Practice questions written from the official CDL manual. Correct answers and explanations are shown below each question. (Turn on JavaScript for the interactive practice and timed practice modes.)
1. What is the main reason a commercial driver performs a pre-trip inspection?
- ATo find problems that could cause a crash or breakdown before drivingCorrect
- BTo satisfy the shipper who loaded the freight
- CTo warm up the engine before a long trip
- DTo record the fuel level for the trip log
Why: A pre-trip inspection lets you catch mechanical problems before they cause a crash or leave you stranded. Finding a worn tire or a brake leak in the yard is far safer and cheaper than discovering it at highway speed.
Based on: CDL Manual §2.1 — Vehicle Inspection
2. During a pre-trip inspection, what is the minimum tread depth allowed on the front (steering axle) tires?
- A2/32 of an inch
- B1/32 of an inch
- C6/32 of an inch
- D4/32 of an inchCorrect
Why: Steering (front) tires must have at least 4/32 inch of tread in every major groove because a front-tire failure makes the truck very hard to steer. All other tires need at least 2/32 inch.
Based on: CDL Manual §11 — Vehicle Inspection (Tires)
3. What is the minimum tread depth required on tires other than the front steering tires?
- A4/32 of an inch
- B2/32 of an inchCorrect
- C3/32 of an inch
- DNo minimum, as long as tread is visible
Why: Drive and trailer tires must have at least 2/32 inch of tread in every major groove. The front steering tires have a higher requirement of 4/32 inch.
Based on: CDL Manual §11 — Vehicle Inspection (Tires)
4. Rust trails running out from wheel lug nuts most likely mean:
- AThe wheel is a different size than the others
- BThe tire is over-inflated
- CThe nuts may be looseCorrect
- DThe wheel bearing needs grease
Why: Rust trails around lug nuts are a warning sign that the nuts are loose. Loose or missing lug nuts can let a wheel come off, so check them carefully during inspection.
Based on: CDL Manual §11 — Vehicle Inspection (Wheels and Rims)
5. How should you check tire air pressure during an inspection?
- AUse a properly working tire pressure gaugeCorrect
- BKick or thump the tire to hear the sound
- CLook at the tire to see if it bulges
- DPress the tire with your hand
Why: You cannot judge air pressure accurately by look, feel, or sound. Use a tire pressure gauge to get a true reading, since low pressure causes heat buildup and tire failure.
Based on: CDL Manual §11 — Vehicle Inspection (Tires)
6. While driving, which of these is a good way to keep watch for problems that appear during the trip?
- ARely only on the pre-trip inspection you already did
- BWait for a warning light before checking anything
- CStop every 15 minutes for a full inspection
- DWatch the gauges and use your eyes, ears, and nose to notice troubleCorrect
Why: En-route, watch your instruments for signs of trouble and stay alert with your senses. You can often see, hear, smell, or feel a developing problem before it becomes a breakdown.
Based on: CDL Manual §2.1 — Vehicle Inspection (Inspection During a Trip)
7. How often should you check your tires during a long trip?
- AOnly at the start and the end of the trip
- BAt each stop, and whenever you have safety concernsCorrect
- COnly if a warning light comes on
- DEvery 500 miles, no matter what
Why: Check tires at each stop. A tire that is too hot to touch may be about to fail, so if you find a very hot tire you should stop until it cools before driving on it.
Based on: CDL Manual §2.1 — Vehicle Inspection (Inspection During a Trip)
8. What is the purpose of a post-trip inspection and report?
- ATo record how many miles you drove that day
- BTo prove to the shipper the load arrived safely
- CTo note any defects so they can be repaired before the vehicle is used againCorrect
- DTo reset the vehicle's warning lights
Why: A post-trip inspection and driver vehicle inspection report help make sure problems get fixed before the next driver uses the vehicle. Reporting defects keeps unsafe trucks off the road.
