehicle has them✓ Answer

    High beams reflect off the water droplets suspended in fog and bounce glare straight back at the driver, so they actually reduce what you can see; low beams throw light lower and cut that glare. The safest choice of all is still to delay the trip or pull off at a safe place until the fog lifts.

    Source: AAMVA Model CDL Manual Sec. 2.12 (Driving in Fog)Report a problem with this question

33. 33. When should you shift into a lower gear for a long, steep downgrade?

    • A.Before you start down the grade✓ Answer
    • B.After the vehicle has picked up speed, so you can match engine rpm
    • C.Only if the brakes begin to fade
    • D.At the bottom, so you can accelerate away

    Gravity builds speed fast on a downgrade, and on a modern truck that has already gained speed you may not be able to get it into a lower gear at all, leaving only the service brakes, which overheat and fade. Select a safe speed and a low gear at the top, then hold that speed with short, firm brake applications of about three seconds each.

    Source: AAMVA Model CDL Manual Sec. 2.16 (Mountain Driving)Report a problem with this question

34. 34. During a stop in very hot weather you find one tire much hotter than the others, with pressure above normal. What should you do?

    • A.Bleed air out until the pressure returns to the normal cold setting
    • B.Stop driving until the tire cools, and check the tires more often✓ Answer
    • C.Nothing, because pressure always rises in heat, so keep going at the same speed
    • D.Pour water over the tire to cool it quickly

    Pressure rising with heat is normal, but a tire that is unusually hot is warning you of a possible blowout or even a tire fire. Letting air out leaves that tire underinflated once it cools, and an underinflated tire flexes more and runs even hotter, so the correct response is to let it cool, slow down, and inspect the tires often in extreme heat.

    Source: AAMVA Model CDL Manual Sec. 2.14 (Driving in Very Hot Weather)Report a problem with this question

35. 35. Which of these vehicles must stop at every railroad crossing, whether or not a train is coming?

    • A.Any vehicle with a GVWR over 26,001 pounds
    • B.Any combination vehicle pulling a trailer
    • C.Any vehicle equipped with air brakes
    • D.A truck required to display hazardous materials placards✓ Answer

    Placarded hazardous materials vehicles, buses carrying passengers, and school buses must always stop 15 to 50 feet from the nearest rail, look and listen in both directions, and then cross without shifting gears. The rule exists because of what those loads and occupants would mean in a collision, not because of a vehicle's weight or brake system.

    Source: AAMVA Model CDL Manual Sec. 2.15 (Railroad-Highway Crossings); 49 CFR 392.10Report a problem with this question

36. 36. You are approaching a railroad crossing and traffic is backed up on the far side. What should you do?

    • A.Cross in your lowest gear and stop on the tracks if traffic has not moved
    • B.Pull onto the tracks and wait there for the traffic ahead to move
    • C.Stay off the tracks until you are sure you can drive all the way across without stopping✓ Answer
    • D.Shift into a lower gear once you are on the tracks so you can speed up

    A tractor-trailer needs roughly 14 seconds to clear a single track and about 15 seconds for a double track, and you cannot count on backing up or squeezing into a gap. Never start across without room for the entire vehicle on the far side, and never shift gears on the tracks, since a stall there is a leading cause of truck-train collisions.

    Source: AAMVA Model CDL Manual Sec. 2.15 (Railroad-Highway Crossings)Report a problem with this question

37. 37. Your brakes have failed on a long mountain downgrade and a sign shows an escape ramp ahead. What should you do?

    • A.Keep trying to hold your speed with the brakes and pass the ramp if the road ahead looks clear
    • B.Shut off the engine to slow the vehicle down
    • C.Take the escape ramp✓ Answer
    • D.Sideswipe the guardrail to scrub off speed

    Escape ramps use soft gravel or an upgrade to stop a runaway vehicle with little damage to the truck and none to anyone else, and signs announce them well before the ramp itself. Speed only builds the longer you stay on the grade, so commit immediately; delay can put the ramp out of reach.

    Source: AAMVA Model CDL Manual Sec. 2.16 (Escape Ramps); Sec. 2.17.4 (Brake Failure)Report a problem with this question

38. 38. You hear a loud bang and the steering suddenly becomes very hard. What should you do first?

    • A.Brake hard immediately to stop as quickly as possible
    • B.Hold the wheel firmly with both hands and stay off the brake until the vehicle slows✓ Answer
    • C.Downshift quickly through the gears to slow the vehicle
    • D.Steer onto the shoulder at once and set the parking brake

    Heavy steering points to a failed front tire, and braking on a blown tire pulls the vehicle hard toward the failure and can cost you control. Hold the wheel firmly, let the vehicle slow on its own, then brake gently and pull well off the road; afterward check every tire, because a failed inside dual may give no other sign.

