Idaho ITD CDL General Knowledge Practice Test 10
- Questions50
- Correct to pass40
- Passing score80%
- Minimum age18 years
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1. You pick up a trailer that another driver dropped in the yard. What must you do before pulling it?
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Answer B: Inspect it yourself, because you are responsible for the whole vehicle you drive
Responsibility follows the driver who moves the vehicle, and a trailer that has stood in a yard may have lost air, developed a flat tire or been damaged.
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2. An article of cargo has been blocked so that it cannot move forward. How many tiedowns does the federal rule call for?
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Answer A: One tiedown for every 10 feet of article length, or any part of that
Blocking against forward movement lowers the requirement to one tiedown per 10 feet of length or fraction of 10 feet.
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3. What are the rules for using your turn signal before a turn or lane change?
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Answer A: Signal early, keep the signal on until the turn is finished, then cancel it
An early, continuous signal tells others what you plan to do; cancelling afterward keeps the signal from misleading them.
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4. You stop to check the load. Which set of things are you looking at?
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Answer C: Tight tiedowns, cargo that has not moved, secure doors and tarps still fastened
A cargo check covers the load and everything holding it: whether it has shifted, whether the devices are still tight, and whether doors and covers are still closed and fastened.
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5. When must a post-trip inspection be made?
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Answer D: At the end of each day the driver operates the vehicle
The post-trip inspection closes out each driving day so that anything found is recorded before the vehicle is handed to the next driver.
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6. Why must tiedowns be rechecked during a trip even when they were tight at the start?
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Answer C: Road vibration and cargo movement can loosen them as the miles go by
Straps and chains settle and loosen as the vehicle bounces and the cargo shifts slightly, so the load must be rechecked at the required intervals.
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7. You are hauling a sealed trailer and have been told in writing not to open it. How does that affect the en route cargo checks?
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Answer C: You do not have to inspect the cargo itself, but the vehicle and weight are still yours
The en route cargo inspection rule does not apply to a driver of a sealed vehicle who has been ordered not to open it, but every other responsibility, including legal weight, remains.
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8. You drop your phone on the floor of the cab while driving. What do federal rules require?
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Answer A: Leave it, because reaching for it while driving is banned
Federal rules forbid reaching for a mobile device in any way that takes the driver out of a seated, belted driving position.
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9. If an intersection has two lanes marked for left turns, which one should a large vehicle use?
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Answer D: The right hand of the two turning lanes
The outside turning lane leaves room for the rear of the vehicle to swing without striking a vehicle in the adjacent lane.
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10. You are given a ratchet strap with a deep cut along one edge. What should you do?
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Answer C: Do not use it; a damaged tiedown cannot be relied on to hold its rated load
Cuts, burns, knots and broken stitching weaken a strap far below its marked working load limit, so it must be taken out of service.
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11. You need to pull off onto the shoulder because of a problem with the load. How should you communicate that to other drivers?
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Answer D: Signal the move, then switch on the four-way flashers once stopped
Other drivers need a signal before you leave the lane and a clear warning once the vehicle is stopped near the traffic lanes.
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12. What are you checking on the mud flaps during the walkaround?
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Answer C: That they are securely attached, not torn and not dragging on the ground
A flap that is torn or hanging loose stops shielding following traffic from spray and stones, and a dragging flap can catch and tear away on the road.
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13. How do you avoid the sharp lurch that comes at the very end of a stop in a heavy vehicle?
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Answer A: Ease off the brake pressure just before the vehicle actually comes to rest
A smooth stop is finished by reducing pedal pressure as the vehicle settles, so the suspension does not rock the cab and the load forward.
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14. Which parts of total stopping distance can a driver shorten simply by staying alert and looking far ahead?
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Answer B: Perception distance and reaction distance
Alertness shortens the time spent recognizing a hazard and moving your foot to the pedal; braking distance depends on speed, weight, brakes and the road surface.
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15. Your windshield washer reservoir is empty and rain and road spray are expected. What should you do?
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Answer D: Fill it before the trip, because you need the washers to keep the windshield clear
Wipers alone smear the film of oil and grit thrown up by traffic, so the washers are part of keeping a usable view of the road.
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16. What tells a driver when to shift up in a vehicle with a manual transmission?
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Answer C: Engine speed in rpm together with road speed
Shift points are judged from engine rpm and road speed, using the operating range the manufacturer specifies for that engine.