Based on: CDL Manual §2.1 — Vehicle Inspection (After-trip Inspection and Report)
9. A puddle of fluid under your vehicle or dripping from underneath is a sign of:
- AA possible leak that should be found and fixedCorrect
- BNormal condensation you can ignore
- COverfilled washer fluid
- DA tire losing air
Why: Leaks show up as puddles under the vehicle or as drips. Find the source and fix it before driving, because losing oil, coolant, fuel, or brake fluid can cause a serious failure.
Based on: CDL Manual §11 — Vehicle Inspection (Leaks)
10. On a vehicle with manual (non-power) steering, how much steering wheel play is too much?
- AAny play at all is unsafe
- BMore than 45 degrees
- CPlay is normal and never a concern
- DMore than 10 degrees (about 2 inches on a 20-inch wheel)Correct
Why: If the steering wheel can turn more than about 10 degrees (roughly 2 inches on a 20-inch wheel) before the front wheels move, it can be hard to steer. That much free play should be repaired.
Based on: CDL Manual §11 — Vehicle Inspection (Steering System)
11. The correct way to hold the steering wheel is:
- AWith one hand at the top
- BFirmly with both hands on opposite sides of the wheelCorrect
- CLoosely with your fingertips
- DWith both hands close together at the bottom
Why: Hold the wheel firmly with both hands, placed on opposite sides. A good grip keeps you in control if you hit a bump or a tire blows out and the wheel jerks in your hands.
Based on: CDL Manual §2.2 — Basic Control of Your Vehicle (Steering)
12. When you must back a truck, the best practice is to:
- ABack quickly to get it over with
- BBack toward the passenger (blind) side whenever you can
- CBack toward the driver's side and use a helper when possibleCorrect
- DRely only on your mirrors and never get out
Why: Back toward the driver's side so you can see better, back slowly, and use a helper when one is available. Get out and look at your path before and during backing to avoid what you cannot see.
Based on: CDL Manual §2.2 — Basic Control of Your Vehicle (Backing Safely)
13. Why should you back toward the driver's side rather than the passenger side when you have a choice?
- AYou can see the rear of the vehicle better on the driver's sideCorrect
- BIt is required by federal law
- CIt puts less wear on the tires
- DThe mirrors only work on that side
Why: Backing toward the driver's side lets you watch the rear of your vehicle by looking out the side window, giving a much clearer view than the blind passenger side.
Based on: CDL Manual §2.2 — Basic Control of Your Vehicle (Backing Safely)
14. The main reason to double-clutch and time your shifts with engine speed (rpm) is to:
- ASave fuel on flat roads
- BMake the engine run cooler
- CReduce brake wear
- DShift smoothly without grinding or damaging the gearsCorrect
Why: Correct rpm and double-clutching let the gears mesh smoothly. Shifting at the wrong speed grinds the gears, can damage the transmission, and may leave you unable to get back into gear.
Based on: CDL Manual §2.3 — Shifting Gears
15. Before starting down a long, steep downgrade, you should:
- AShift into neutral to save fuel
- BShift to a lower gear before you start downCorrect
- CWait until you pick up speed, then downshift
- DKeep the same gear you used on the flat
Why: Select a low gear before you start down a grade. On many trucks it is hard or impossible to downshift once you are moving fast, so choosing the right gear early keeps the engine helping to slow you.
Based on: CDL Manual §2.3 — Shifting Gears (Special Conditions)
16. How far ahead should you normally look while driving?
- AAbout 2 to 4 seconds ahead
- BJust to the vehicle directly in front of you
- CAbout 12 to 15 seconds aheadCorrect
- DAs far as your headlights reach, day or night
Why: Good drivers look 12 to 15 seconds ahead, about one block in the city or a quarter mile on the highway. Looking far ahead lets you spot hazards early and react smoothly instead of at the last second.
Based on: CDL Manual §2.4 — Seeing (Looking Ahead)
17. Objects seen in a convex (curved) side mirror appear:
- ASmaller and farther away than they really areCorrect
- BLarger and closer than they really are
- CExactly their true size and distance
- DUpside down
Why: Convex mirrors show a wider area, but they make everything look smaller and farther away than it really is. Remember this so you do not misjudge how close a vehicle actually is.