    Source: AAMVA Model CDL Manual Sec. 2.17.5 (Tire Failure)Report a problem with this question

39. 39. The rear of your trailer starts to swing out because the rear wheels locked up while braking. What is the correct response?

    • A.Brake harder so the front wheels lock too
    • B.Hold the wheel straight and keep steady pressure on the brakes
    • C.Accelerate to pull the trailer back into line
    • D.Stop braking, then counter-steer as the vehicle swings back into line✓ Answer

    Locked wheels have less traction than rolling wheels, so the rear end slides sideways to catch up with the front, which is how a jackknife starts. Releasing the brakes lets the rear wheels roll and grip again, and because the rear then swings back quickly you must counter-steer or the vehicle will skid the other way.

    Source: AAMVA Model CDL Manual Sec. 2.19.2 (Drive-Wheel Braking Skids)Report a problem with this question

40. 40. In a front-wheel skid the vehicle keeps going straight no matter how you turn the steering wheel. What is the only cure?

    • A.Counter-steer hard in the opposite direction
    • B.Stop braking and steering so hard, and let the vehicle slow down✓ Answer
    • C.Accelerate to put more weight on the front axle
    • D.Apply the trailer hand valve

    In a front-wheel skid the steering tires have already lost their grip, so more steering input does nothing and more braking only keeps them from rolling. Easing off the brake and straightening the wheel lets speed bleed off until the front tires regain traction. Front-wheel skids come mostly from driving too fast for conditions, worn front tread, or too little weight on the front axle.

    Source: AAMVA Model CDL Manual Sec. 2.19.2 (Front-Wheel Skids)Report a problem with this question

41. 41. A car ahead stops suddenly and you do not have room to stop. Which statement is true?

    • A.You should always steer to the left, into the oncoming lane
    • B.You should brake hard while you steer around the obstacle
    • C.You can usually steer around an obstacle in less distance than it takes to stop✓ Answer
    • D.Stopping is always the safest response to an emergency

    At highway speed a heavy vehicle can change direction in less distance than it needs to stop, so steering is often the better escape, though top-heavy rigs and multi-trailer combinations may roll. Keep both hands on the wheel, do not brake while turning because that can lock the wheels, turn no more than needed, and be ready to counter-steer at once. If both sides are blocked, or an oncoming driver drifts into your lane, steer right so you do not force anyone into oncoming traffic.

    Source: AAMVA Model CDL Manual Sec. 2.17.2 (Evasive Steering)Report a problem with this question

42. 42. A load of lumber is burning and the only extinguisher on board is rated B:C. What does that rating mean here?

    • A.It will work, because Class B covers ordinary combustibles
    • B.It will not work: a B:C unit is rated for burning liquids and electrical fires, not wood✓ Answer
    • C.B:C means it is rated for every class of fire
    • D.It will work on wood only after you soak the load with water

    Class A fires are wood, paper, cloth, and other ordinary combustibles; Class B is gasoline, oil, grease, and other flammable liquids; Class C is electrical. A B:C extinguisher carries no Class A rating, so it will not put out burning lumber; only an A:B:C unit covers all three classes.

    Source: AAMVA Model CDL Manual Sec. 2.21.3 (Fire Extinguishers)Report a problem with this question

43. 43. When you use a fire extinguisher on a vehicle fire, you should:

    • A.Empty the extinguisher in one long burst and then leave the scene
    • B.Stand downwind so the wind carries the agent into the fire
    • C.Get as close as you can and aim at the top of the flames
    • D.Stay as far back as the extinguisher will reach, stand upwind, and aim at the base of the fire✓ Answer

    A fire is fed at its source, so the agent has to reach the base of the flames rather than the flame tips. Standing upwind and as far back as the extinguisher's range allows keeps the agent moving toward the fire and the heat and smoke away from you, and you keep applying it until the material has cooled, because no visible flame does not mean it cannot re-ignite.

    Source: AAMVA Model CDL Manual Sec. 2.21.3 (Fighting Fires)Report a problem with this question

44. 44. Smoke is coming from the cargo area of your loaded van trailer. After stopping in an open area away from other vehicles, what should you do about the trailer doors?

    • A.Open just one door, to let the smoke out
    • B.Open them right away so you can get to the burning cargo
    • C.Open them and keep driving so airflow smothers the fire
    • D.Keep them closed and let the fire department open them✓ Answer

    Opening the doors gives the fire a fresh supply of oxygen and can turn a smoldering load into a fully involved fire in seconds. Keep the doors shut, park well away from buildings, trees, brush, and other vehicles, never pull into a service station, and call emergency services.

    Source: AAMVA Model CDL Manual Sec. 2.21.3 (Fighting Fires)Report a problem with this question

45. 45. You must stop on the shoulder of a divided four-lane highway. Where do the three reflective triangles go?

