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Full CDL practice questions

Practice selected CDL topics. Some technical material uses older sources. Check current Illinois requirements before test day. Coverage and source limits

Illinois CDL Full practice questions

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Question 1 of 130
  1. 1. Before driving an interstate commercial truck, whose satisfaction with its safe operating condition is required even after a mechanic has worked on it?
  2. 2. The last required inspection report lists a repaired defect on the interstate truck you will drive. What does your required report signature acknowledge?
  3. 3. Under federal rules, may the driver-inspection reports for an interstate CMV be maintained electronically?
  4. 4. Before taking intermodal equipment onto the road in interstate service, what brake inspection does the driver rule describe?
  5. 5. An interstate truck tire has belt material exposed through a sidewall cut. What do federal tire rules permit?
  6. 6. What is the federal minimum major-groove tread depth for the front tires of an interstate truck?
  7. 7. For an interstate truck's rear tires, what is the federal minimum major-groove tread depth?
  8. 8. Which tires may not be fitted to the front wheels of an interstate commercial bus?
  9. 9. An interstate truck tire's cold pressure is below that specified for its load. What must happen before operation on that tire?
  10. 10. An interstate truck is not carrying hazardous materials and is not in a driveaway-towaway operation. Which extinguisher option meets the federal minimum rating?
  11. 11. An interstate power unit carries hazardous materials in a quantity requiring placards. What is its federal minimum extinguisher rating?
  12. 12. How must the required extinguisher be carried in an ordinary interstate commercial truck?
  13. 13. What must the required interstate-truck extinguisher allow you to determine visually?
  14. 14. Which is a complete federal reflective-warning-device option for an ordinary interstate truck?
  15. 15. An interstate CMV uses compressed gas as motor fuel. May it carry flame-producing emergency fusees?
  16. 16. Your interstate truck breaks down on a highway shoulder, not at a necessary traffic stop. What is required immediately?
  17. 17. An interstate truck stops on a rural highway shoulder where warning devices are required. When must they be placed?
  18. 18. Required triangles are available after an interstate truck breaks down. Can hazard flashers replace their placement?
  19. 19. An interstate truck stops on a straight divided-highway shoulder with no nearby sight obstruction. Where do the two farther warning devices go?
  20. 20. An interstate truck is stopped within 500 feet of a hillcrest hiding it from approaching drivers. How is the warning device toward that obstruction positioned?
  21. 21. During hours when lamps are not required, an interstate truck stops in a municipality's business district. What does the federal warning-device placement exception say?
  22. 22. On an interstate truck trip with accessible, unsealed cargo, when is the first in-trip cargo and securement inspection required?
  23. 23. After the initial inspection of accessible cargo on an interstate truck, which event triggers another check?
  24. 24. An interstate truck's cargo is sealed and the driver is ordered not to open it. Which statement correctly describes the inspection exception?
  25. 25. Boxes in an interstate truck cab block the driver's ready exit, although the road is visible. Is that acceptable?
  26. 26. The load is strapped down, but an interstate truck's tarpaulin and spare tire are unsecured. Is the truck ready under the cargo rule?
  27. 27. Under the general federal tiedown-count rule, an interstate truck carries a seven-foot article not blocked against forward movement. No special-purpose cargo exception applies. What minimum count is required?
  28. 28. An ordinary eight-foot article on an interstate truck is properly blocked against forward movement. Under the general tiedown-count rule, what minimum count applies?
  29. 29. Fog reduces visibility during interstate commercial operation. What does FMCSA's hazardous-weather guidance require?
  30. 30. Conditions have become too dangerous for your interstate truck to operate safely, and a safe stopping place is available. What should you do?
  31. 31. An interstate commercial bus is carrying passengers toward an at-grade railroad crossing with no applicable stop exception. Where is the required stop?
  32. 32. After its required railroad stop, an interstate manual-transmission passenger bus is ready to cross safely. What should the driver avoid during the crossing?
  33. 33. An interstate cargo tank is cleaned of hazardous residue and purged of vapors; hazardous-material placards and markings are no longer required or displayed. Under FMCSA's interpretation, does its past hazardous use alone trigger the 392.10(a)(4) railroad stop?
  34. 34. An interstate truck has a driver's seat belt. Does a short public-road trip remove the driver's belt duty?
  35. 35. An authorized passenger rides in a property-carrying interstate CMV equipped with the required passenger seat belt. Who must ensure the passenger uses it on public roads?
  36. 36. An interstate truck driver is temporarily stopped at a red light and wants to make a routine handheld call. Does that traffic stop remove the mobile-phone restriction?
  37. 37. An interstate driver must leave the normal belted driving position to reach a phone set to speaker mode. Is that compliant hands-free use while driving?
  38. 38. While driving an interstate CMV, a driver proposes to type a routine dispatch reply on the fleet's screen rather than a phone. Does the device's work purpose make this texting permissible?
  39. 39. An interstate CMV driver wants to read a routine text message while moving but will not type a reply. Is that outside FMCSA's texting definition?
