Idaho ITD CDL General Knowledge Practice Test 5
Test 5 of 5. Pick an answer for each question to see if it is right and why; your score appears at the end. You need 40 correct answers to pass, the same ratio as the real Idaho test.
- Questions50
- Correct to pass40
- Passing score80%
- Minimum age18 years
-
1. Why should both outside mirrors be checked over and over while backing?
Show answer
Answer B: Each mirror covers only part of the path and neither covers the blind spots, so people and objects can appear without warning
Working both mirrors in turn is the only way to follow the whole path of a vehicle you cannot see behind.
-
2. What is the correct order for a basic double clutch upshift?
Show answer
Answer B: Release the accelerator and push the clutch, shift to neutral, release the clutch, let engine speed drop, push the clutch again and shift to the higher gear
Double clutching passes through neutral with the clutch released so engine speed can drop to match the next gear before it is engaged.
-
3. A dispatcher tells you to take a trailer you believe is loaded badly enough to be unsafe. What should you do?
Show answer
Answer C: Refuse to move it until the load has been made safe
The driver may not operate a vehicle whose cargo is not properly distributed and secured, and an instruction from an employer does not change that.
-
4. You must drive well below the speed of surrounding traffic, for example when climbing a steep grade with a heavy load. What should you do?
Show answer
Answer B: Turn on the four-way flashers to warn following traffic, where state law allows it
Flashers warn faster traffic that a slow-moving vehicle is ahead, which helps prevent rear-end crashes; some states restrict their use while moving, so check the local rule.
-
5. How long do Idaho CDL knowledge test results stay valid, and how soon may a failed test be retaken?
Show answer
Answer D: Valid for one year, with a three-day wait before retesting
Idaho CDL written test results remain valid for one year from the date passed, and an applicant who fails must wait three days and pay the fee again before retesting.
-
6. What should be checked about the power steering system in the engine compartment?
Show answer
Answer D: That the fluid level is correct and the hoses and pump are not leaking
Losing power steering fluid means losing steering assistance, which can happen suddenly and makes a heavy vehicle very hard to turn.
-
7. You press on a drive belt and it deflects far more than the others. What does that suggest?
Show answer
Answer C: The belt is too loose and the part it drives may not work properly
A belt with excessive play slips on its pulleys, so the accessory it drives turns too slowly or not at all under load.
-
8. An unblocked crate 4 feet long and weighing 1,500 pounds needs at least how many tiedowns?
Show answer
Answer A: Two
A short article that weighs more than 1,100 pounds requires at least two tiedowns even though it is under 5 feet long.
-
9. In very hot weather, how often should you check the tires during a trip?
Show answer
Answer D: About every two hours or every 100 miles
Heat raises tire pressure and can lead to blowouts, so tires are checked about every two hours or 100 miles when it is very hot.
-
10. A car ahead of you keeps drifting within its lane and moving unevenly. What should you assume?
Show answer
Answer C: The driver may be distracted, lost or impaired
Unsteady lane keeping is a classic clue to a driver who is not in full control, so the safe response is to keep back and give plenty of room.
-
11. How does a front tire failure usually feel to the driver?
Show answer
Answer D: The steering suddenly becomes heavy and pulls to one side
A failed front tire loads the steering and makes the wheel feel heavy, while a rear tire failure shows up as the back end swaying.
-
12. When should mirror adjustment be checked, and what should each mirror show?
Show answer
Answer B: Before every trip, with each mirror adjusted to show some part of the vehicle
Checking the mirrors before each trip and keeping a small part of the vehicle in view gives a reference point for judging distance behind and beside you.
-
13. Besides the hours when the law requires them, when should headlights be switched on?
Show answer
Answer A: Any time visibility is poor, such as in rain, fog or at dusk
Headlights are used to be seen as much as to see, so they belong on whenever light or weather makes the vehicle harder to spot.
-
14. When should a driver select the gear for a long, steep downgrade?
Show answer
Answer B: Before starting down the grade
The low gear has to be chosen before the descent, because a heavy vehicle gaining speed may refuse to shift down at all.
-
15. Which vehicles are most likely to get hung up on a raised railroad crossing?
Show answer
Answer A: Low-slung units such as car carriers and lowboys
Vehicles with low ground clearance or a long wheelbase can bottom out on a humped crossing and become stuck on the tracks.
-
16. You have backed into the same loading bay every week for a year. How often should you still get out and walk to the rear before backing?
Show answer
Answer D: Every time, since the area can change while you are away from it
A familiar space is no guarantee; vehicles, pallets, people and overhead obstructions appear between one visit and the next, so you check on every occasion.