Based on: CDL Manual §2.4 — Seeing (Using Mirrors)
18. When should you check your mirrors?
- AOnly before reversing
- BRegularly, and before and during turns, merges, lane changes, and tight maneuversCorrect
- COnly when another vehicle sounds its horn
- DOnly at intersections
Why: Check mirrors regularly to monitor traffic and your vehicle. Check before and during maneuvers, while keeping each glance brief enough to maintain attention to the road ahead.
Based on: CDL Manual §2.4 — Seeing (Using Mirrors)
19. To communicate that you intend to turn, you should signal:
- AOnly after you begin turning
- BEarly and keep signaling until you finish the turnCorrect
- CJust as you start braking for the turn
- DBy tapping your horn instead
Why: Signal early so others have time to react, and keep signaling through the turn because your hands are busy steering. Turn the signal off afterward if it does not cancel by itself.
Based on: CDL Manual §2.5 — Communicating (Signal Your Intentions)
20. When you slow down suddenly or must stop where drivers behind may not expect it, a good way to warn them is to:
- ATurn on your high beams
- BWave your arm out the window
- CTap the brake pedal a few times to flash the brake lightsCorrect
- DTurn the steering wheel back and forth
Why: Tapping the brakes flashes your brake lights and warns following drivers early. This is helpful when you must slow well below the flow of traffic or stop where others might not expect it.
Based on: CDL Manual §2.5 — Communicating (Communicate You Are Slowing Down)
21. After stopping on the side of the road, how soon must you place your emergency warning devices (reflective triangles)?
- AWithin 10 minutesCorrect
- BWithin 30 minutes
- COnly if you will be stopped over an hour
- DThere is no time requirement
Why: Turn on your emergency flashers right away and put out your warning devices within 10 minutes. Triangles warn other drivers that a large, stopped vehicle is ahead so they can move over in time.
Based on: CDL Manual §2.5 — Communicating (Warning Devices)
22. On a two-way, undivided road, where should you normally place three warning triangles after stopping?
- AWithin 10 feet near the traffic side, plus 100 feet ahead and 100 feet behindCorrect
- BAll three immediately behind the vehicle
- C10, 100, and 200 feet behind the vehicle
- DAll three on the opposite shoulder
Why: Mark the vehicle near its traffic-side front or rear corner, then warn traffic approaching from both directions with a triangle about 100 feet ahead and behind. Hills, curves, and other sight obstructions require adjustment so approaching drivers receive adequate warning.
Based on: CDL Manual §2.5 — Communicating (Warning Devices)
23. The total stopping distance of a vehicle is made up of:
- ABraking distance only
- BPerception distance, reaction distance, and braking distanceCorrect
- CReaction distance and vehicle weight
- DFollowing distance and braking distance
Why: Total stopping distance adds three parts: perception distance (while you notice the hazard), reaction distance (while you move your foot to the brake), and braking distance (while the brakes stop the truck).
Based on: CDL Manual §2.6 — Controlling Speed (Stopping Distance)
24. At about 55 mph on dry pavement with good brakes, your total stopping distance is closest to:
- AAbout 100 feet
- BAbout 200 feet
- CAbout 420 feetCorrect
- DAbout 300 feet
Why: At 55 mph the total stopping distance is roughly 419 feet, which is longer than a football field. This total includes the time to perceive the hazard, react, and then brake to a stop.
Based on: CDL Manual §2.6 — Controlling Speed (Stopping Distance)
25. Which part of stopping distance is the time it takes to move your foot from the accelerator to the brake once you decide to stop?
- AReaction distanceCorrect
- BPerception distance
- CBraking distance
- DFollowing distance
Why: Reaction distance is how far the vehicle travels from the moment your brain tells your foot to brake until your foot actually presses the pedal, usually about 3/4 to 1 second for an alert driver.
Based on: CDL Manual §2.6 — Controlling Speed (Stopping Distance)
26. If you double your speed, your braking distance will:
- AStay about the same
- BDouble
- CDecrease slightly
- DIncrease about four timesCorrect
Why: Braking distance grows with the square of speed. Doubling your speed roughly quadruples the distance needed to stop, which is why small increases in speed greatly increase crash risk.