  40. 40. An interstate truck has tires marked with a maximum speed of 55 mph under the federal speed-restricted-tire provision. The road limit is 65 mph. Which limit controls operation on those tires?
  41. 41. After pumping a hydraulic brake pedal, you hold steady pressure and the pedal slowly sinks. What is the appropriate response?
  42. 42. You must back a tall truck into an unfamiliar loading area. What should the preliminary walk-through include?
  43. 43. A helper will watch the blind area while you back toward a dock. What must you agree on before the truck moves?
  44. 44. In ordinary conditions, which scanning plan follows the CDL manual’s guidance for anticipating trouble ahead?
  45. 45. A car looks small and far away in your truck’s curved mirror. How should this affect a lane-change decision?
  46. 46. A loaded truck approaches a curve with a posted advisory speed commonly used by cars. What is the safest plan?
  47. 47. Your headlights reveal less clear roadway than the distance your truck needs to stop. What adjustment is needed?
  48. 48. Under good conditions, a 40-foot commercial vehicle is traveling at 55 mph. What following interval matches the manual’s length-and-speed guideline?
  49. 49. The truck starts to hydroplane across standing water. Which response helps the tires regain contact?
  50. 50. On a near-freezing day, your truck approaches a bridge from a road that is still wet. What should you allow for?
  51. 51. You are approaching an icy stretch with the retarder switched on. What does the CDL manual recommend?
  52. 52. After a long drive on a hot day, a properly inflated tire shows a higher pressure than its cold reading. Should you bleed air to restore the cold reading?
  53. 53. Your loaded truck is about to descend a long, steep grade. When should you select the suitable low gear?
  54. 54. A traffic queue beyond a railroad crossing leaves room for the tractor but not the entire trailer. What should you do?
  55. 55. On a slippery curve, the truck keeps sliding straight despite your steering input. What is the useful response?
  56. 56. A driver is struggling to stay awake and considers taking a stimulant to finish the delivery. What is the sound safety decision?
  57. 57. A cold medicine is sold without a prescription, but its label warns of drowsiness. What should a commercial driver understand?
  58. 58. Two loads have the same weight. One stacks the heaviest freight high; the other puts it low. Which arrangement better resists rollover?
  59. 59. A load places too little weight on the truck’s steering axle. What operating problem can result?
  60. 60. You cannot open a sealed freight container at pickup. Does its seal make gross-weight and axle-weight checks unnecessary?
  61. 61. A heavy crate can slide sideways even though it cannot move toward the cab. Is the securement problem solved?
  62. 62. A flatbed has a front-end header board behind the cab. Which cargo movement is it intended to help resist?
  63. 63. An air-brake system reaches its normal upper pressure and stops pumping air into the reservoirs. Which component controls this cut-out and later cut-in?
  64. 64. Why is removing accumulated moisture from air reservoirs especially important before freezing weather?
  65. 65. Before moving an air-braked truck, you check its supply-pressure gauges. What do they tell you?
  66. 66. The low-air warning activates while the truck is moving. What is the safe response?
  67. 67. What keeps a typical spring parking brake released while the truck is being driven?
  68. 68. On a system without protection against brake compounding, what can happen if you press the service pedal while the spring brakes are already applied?
  69. 69. One circuit of a dual air-brake system loses pressure, while the other still has air. What does this mean for the trip?
  70. 70. An automatic slack adjuster is repeatedly found out of adjustment. What is the appropriate approach?
  71. 71. In a clear, safe test area, how should you check whether the applied parking brake holds the truck?
  72. 72. During a slow, controlled service-brake check, the truck pulls sharply to one side. What does that suggest?
  73. 73. Your truck’s ABS is working during a hard stop. How should you use the brake pedal?
  74. 74. Why does the stopping-distance calculation for air brakes include an extra distance after the pedal is pressed?
  75. 75. A tractor clears a curb during a slow turn, but the trailer’s rear wheels are still approaching it. What must the driver allow for?
  76. 76. A sudden steering move travels through a tractor pulling two trailers. Which trailer is especially vulnerable to the amplified whipping motion?
  77. 77. You are driving the tractor without a trailer. Should its lighter weight make you assume it will stop more quickly?
  78. 78. In your mirror, the trailer begins swinging sideways because its wheels have locked during braking. What helps restore its path?
  79. 79. A driver proposes using the trailer hand valve to hold a parked rig while leaving the cab. Why is that unsafe?
  80. 80. A trailer air line tears apart after a breakaway. Which protection is intended to keep the leak from draining all air out of the tractor?
  81. 81. One trailer air line supplies the trailer reservoirs and controls emergency braking if its pressure is lost. Which line performs these functions?
  82. 82. After coupling a spring-braked trailer, you discover that its service and supply air lines were crossed. What problem can this cause?
  83. 83. Before backing the tractor under a semitrailer, how should its front height relate to the fifth wheel?
  84. 84. A gentle coupling pull-test seems satisfactory. During the visual check, the jaws appear around the kingpin head instead of its shank. May you depart?
  85. 85. A coupled trailer’s landing feet are a few inches above the ground. What remains necessary before departure?
  86. 86. While uncoupling, why do you pause with the tractor frame still beneath the trailer after the fifth wheel has cleared?
  87. 87. You are assembling a set of two trailers with substantially different loaded weights. Which order does the manual recommend for the safest handling?