-
17. Which of these is NOT on the federal list of parts and accessories the driver must be satisfied are in good working order before driving?
Show answer
Answer D: The seat cushion upholstery
The federal pre-trip rule names brakes, steering, lights and reflectors, tires, horn, wipers, mirrors, coupling devices, wheels and rims, and emergency equipment; seat upholstery is not on that list.
-
18. The combined working load limit of the tiedowns on a load must equal at least what share of the cargo weight?
Show answer
Answer C: One half of the cargo weight
Federal securement rules set the aggregate working load limit at no less than half the weight of the article or group of articles being held.
-
19. You are drifting in the lane, yawning constantly and cannot remember the last few miles. What is the only reliable cure?
Show answer
Answer C: Stopping in a safe place and sleeping
Those are classic drowsiness warning signs, and nothing except sleep repays the sleep the body is missing.
-
20. What is the danger of letting engine speed climb past the top of the rated rpm range before you shift?
Show answer
Answer B: You can damage the engine, so the shift should be made before that point
Every engine has a rated operating range; running above it can cause serious engine damage, so the upshift belongs at the top of that range, not beyond it.
-
21. What are you checking when you look at the batteries during the engine compartment inspection?
Show answer
Answer D: That they are securely mounted, the connections are tight and free of corrosion, and the caps are in place
Loose or corroded batteries can fail or short out, so the mount, cables, terminals and vent caps are all part of the check.
-
22. When is a road surface usually most slippery during a rain shower?
Show answer
Answer A: Just after the rain starts, when water mixes with oil and dirt on the surface
The first rain lifts oil and dust into a slick film that has not yet been washed away, so the road is more slippery than it will be later.
-
23. What is the correct order for a double clutch downshift?
Show answer
Answer D: Release the accelerator and push the clutch to reach neutral, release the clutch and press the accelerator to raise engine speed, then push the clutch again and select the lower gear
A lower gear turns faster than the one being left, so engine speed has to be raised in neutral before that gear will engage cleanly.
-
24. With water standing on the road, hydroplaning can begin at speeds as low as what?
Show answer
Answer D: 30 mph
When enough water covers the surface, the tires can ride up on it and lose contact at speeds as low as 30 mph.
-
25. How should speed and gears be handled when approaching a curve?
Show answer
Answer A: Slow to a safe speed and downshift before entering the curve
Braking and shifting are completed before the curve so the vehicle is settled and can pull gently through it without upsetting the load.
-
26. How does overloading affect the way a vehicle drives?
Show answer
Answer C: It slows the vehicle on upgrades, makes stopping take longer and can overheat the brakes on downgrades
Extra weight demands more from the engine and the brakes, so the vehicle climbs slowly and needs much more distance to stop.
-
27. Under the federal hours of service rules, when must a property-carrying driver take a 30 minute break?
Show answer
Answer C: After 8 cumulative hours of driving time
Driving is not allowed after 8 cumulative hours of driving time without at least a 30 consecutive minute interruption of driving.
-
28. You are told a posted bridge ahead has a weight limit lower than your gross weight. What must you do?
Show answer
Answer C: Take a route that avoids it, because a posted limit is a legal limit
A posted structure limit must be obeyed exactly as any other weight limit, so a heavier vehicle has to be routed around it.
-
29. You need fuel and the canopy over the pumps is low. What is the safe way to handle the clearance?
Show answer
Answer B: Stop and check the height at the entrance and at the way out before committing
Clearance can differ at the entry, under the canopy and at the exit, and a sloping approach changes the effective height, so both ends have to be checked.
-
30. On a one way street or a divided highway, where are the warning devices placed?
Show answer
Answer B: About 10 feet, 100 feet and 200 feet back toward the approaching traffic
When traffic can only come from one side, all three devices are spread out behind the vehicle to give approaching drivers a longer warning.
-
31. Before raising the hood to inspect the engine compartment, what should you do?
Show answer
Answer B: Shut off the engine, set the parking brake and chock the wheels if needed
The engine compartment is inspected with the engine off and the vehicle secured so nothing can move or turn while your hands are inside.
-
32. How does a driver measure following distance in seconds?
Show answer
Answer A: Wait for the vehicle ahead to pass a fixed roadside object, then count the seconds until the front of your vehicle reaches the same object
Counting from the moment the vehicle ahead passes a landmark until you reach it turns a gap you cannot judge in feet into a number of seconds.