Based on: CDL Manual §2.6 — Controlling Speed (Effect of Speed on Stopping Distance)
27. Compared with a loaded truck, an empty truck usually:
- AStops in a much shorter distance
- BNeeds a greater stopping distance because it has less tractionCorrect
- CHandles exactly the same
- DCannot skid at all
Why: Empty trucks often need a longer stopping distance because there is less weight pressing the tires down, giving less traction. Empty trailers can bounce and lock up wheels, hurting braking.
Based on: CDL Manual §2.6 — Controlling Speed (Effect of Vehicle Weight on Stopping Distance)
28. On wet roads, your stopping distance compared with dry roads is about:
- AHalf as long
- BThe same
- CTwice as longCorrect
- DTen times as long
Why: Wet pavement can double your stopping distance because water reduces traction. You should reduce speed by about one third on wet roads to keep a safe margin.
Based on: CDL Manual §2.6 — Controlling Speed (Matching Speed to the Road Surface)
29. Hydroplaning can begin at speeds as low as:
- A30 mphCorrect
- B10 mph
- C50 mph
- D70 mph
Why: With enough water on the road, tires can ride up on the water and lose contact with the pavement at speeds as low as 30 mph. Low tire pressure or worn tread makes hydroplaning more likely.
Based on: CDL Manual §2.6 — Controlling Speed (Hydroplaning)
30. If your vehicle starts to hydroplane, you should:
- ABrake hard immediately
- BSpeed up to push through the water
- CTurn the wheel sharply
- DRelease the accelerator and push in the clutch to let the wheels turn freelyCorrect
Why: When hydroplaning, do not brake or turn hard. Ease off the accelerator and push in the clutch to slow gently and let the wheels keep turning until the tires regain grip on the road.
Based on: CDL Manual §2.6 — Controlling Speed (Hydroplaning)
31. You should slow for a curve:
- AWhile turning through the curve
- BBefore you enter the curveCorrect
- COnly if the curve is marked with a sign
- DAfter you exit the curve
Why: Slow down before entering a curve, then hold a steady speed or accelerate gently through it. Braking hard in a curve can cause the vehicle to skid because the tires are already working hard to turn.
Based on: CDL Manual §2.6 — Controlling Speed (Speed and Curves)
32. The rule of thumb for following distance below 40 mph is:
- ATwo seconds no matter how long the vehicle is
- BOne car length for every 10 mph
- COne second for each 10 feet of vehicle lengthCorrect
- DThree seconds for any commercial vehicle
Why: Below 40 mph, allow at least one second of following distance for every 10 feet of vehicle length. A 60-foot rig would need at least 6 seconds of space to the vehicle ahead.
Based on: CDL Manual §2.7 — Managing Space (Space Ahead)
33. When you are driving faster than 40 mph, how should you adjust your following distance?
- AAdd one second to the one-second-per-10-feet countCorrect
- BSubtract one second
- CKeep the same number of seconds
- DCut the distance in half
Why: At speeds over 40 mph, add one second to the following distance. So a 60-foot rig needing 6 seconds under 40 mph should allow 7 seconds when going faster.
Based on: CDL Manual §2.7 — Managing Space (Space Ahead)
34. To measure your following distance, you should:
- AEstimate the number of car lengths ahead
- BWatch your speedometer only
- CCheck the distance in your side mirror
- DCount the seconds it takes to reach a fixed point after the vehicle ahead passes itCorrect
Why: Pick a landmark the vehicle ahead passes, then count the seconds until your front bumper reaches the same spot. Compare that count to the one-second-per-10-feet rule to see if you have enough space.
Based on: CDL Manual §2.7 — Managing Space (Space Ahead)
35. Why is the space above your vehicle a concern for truck drivers?
- AIt affects fuel mileage
- BLow bridges, wires, and signs may not give enough clearance for a tall vehicleCorrect
- CIt changes how the brakes work
- DIt only matters in the rain
Why: Overhead clearance matters because low bridges, wires, and overhangs can strike a tall trailer. Do not assume posted heights are exact, since a heavy load can lower the vehicle and pavement repaving can reduce clearance.