  88. 88. You are choosing a rest-area parking space for a set of doubles. Which feature deserves special consideration?
  89. 89. A set of doubles is ready for travel. How should the service and supply shut-off valves at the rear of each trailer be positioned?
  90. 90. During a properly secured air-continuity check, no air escapes when you briefly open the final trailer’s service-line valve with the service control applied. What should you do?
  91. 91. The converter dolly’s eye is resting in the front trailer’s pintle hook. What additional connection checks are still necessary?
  92. 92. A helper reaches for the pintle-hook latch while the dolly is still supporting the rear trailer. What is the concern?
  93. 93. A tank shell looks intact, but liquid is seeping around a discharge-valve connection. Is the vehicle ready to haul the load?
  94. 94. A partially filled liquid tanker has just stopped on ice. Why can the vehicle still be pushed forward?
  95. 95. Your tanker has separate compartments divided by solid bulkheads. What must you consider when deciding which compartments to fill or empty?
  96. 96. A driver says that tank baffles make abrupt lane changes safe because they control liquid movement. What is wrong with that reasoning?
  97. 97. You change from a baffled tanker to a smooth-bore tanker. What handling change should you particularly anticipate?
  98. 98. A dispatcher asks you to fill every available gallon of a cargo tank with liquid. What must determine the actual loading amount?
  99. 99. A passenger wants to leave a suitcase in the aisle beside an emergency exit because the ride is short. What should you require?
  100. 100. Before carrying passengers, you find an emergency door that does not close securely. What is the appropriate conclusion?
  101. 101. A bus passes its exterior walk-around, but a passenger seat is loose and a handhold is damaged. Is the passenger-area inspection complete?
  102. 102. A passenger has just boarded your transit bus and is still finding a secure position. When should you begin moving?
  103. 103. A disruptive adult passenger is making continued bus operation unsafe. Which response follows the manual’s safety guidance?
  104. 104. You signal to leave a bus stop, but nearby traffic has not made room. What is the safe assumption?
  105. 105. A disabled bus must be towed, and passengers can safely get off first. What is the manual’s guidance?
  106. 106. Opening a transit bus door activates a brake-door interlock. Can that device replace the parking brake when securing the bus?
  107. 107. A child is close to the front bumper below the driver’s direct view. Which school-bus mirrors are specifically intended to help check this danger zone?
  108. 108. You counted a child at the stop, but cannot account for that child after the others board. What should happen before the bus moves?
  109. 109. What should students be taught to do if they drop an item beside the bus during unloading?
  110. 110. The final school-bus stop is complete and the bus sounds empty. What check should still be made at the end of the route?
  111. 111. After stopping a school bus at a railroad crossing, how can you improve the check for an approaching train?
  112. 112. A school bus stalls on the tracks and a train is approaching. What direction should evacuated students move?
  113. 113. While children are unloading, two students inside begin arguing. What should remain your immediate focus?
  114. 114. At an approved drop-off maneuver, backing is unavoidable and no safer option exists. Should students get off before or after the bus backs?
  115. 115. A school bus is parked close to a roadside object. As the driver steers away, why must the rear overhang be watched in the mirrors?
  116. 116. Strong gusts are pushing a school bus sideways. What is the manual’s recommended response?
  117. 117. A shipment is subject to hazardous-materials shipping-paper requirements, but the shipper says the paperwork will be emailed after you leave. What should you do?
  118. 118. You leave the controls of a truck carrying a hazardous-materials shipment that requires shipping papers. Where should those papers remain?
  119. 119. The correct hazard placard is attached, but a loose tarp covers its lower half. What needs to happen before travel?
  120. 120. Hazardous-material drums cannot slide out of the trailer, but they can strike one another and damage their fittings. Is that adequate securement?
  121. 121. A hazardous-material package bears required orientation arrows. A loader wants to lay it on its side to fit another pallet. What is the correct response?
  122. 122. Before workers begin loading hazardous material into a motor vehicle, what must the driver ensure about the vehicle itself?
  123. 123. Class 3 flammable liquid is being unloaded and a person approaches the transfer area with a lighted cigarette. What is the necessary safety response?
  124. 124. You stop to fuel the power unit of a truck carrying placarded hazardous material. Which arrangement is correct?
  125. 125. A placarded load can use a practical, permitted route around a crowded downtown area. What does the manual's safety guidance advise if going downtown would only be more convenient?
  126. 126. At pickup, you notice liquid escaping from a hazardous-material package. The shipper offers to place it on an absorbent pad. What is the proper decision?
  127. 127. Emergency responders need to identify a load’s hazards quickly. Which shipping-paper information is especially useful for finding the relevant Emergency Response Guidebook entry?
  128. 128. An unknown substance appears to be leaking from hazardous-material cargo. Should you approach and smell it to identify the chemical?
  129. 129. You suspect a hazardous-material cargo fire and the closed trailer doors are hot. What is the appropriate action?
  130. 130. Hazardous material is leaking from your stopped vehicle. A truck stop with a telephone is several miles away. Should you continue there to get help?
Review all 130 questions with answers