-
33. An angry driver has cut in front of you and is now braking hard to provoke you. What is the safest response?
Show answer
Answer D: Drop back, avoid eye contact and let the driver go
Giving an aggressive driver space and no response removes the conflict, while any answering gesture invites escalation you cannot control in a heavy vehicle.
-
34. On the Interstate System, what are the federal maximums for a tandem axle group and for gross vehicle weight?
Show answer
Answer B: 34,000 pounds and 80,000 pounds
The federal Interstate limits allow 34,000 pounds on a tandem axle group and 80,000 pounds gross.
-
35. What blood alcohol concentration places an Idaho driver under the influence while operating a commercial vehicle?
Show answer
Answer A: .04 or more
Idaho law sets the commercial vehicle threshold at .04 or more, half of the .08 that applies to drivers 21 and older in other vehicles.
-
36. Why must the steering wheel be moved only a small amount at a time while backing?
Show answer
Answer B: Because a small turn of the wheel produces a large change at the rear of the vehicle
In reverse, the effect of the steering is greatly magnified at the back of the vehicle, so a small correction is usually all that is needed.
-
37. Which items belong to the trailer part of the walkaround inspection?
Show answer
Answer D: Landing gear, doors, tires, wheels, lights, reflectors, frame and cargo securement
The trailer has its own running gear, lighting, structure and load, and all of it is the responsibility of the driver pulling it.
-
38. What is the purpose of blocking placed against cargo on a trailer deck?
Show answer
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.
-
39. Loading heavy freight on top of lighter freight has what effect on the vehicle?
Show answer
Answer B: It raises the center of gravity and makes a rollover more likely
A high center of gravity lets the vehicle tip more easily in curves or during a sudden swerve.
-
40. Why is a quick lane change particularly risky with a load of hanging meat or of livestock?
Show answer
Answer A: The load swings or leans and can keep pushing the trailer after you straighten out
A swinging or leaning load keeps moving after the vehicle has finished the maneuver, so its momentum acts on the trailer at the worst moment.
-
41. What do the U-bolts on a leaf spring suspension do?
Show answer
Answer A: They clamp the spring assembly to the axle so it cannot move
U-bolts hold the spring pack tight against the axle, and a loose or broken U-bolt lets the axle slide out of place under load.
-
42. What makes a brake hose or air line a defect during the walkaround?
Show answer
Answer D: It is cracked, worn, kinked, or rubbing against another part
A chafed or cracked line can burst under pressure and take the braking on that circuit with it, so damage and rubbing points must be corrected.
-
43. A driver is tailgating you, honking and making gestures. What is the best response?
Show answer
Answer A: Do not make eye contact, ignore the gestures and give the driver room to get past
Engaging an aggressive driver only escalates the situation; the safest move is to stay calm, avoid eye contact and let the driver get by.
-
44. You are backing into a yard where electrical wires cross overhead. What is the main concern?
Show answer
Answer C: The wires may hang lower than the top of your vehicle
Overhead space has to be checked like any other space around the vehicle, because wires and cables are often lower than they look from the cab.
-
45. You must steer hard around an obstacle at highway speed. What is the correct technique?
Show answer
Answer B: Avoid braking while turning, turn only as far as needed, and countersteer as soon as the obstacle is passed
Braking during a hard steering input can lock the wheels and start a skid, and turning back at once keeps the vehicle from running off the far side of the road.
-
46. Your vehicle stalls on a railroad crossing and a train is coming. What should you do?
Show answer
Answer C: Get out at once and move toward the train, well off to one side
Leave the vehicle immediately and move at an angle toward the oncoming train, so that wreckage thrown forward by the impact travels away from you.
-
47. At 55 mph on dry pavement with good brakes, total stopping distance for a loaded heavy vehicle is roughly what?
Show answer
Answer B: About 400 feet or more
Perception, reaction, and braking together add up to roughly 400 feet or more, farther than the length of a football field.
-
48. Apart from the risk of stalling, why is rolling backwards when starting on an upgrade so serious in a heavy vehicle?
Show answer
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.
-
49. What color must the clearance and side marker lamps and reflectors at the front of a trailer be?
Show answer
Answer A: Amber
Amber marks the front and the forward part of the sides of a vehicle, while red marks the rear, so another driver can tell which way the vehicle is facing.
-
50. What must be true of the trailer landing gear before you move off?
Show answer
Answer B: Fully raised, with the crank handle secured and no missing or damaged parts
Landing gear left part way down can strike a railway crossing or a ramp, and a loose crank handle can swing out into a passing vehicle.