Based on: CDL Manual §2.7 — Managing Space (Space Overhead)
36. Because a large vehicle needs a big gap to cross or enter traffic, you should remember that:
- AYou can accelerate as fast as a car
- BOther drivers will always slow for you
- CIt takes far longer to get up to speed, so you need a much larger gapCorrect
- DGaps that work for cars work fine for trucks
Why: A loaded truck accelerates slowly and needs a much larger gap than a car to pull into or cross traffic. Judge the gap by the time it takes you to get fully across, not by how a car would do it.
Based on: CDL Manual §2.7 — Managing Space (Space to Cross or Enter Traffic)
37. At night, you should dim your high beams when an oncoming vehicle is within about:
- A500 feetCorrect
- B100 feet
- C1,000 feet
- DYou never need to dim them
Why: Dim your high beams within 500 feet of an oncoming vehicle, and also when following within 500 feet. High beams in another driver's eyes can blind them and cause a crash.
Based on: CDL Manual §2.11 — Driving at Night (Use High Beams When You Can)
38. At night you should drive slowly enough that you can:
- AKeep up with all other traffic
- BReach your destination on time
- CRead every road sign at full speed
- DStop within the distance you can see ahead with your headlightsCorrect
Why: Because you can see only as far as your headlights reach, keep your speed low enough to stop within that lighted distance. Outdriving your headlights means you could hit something before you can react.
Based on: CDL Manual §2.11 — Driving at Night (Adjust Speed to Keep Stopping Distance Within Sight Distance)
39. Long, boring stretches of highway at night can cause "highway hypnosis." The best defense is to:
- ATurn up the radio very loud
- BKeep your eyes moving and take breaks to stay alertCorrect
- CSpeed up to finish sooner
- DTurn off your headlights briefly to wake up
Why: Highway hypnosis is a drowsy, trance-like state from staring straight ahead. Keep your eyes moving, scan the road and mirrors, and stop for a break or rest when you feel drowsy.
Based on: CDL Manual §2.11 — Driving at Night (Fatigue and Lack of Alertness)
40. The safest thing to do in dense fog is usually to:
- AUse your high beams for more light
- BSpeed up to get out of the fog quickly
- CPostpone driving or pull off the road until it clearsCorrect
- DFollow closely behind another vehicle's taillights
Why: It is best not to drive in dense fog. If you are caught in it, slow down, use low beams and fog lights, and consider pulling completely off the road until it lifts. High beams reflect off fog and make seeing worse.
Based on: CDL Manual §2.12 — Driving in Fog
41. In cold weather, which part of the road is most likely to freeze first?
- ABridges and overpassesCorrect
- BThe middle of long straight stretches
- CRoads next to buildings
- DUphill sections
Why: Bridges and overpasses freeze before other roads because cold air passes above and below them. Slow down before you reach a bridge in freezing weather, even if the road looks clear.
Based on: CDL Manual §2.13 — Winter Driving (Watch for Icy Roads)
42. A shiny, wet-looking surface on a road when temperatures are near or below freezing may be:
- AFresh paint
- BSpilled fuel
- CLoose gravel
- DBlack ice you can barely seeCorrect
Why: Black ice is a thin, clear layer of ice that makes the road look wet. Near freezing, a wet look may actually be ice, so watch for it on bridges and shaded spots and reduce your speed.
Based on: CDL Manual §2.13 — Winter Driving (Black Ice)
43. When driving a long, steep downgrade in the mountains, your main braking should come from:
- AHolding the service brakes down the whole way
- BA low gear and the engine's braking effect, using the brakes to supplementCorrect
- CCoasting in neutral
- DPumping the brakes constantly
Why: On mountain downgrades, choose a low gear so the engine helps hold your speed, and use the brakes only to supplement. Riding the brakes the whole way overheats them and can cause brake fade.