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17. You are entering a freeway from a short ramp with a fully loaded trailer. What should you do?
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Answer A: Begin building speed early and wait for a large gap
A loaded vehicle accelerates slowly, so it needs both a running start and a much larger gap than a car would use.
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18. How much sleep does a typical adult driver need each day to stay properly alert?
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Answer D: Seven to eight hours
Most adults need seven to eight hours of sleep in every 24 hours, and a driver who regularly gets less builds up a debt that shows up behind the wheel.
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19. What information does an inspection decal on a commercial vehicle carry?
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Answer B: The date of the inspection, where the inspection report is kept, and information identifying the vehicle
The decal shows when the inspection was done, the name and address of the entity that holds the inspection report, and which vehicle it belongs to, so an officer can confirm the inspection at a glance.
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20. A fire starts in the cargo area of a van trailer. Why should you keep the doors closed until firefighters arrive?
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Answer D: Opening the doors lets in air that feeds the fire
A fire in a closed van is starved of oxygen; opening the doors gives it the air it needs to flare up.
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21. A driver behind you wants to pass and you can see that the road ahead is clear. What should you do?
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Answer B: Do not signal the other driver to pass; let that driver decide when it is safe
Directing other drivers can cause a crash if you misjudge the gap, so leave the decision to the driver who is passing.
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22. Why should a driver avoid shifting gears in the middle of a turn at an intersection?
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Answer D: Shifting during the turn takes a hand off the wheel and can cost you control
Pick the gear before you begin turning; shifting in the turn removes a hand from the wheel and can interrupt power just when you need steady control.
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23. You hear air escaping from a trailer tire during the pre-trip. What should you do?
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Answer C: Have it repaired or replaced before the vehicle is driven
An audible leak means the tire is failing now, and federal rules do not allow a vehicle to be operated on a flat or leaking tire.
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24. You need to check your route on a navigation device. What is the correct approach?
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Answer D: Set it before the trip or after you have parked
Route programming is planning work, and it belongs to the time before the wheels turn or after the vehicle is safely parked off the roadway.
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25. How much free play in the steering wheel is enough to make a vehicle hard to steer and should be reported?
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Answer B: More than 10 degrees, roughly 2 inches of movement at the rim of a 20 inch wheel
Excess play means steering input is lost before the wheels respond, and more than about 10 degrees is treated as a defect.
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26. Which road users are hardest to see at night?
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Answer C: Pedestrians and cyclists in dark clothing
People on foot or on a bicycle carry no lights of their own in many cases, so they appear only when the headlights reach them.
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27. Two tires in a dual set have noticeably different diameters. Why is that a problem?
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Answer C: The larger tire carries more than its share of the load and can be overloaded
The taller tire touches the road first and takes most of the weight, so it runs overloaded and hot while the smaller one does little work.
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28. When turning left, what should a driver of a long vehicle do before beginning the turn?
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Answer B: Reach the center of the intersection so the rear wheels clear the corner
The rear wheels follow a tighter path than the front, so the vehicle must reach the center of the intersection before the turn begins.
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29. What is the purpose of blocking placed against cargo on a trailer deck?
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Answer B: To fill the space around the cargo so it cannot slide
Blocking is shaped to fit snugly against the cargo and fastened to the deck, removing the room the load would need in order to move.
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30. You pick up a sealed trailer at a shipper. What should you check before leaving the dock?
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Answer B: That the seal number matches the paperwork and that the doors are properly closed
You cannot look at a sealed load, but you can confirm that the seal is intact, that its number matches the documents and that the doors are secure.
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31. What is a bulkhead in a cargo body used for?
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Answer D: To divide the space and stop cargo from moving into another part of the body
A bulkhead is a solid partition that separates one part of the load space from another and blocks the cargo from moving past it.
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32. Why do worn tires lose grip so quickly on a wet road?
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Answer D: Shallow tread cannot move water out from under the tire
The grooves in a tire exist to channel water away so the rubber can touch the road, and a worn tire has lost that capacity.
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33. Which combination of warning devices meets the requirement for a stopped commercial vehicle?
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Answer A: Three reflective triangles, or six fusees, or three liquid burning flares
A vehicle may carry three bidirectional reflective triangles, six fusees or three liquid burning flares as its warning devices.
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34. Why should high beams not be used in fog?