    • A.50 feet, 150 feet, and 250 feet behind the vehicle
    • B.All three within 10 feet of the rear of the vehicle
    • C.10 feet, 100 feet, and 200 feet back toward approaching traffic✓ Answer
    • D.Within 10 feet of the vehicle, 100 feet behind it, and 100 feet ahead of it

    On a one-way or divided highway all traffic approaches from one direction, so the devices go 10, 100, and 200 feet back toward that traffic to give approaching drivers progressively earlier warning. On a two-lane two-way road the pattern is different: within 10 feet of the vehicle, 100 feet behind, and 100 feet ahead. In either case the devices must be out within 10 minutes of stopping.

    Source: 49 CFR 392.22(b); AAMVA Model CDL Manual Sec. 2.5.2 (Warning Devices)Report a problem with this question

46. 46. You are first on the scene of a crash. What is the correct order of the three basic steps?

    • A.Care for the injured, protect the area, notify authorities
    • B.Protect the area, notify authorities, care for the injured✓ Answer
    • C.Notify authorities, protect the area, care for the injured
    • D.Protect the area, care for the injured, notify authorities

    Protecting the area first keeps a second crash from injuring you and the people already hurt: park away from the scene so emergency vehicles can get in, turn on your four-way flashers, and set out warning devices. Notifying authorities next gets trained help moving while you give basic care, such as stopping heavy bleeding with direct pressure and keeping the injured warm; do not move a badly injured person unless fire or traffic makes it necessary.

    Source: AAMVA Model CDL Manual Sec. 2.20 (Accident Procedures)Report a problem with this question

47. 47. What does GVWR mean?

    • A.The combined weight of the power unit, the trailer, and the cargo
    • B.The weight transmitted to the ground by one set of axles
    • C.The actual weight of a loaded vehicle as measured on a scale
    • D.The maximum loaded weight the manufacturer specifies for a single vehicle✓ Answer

    GVWR is a rating set by the manufacturer, not a measurement: it is the most a single vehicle plus its load is designed to weigh. The measured scale weight of that vehicle is GVW; the manufacturer's rating for a combination is GCWR, its actual weight is GCW, and the load carried by one axle or axle set is the axle weight.

    Source: AAMVA Model CDL Manual Sec. 3.2.1 (Definitions You Should Know)Report a problem with this question

48. 48. Under a bridge formula, what happens to the maximum weight allowed on a group of axles as those axles are placed closer together?

    • A.More weight is allowed
    • B.The allowed weight is unchanged as long as no single axle is overloaded
    • C.Less weight is allowed✓ Answer
    • D.The formula no longer applies; only tire load limits matter

    A bridge formula protects bridge and pavement structures by spreading weight over a longer span: axles bunched close together concentrate the load on a short section of the structure, so less total weight is permitted. Spreading the same axles farther apart distributes the load and allows more weight.

    Source: Federal Bridge Formula, 23 U.S.C. 127 / 23 CFR 658; AAMVA Model CDL Manual Sec. 3.2.2 (Legal Weight Limits)Report a problem with this question

49. 49. You are loading heavy crates and lighter boxes into a trailer. How should the weight be arranged?

    • A.Put the heaviest crates on the bottom, under the lighter cargo✓ Answer
    • B.Put all of the heavy weight behind the rear axle
    • C.Put all of the heavy weight over the steering axle
    • D.Put the heaviest crates on top so the lighter cargo is not crushed

    Stacking heavy cargo high raises the vehicle's center of gravity and makes a rollover much more likely in a curve or a sudden swerve. Keeping the heaviest items low and spread out keeps the center of gravity low; the load must also be distributed so no axle is overloaded, since too much weight on the steering axle makes steering hard and too little makes the steering axle unable to steer safely.

    Source: AAMVA Model CDL Manual Sec. 3.2.3 (Center of Gravity / Balancing Weight)Report a problem with this question

50. 50. How many tiedowns does a 6-foot-long article of cargo need on a flatbed?

    • A.One
    • B.None, as long as it is blocked against the header board
    • C.Three
    • D.Two✓ Answer

    The manual's rule is at least one tiedown for every 10 feet of cargo and, no matter how short the article is, never fewer than two. A single tiedown lets the load pivot around it, so two is the floor: a 20-foot article also takes 2, and a 25-foot article takes 3.

    Source: AAMVA Model CDL Manual Sec. 3.3 (Securing Cargo); 49 CFR 393.110Report a problem with this question

51. 51. Federal cargo securement rules require the aggregate working load limit of the tiedowns to be at least how much of the weight of the cargo secured?

    • A.One-half of the cargo weight✓ Answer
    • B.One-quarter of the cargo weight
    • C.Equal to the cargo weight
    • D.Twice the cargo weight

    The aggregate working load limit of the securement system must be at least one-half the weight of the article or group of articles being secured. Working load limit is a safe working rating well below breaking strength, and the rating of any single tiedown is only as high as its weakest component, including the tensioner and the anchor point on the vehicle.