  1. Before driving an interstate commercial truck, whose satisfaction with its safe operating condition is required even after a mechanic has worked on it?

    Correct answer: The driver's

    A repair visit does not remove the driver's pre-driving duty to be satisfied that the vehicle is safe.

    Source: 49 CFR 396.13(a); interstate CMV scope ↗

  2. The last required inspection report lists a repaired defect on the interstate truck you will drive. What does your required report signature acknowledge?

    Correct answer: Your review and the certification of required repairs

    The signature acknowledges review of the report and the repair certification; it is not a claim that the driver acted as mechanic.

    Source: 49 CFR 396.13(b)–(c); same vehicle, not a detached towed unit; interstate CMV scope ↗

  3. Under federal rules, may the driver-inspection reports for an interstate CMV be maintained electronically?

    Correct answer: Yes, under the electronic-record requirements

    Section 396.13(d) permits electronic reports in accordance with 49 CFR 390.32.

    Source: 49 CFR 396.13(d), cross-reference 390.32; interstate CMV scope ↗

  4. Before taking intermodal equipment onto the road in interstate service, what brake inspection does the driver rule describe?

    Correct answer: A thorough visible-component check without crawling underneath

    The intermodal inspection covers readily visible service-brake components and trailer connections, without requiring the driver to physically go underneath.

    Source: 49 CFR 392.7(b), service-brake-components bullet; interstate CMV scope ↗

  5. An interstate truck tire has belt material exposed through a sidewall cut. What do federal tire rules permit?

    Correct answer: Do not operate the vehicle on that tire

    Exposed ply or belt material is a prohibited tire condition, independent of tread depth.

    Source: 49 CFR 393.75(a)(1),(4); interstate CMV scope ↗

  6. What is the federal minimum major-groove tread depth for the front tires of an interstate truck?

    Correct answer: 4/32 inch

    Measure in a major groove, not at tie bars, humps or fillets; front truck tires require at least 4/32 inch.