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Answer A: The light reflects back off the droplets and blinds you
Fog is made of water droplets that scatter light straight back at the driver, so a stronger beam makes the wall of glare worse rather than better.
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35. How is the fluid level in an automatic transmission usually checked?
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Answer A: With the engine running, following the procedure in the operator manual
Most automatic transmissions are designed to be checked with the engine running, and the operator manual gives the exact conditions for that vehicle.
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36. What happens to braking performance if oil or grease reaches a brake lining?
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Answer B: That brake loses much of its effect and the vehicle can pull to one side
A contaminated lining cannot grip the drum, so that wheel contributes little braking and the vehicle pulls toward the side that is still working.
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37. When should a driver add space beyond the basic following distance rule?
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Answer D: On slippery roads and whenever visibility is poor
The seconds rule is a minimum for good conditions, so rain, snow, darkness and heavy traffic all call for more space than that.
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38. What must a written driver vehicle inspection report cover at the end of the day?
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Answer C: Any defect or deficiency that would affect safety or could cause a mechanical breakdown
The report identifies the vehicle and lists defects that affect safe operation or could lead to a breakdown, so they are repaired before the next trip.
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39. Apart from the risk of stalling, why is rolling backwards when starting on an upgrade so serious in a heavy vehicle?
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Answer D: You can strike the vehicle behind you, which is often much closer than you think
You cannot see how close the vehicle behind has stopped, and even a short roll back is enough to hit it.
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40. An oncoming vehicle at night has bright headlights that are making it hard to see. What should you do?
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Answer B: Look toward the right edge of your lane and avoid looking directly at the lights
Looking at the right edge of the road keeps your eyes off the glare while you stay in your lane; glare can leave you nearly blind for several seconds.
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41. What is wrong with resting your foot on the clutch pedal between shifts?
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Answer B: It slowly wears the clutch out, because the pressure plate is never fully engaged
Any weight on the pedal partly disengages the clutch, so it slips and wears; the foot belongs off the pedal once the shift is finished.
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42. What is the most common cause of a front-wheel skid, where the vehicle keeps going straight even though you turn the wheel?
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Answer B: Driving too fast for the conditions
A front-wheel skid usually comes from too much speed for the traction available; the only cure is to let the vehicle slow down and stop turning or braking so hard.
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43. What does the suspension system weight rating tell the driver?
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Answer A: The maximum weight that the manufacturer says the suspension can carry
Like tires and axles, suspensions have a manufacturer capacity, and loading beyond it can damage springs and air bags.
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44. What does the working load limit stamped on a chain or strap describe?
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Answer B: The maximum load the device is rated to hold in normal use
The working load limit is the rated safe capacity for everyday use, deliberately set well below the force that would break the device.
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45. You are loading a flatbed that has no sides or bulkheads. How must the cargo be held?
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Answer D: By tiedowns, blocking or bracing, since there are no walls to keep it from shifting or falling off
Open decks depend entirely on securement devices; every article must be tied down or otherwise immobilized so it cannot move, spill or fall.
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46. How do you confirm that the coupling is locked before pulling out of the yard?
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Answer D: By locking the trailer brakes and pulling gently forward against them
The tug test loads the coupling in the direction that would pull it apart, so if the jaws are not closed on the kingpin you find out at walking pace.
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47. The temperature is around freezing and the road looks wet. What is a practical way to tell whether it is icy?
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Answer C: Check for ice building up on the mirrors, antenna or the front of the vehicle
Ice that forms on the mirror, antenna or windshield is a warning that the road surface is freezing too, and black ice can look like a wet road.
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48. You have just passed another vehicle on a two lane road. What tells you it is safe to return to your lane?
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Answer B: You can see the whole front of that vehicle in your right mirror
Seeing the entire front of the vehicle you passed in your mirror proves you are far enough ahead to move back over without cutting the driver off.
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49. Why should the mirrors be checked repeatedly while you make a tight turn?
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Answer C: To watch the rear of the vehicle clear other vehicles and objects
In a long vehicle the rear wheels cut inside the path of the front wheels, so only the mirrors show whether the rear is clearing curbs, poles and other vehicles.
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50. When should a lower gear be selected for a long downgrade?
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Answer D: Before you start down the hill
The gear is chosen at the top, while speed is still low, because a heavy vehicle already rolling fast may not go into a lower gear at all.