    Source: 49 CFR 393.106(d); AAMVA Model CDL Manual Sec. 3.3 (Securing Cargo)Report a problem with this question

52. 52. How soon after beginning a trip must you inspect your cargo and its securing devices?

    • A.At the end of the driving day
    • B.After the first 3 hours of driving
    • C.Within the first 50 miles✓ Answer
    • D.Within the first 150 miles

    Cargo settles and tiedowns lose tension as soon as the vehicle starts moving, so the first check comes early, within the first 50 miles, and you make any needed adjustments then. After that, re-examine the load every 3 hours or 150 miles of driving, whichever comes first, and after every break. Whether or not you loaded it, you are responsible for inspecting the cargo, recognizing overloads and poor balance, securing it so it does not block your view, and making sure it does not block access to your emergency equipment.

    Source: 49 CFR 392.9(b)(3); AAMVA Model CDL Manual Sec. 3.1 (Inspecting Cargo)Report a problem with this question

53. 53. A driver is found to have a blood alcohol concentration of 0.02 while operating a CMV. Under federal rules, what happens?

    • A.He is placed out of service for 24 hours✓ Answer
    • B.He is placed out of service for 10 hours
    • C.He is disqualified for one year for driving under the influence
    • D.Nothing, because the CMV limit is 0.04

    It is illegal to operate a commercial motor vehicle at 0.04 BAC or more, but any detectable alcohol below that level still puts the driver out of service for 24 hours. Federal rules also prohibit using alcohol, or being under its influence, within 4 hours before going on duty or driving.

    Source: 49 CFR 392.5(a) and 392.5(g); 49 CFR 383.51Report a problem with this question

54. 54. A driver refuses to submit to required alcohol testing after being stopped in a CMV. What is the minimum consequence for a first offense?

    • A.A 60-day disqualification
    • B.A warning letter placed in the driver qualification file
    • C.A disqualification of at least one year✓ Answer
    • D.No penalty, because testing requires the driver's consent

    Operating a CMV is legally treated as implied consent to alcohol testing, so a refusal carries the same penalty as a positive test: disqualification for at least one year on a first offense, three years if the driver was operating a placarded hazardous materials vehicle, and a lifetime disqualification for a second offense.

    Source: 49 CFR 383.51(b), Table 1 (refusal to submit to testing)Report a problem with this question

55. 55. Under the federal hours-of-service rules for property-carrying drivers, when is a 30-minute break required?

    • A.After 11 hours of driving
    • B.After 8 cumulative hours of driving time✓ Answer
    • C.Every 4 hours, no matter how much of that time was spent driving
    • D.After 8 consecutive hours on duty

    The break is tied to driving time, not on-duty time: once a driver accumulates 8 hours of driving, no further driving is allowed until an interruption of at least 30 consecutive minutes. That interruption can be off-duty, sleeper-berth, or on-duty-not-driving time, so a 30-minute wait at a loading dock satisfies it.

    Source: 49 CFR 395.3(a)(3)(ii)Report a problem with this question

56. 56. Which license class is required to drive a combination with a GCWR of 60,000 pounds in which the towed unit is rated over 10,000 pounds?

    • A.Class B
    • B.Class A✓ Answer
    • C.Class C
    • D.Class B with a doubles/triples endorsement

    Class A covers any combination with a GCWR of 26,001 pounds or more where the towed unit or units are rated over 10,000 pounds, which is exactly this vehicle. Class B is a single vehicle of 26,001 pounds or more, which may tow a unit rated at 10,000 pounds or less, and Class C covers smaller vehicles that carry 16 or more people or placarded hazardous materials.

    Source: 49 CFR 383.91(a)(1) (Class A definition)Report a problem with this question

57. 57. You hold a CDL with no endorsements. Which statement about hauling hazardous materials is true?

    • A.You may haul placarded loads as long as the trip stays inside one state
    • B.You may haul hazardous materials in quantities that do not require placards✓ Answer
    • C.You may haul any hazardous material as long as the shipping papers are correct
    • D.You may never transport any material classified as hazardous

    The H endorsement is triggered by placarding, not by the material itself: many shipments are small enough that no placards are required, and those may be hauled on a basic CDL. Driving a placarded vehicle without the endorsement is a crime, which is why every CDL applicant must be able to recognize hazardous cargo and know when placards apply.

    Source: AAMVA Model CDL Manual Sec. 2.23; 49 CFR 383.93(b)(4) (H endorsement)Report a problem with this question

Practice questions based on the AAMVA/FMCSA model CDL manual. Requirements vary by state — study your state's official CDL manual before your exam. Official CDL info →