Based on: CDL Manual §2.16 — Mountain Driving (Select a Safe Speed)
44. Brake fade on a long downgrade is mainly caused by:
- ABrakes that are too cold
- BWet brake linings
- COverheating the brakes from using them too muchCorrect
- DLow tire pressure
Why: Using the brakes too much on a long grade overheats them, and hot brakes lose their stopping power, called brake fade. Proper gear selection keeps the brakes cooler and working when you need them.
Based on: CDL Manual §2.16 — Mountain Driving (Brake Fading or Failure)
45. An escape ramp on a downgrade is designed to:
- AStop a runaway vehicle whose brakes have failedCorrect
- BGive slow trucks a place to pass
- CProvide a rest area
- DLet vehicles turn around
Why: Escape ramps use soft gravel or an upgrade to safely stop a vehicle that has lost its brakes. If your brakes fail on a downgrade, use the escape ramp rather than trying to ride it out.
Based on: CDL Manual §2.16 — Mountain Driving (Escape Ramps)
46. Which of these is an important clue that a hazard may be developing?
- AA car traveling at a steady, normal speed
- BAn empty parking lot
- CA green traffic light far ahead
- DA driver ahead who is distracted or looks confusedCorrect
Why: Confused, distracted, or hesitating drivers are hazards because they may do something unexpected. Spotting these clues early gives you time to slow down or make space before a problem happens.
Based on: CDL Manual §2.8 — Seeing Hazards (Drivers Who Are Hazards)
47. Recognizing a hazard early is important mainly because it:
- ALets you honk sooner
- BGives you time to plan and reduce the chance of an emergencyCorrect
- CImproves your fuel mileage
- DIs required to pass the road test only
Why: Seeing a hazard early gives you time to react calmly, adjust speed, and make space before it becomes an emergency. Drivers who spot hazards late are forced into sudden, risky moves.
Based on: CDL Manual §2.8 — Seeing Hazards (Importance of Seeing Hazards)
48. Texting while driving a commercial vehicle is dangerous mainly because:
- AIt drains the phone battery
- BIt uses too much data
- CIt takes your eyes off the road for several seconds at a timeCorrect
- DIt is only a problem at night
Why: Texting takes your eyes off the road long enough to travel the length of a football field at highway speed. Federal rules prohibit texting and hand-held phone use while driving a commercial vehicle.
Based on: CDL Manual §2.9 — Distracted Driving
49. If another driver is behaving aggressively toward you (tailgating, honking, cutting in), you should:
- AStay calm, avoid eye contact, and give them room to passCorrect
- BSpeed up to get away and teach them a lesson
- CMake eye contact so they know you see them
- DBrake suddenly to warn them
Why: Do not challenge an aggressive driver. Stay calm, avoid eye contact, and give them plenty of room to go around. Trying to "get even" only raises the risk of a serious crash or road rage.
Based on: CDL Manual §2.10 — Aggressive Drivers and Road Rage
50. A CDL holder operating a commercial vehicle is considered legally impaired at a blood alcohol concentration (BAC) of:
- A0.08 or higher
- B0.10 or higher
- CAny measurable amount
- D0.04 or higherCorrect
Why: Driving a commercial vehicle with a BAC of 0.04 or higher is against the law and will disqualify your CDL. This limit is stricter than the 0.08 limit for regular drivers.
Based on: CDL Manual §2.22 — Alcohol, Other Drugs, and Driving
51. What actually helps a person who has been drinking become sober?
- ADrinking black coffee
- BOnly the passage of timeCorrect
- CTaking a cold shower
- DEating a large meal
Why: Nothing but time lets the body remove alcohol. Coffee, cold showers, and food do not speed it up. If you have been drinking, only waiting will lower your blood alcohol level.
Based on: CDL Manual §2.22 — Alcohol, Other Drugs, and Driving (How Alcohol Works)
52. The first thing alcohol usually affects in a driver is:
- AVision only
- BHearing
- CJudgment and self-controlCorrect
- DGrip strength
Why: Alcohol affects judgment and self-control first, often before a driver feels drunk. That is dangerous because impaired drivers may take risks and believe they are driving fine when they are not.
Based on: CDL Manual §2.22 — Alcohol, Other Drugs, and Driving (Effects of Alcohol)
53. What should a driver do before driving while taking a prescription medicine?
- AAssume every prescription is safe for commercial driving
- BTake half the dose without asking the prescriber
- CCheck applicable drug rules and consult a treating practitioner familiar with the driver’s history and dutiesCorrect
- DDrive if the package has no driving warning
Why: A prescription alone does not establish qualification. Some drugs are prohibited; permitted prescription use must meet the applicable rules and the practitioner must advise that it will not adversely affect safe driving. The medical examiner also assesses qualification.
Based on: 49 CFR 391.41
54. To help stay alert and avoid fatigue on a long trip, you should:
- ADrive faster to shorten the trip
- BRely on pep pills or energy drinks
- CKeep the cab very warm
- DGet enough sleep before the trip and take breaks along the wayCorrect
Why: The best defenses against fatigue are getting enough sleep before driving and taking regular breaks. Stimulant pills do not make up for lost sleep and can make you feel worse when they wear off.
Based on: CDL Manual §2.23 — Staying Alert and Fit to Drive
55. If you become sleepy while driving, the safest thing to do is:
- AOpen the window and turn up the radio
- BStop driving and get some rest or sleepCorrect
- CDrink coffee and keep going
- DSlow down and continue
Why: The only real cure for sleepiness is sleep. Cold air, loud music, and coffee are temporary at best. When drowsy, leave the road at a safe place and rest before continuing.
Based on: CDL Manual §2.23 — Staying Alert and Fit to Drive (Sleep)
56. Even without a hazmat endorsement, every commercial driver should be able to:
- ARepackage leaking hazardous materials
- BTest chemicals for their hazard class
- CRecognize placards that mark hazardous materialsCorrect
- DSet their own placement rules for placards
Why: All commercial drivers must be able to recognize hazardous materials placards, the diamond-shaped signs on vehicles. This helps you know when a load requires a hazmat endorsement and special handling.
Based on: CDL Manual §2.23 — Hazardous Materials Rules For All Commercial Drivers
57. Hazardous materials placards on a vehicle are:
- ADiamond-shaped warning signsCorrect
- BRound green signs
- CRectangular blue signs
- DTriangular yellow signs
Why: Placards are diamond-shaped signs that warn others of a hazardous load. Learning to recognize them keeps you from unknowingly hauling hazardous materials without the required endorsement and precautions.
Based on: CDL Manual §2.23 — Hazardous Materials Rules For All Commercial Drivers
58. The most common cause of serious skids is:
- AUnderinflated tires
- BSteering too slowly
- CUsing the parking brake
- DDriving too fast for conditionsCorrect
Why: Most serious skids come from driving too fast for the road and weather. Over-braking, over-steering, and over-accelerating also cause skids, and all trace back to going faster than conditions allow.
Based on: CDL Manual §2.19 — Skid Control and Recovery (Causes of Skids)
59. If your drive wheels begin to skid because of hard acceleration, you should first:
- APress the accelerator harder
- BStop accelerating (and push in the clutch) to let the wheels regain gripCorrect
- CJam on the brakes
- DTurn the wheel sharply the same direction as the skid
Why: A drive-wheel skid from too much power is fixed by taking your foot off the accelerator (and pushing in the clutch) so the wheels can slow and grip again, then steering to stay on course.
Based on: CDL Manual §2.19 — Skid Control and Recovery (Drive-wheel Skids)
60. At the scene of a crash, after protecting the area and notifying authorities, you should care for the injured by:
- AMoving every injured person to the roadside right away
- BGiving injured people food and water
- CNot moving a seriously injured person unless there is danger such as fireCorrect
- DLeaving the scene to find help
Why: First protect the area with flashers and warning devices and call for help. Then care for the injured, but do not move a seriously hurt person unless leaving them risks greater harm, such as fire.
Based on: CDL Manual §2.20 — Accident Procedures