    Source: 49 CFR 393.75(b); interstate CMV scope ↗

  7. For an interstate truck's rear tires, what is the federal minimum major-groove tread depth?

    Correct answer: 2/32 inch

    The general non-front-position minimum is 2/32 inch, measured away from tie bars, humps and fillets.

    Source: 49 CFR 393.75(c), contrasted with (b); interstate CMV scope ↗

  8. Which tires may not be fitted to the front wheels of an interstate commercial bus?

    Correct answer: Regrooved, recapped or retreaded tires

    The federal front-wheel prohibition specifically applies to buses and these three tire categories.

    Source: 49 CFR 393.75(d); interstate CMV scope ↗

  9. An interstate truck tire's cold pressure is below that specified for its load. What must happen before operation on that tire?

    Correct answer: Correct the underinflation for the load

    Federal rules prohibit operation with cold tire pressure below that specified for the carried load.

    Source: 49 CFR 393.75(i)(1); interstate CMV scope ↗

  10. An interstate truck is not carrying hazardous materials and is not in a driveaway-towaway operation. Which extinguisher option meets the federal minimum rating?

    Correct answer: One rated at least 5 B:C

    One 5 B:C extinguisher or two extinguishers each rated at least 4 B:C meet the stated non-hazmat rating option.

    Source: 49 CFR 393.95 opening scope; (a)(1)(ii),(a)(6); interstate CMV scope ↗

  11. An interstate power unit carries hazardous materials in a quantity requiring placards. What is its federal minimum extinguisher rating?

    Correct answer: 10 B:C

    A power unit transporting placardable hazardous materials requires an extinguisher rated at least 10 B:C.

    Source: 49 CFR 393.95(a)(1)(i); interstate CMV scope ↗

  12. How must the required extinguisher be carried in an ordinary interstate commercial truck?

    Correct answer: Readily accessible and securely mounted

    It must be filled, accessible, and mounted against sliding, rolling or vertical movement.

    Source: 49 CFR 393.95(a)(4); interstate CMV scope ↗

  13. What must the required interstate-truck extinguisher allow you to determine visually?

    Correct answer: Whether it is fully charged

    The extinguisher must permit visual determination of its charged condition.

    Source: 49 CFR 393.95(a)(3); interstate CMV scope ↗

  14. Which is a complete federal reflective-warning-device option for an ordinary interstate truck?

    Correct answer: Three compliant bidirectional reflective triangles

    Three triangles conforming to FMVSS 125 are a listed option; personal visibility gear does not replace a required device.

    Source: 49 CFR 393.95(f)(1),(3); interstate CMV scope ↗

  15. An interstate CMV uses compressed gas as motor fuel. May it carry flame-producing emergency fusees?

    Correct answer: No; this vehicle is within the prohibition

    Section 393.95(g) prohibits carrying flame signals on a CMV using compressed gas as fuel.

    Source: 49 CFR 393.95(g); interstate CMV scope ↗

  16. Your interstate truck breaks down on a highway shoulder, not at a necessary traffic stop. What is required immediately?

    Correct answer: Activate its hazard warning flashers

    Flashers are the immediate signal; warning-device placement is a separate duty.

    Source: 49 CFR 392.22(a); interstate CMV scope ↗

  17. An interstate truck stops on a rural highway shoulder where warning devices are required. When must they be placed?

    Correct answer: As soon as possible, within ten minutes

    Ten minutes is the outer limit, not a routine waiting period.

    Source: 49 CFR 392.22(b)(1); no (b)(2) exception in scenario; interstate CMV scope ↗

  18. Required triangles are available after an interstate truck breaks down. Can hazard flashers replace their placement?

    Correct answer: No; flashers are not a substitute for required devices

    The rule permits flashers in addition to, not instead of, required warning devices.

    Source: 49 CFR 392.22(a), final sentence; interstate CMV scope ↗

  19. An interstate truck stops on a straight divided-highway shoulder with no nearby sight obstruction. Where do the two farther warning devices go?

    Correct answer: 100 and 200 feet toward approaching traffic

    The divided-road arrangement puts the farther devices toward approaching traffic; another goes on the traffic side within ten feet of the rear.

    Source: 49 CFR 392.22(b)(2)(v); unobstructed divided-road scenario; interstate CMV scope ↗

  20. An interstate truck is stopped within 500 feet of a hillcrest hiding it from approaching drivers. How is the warning device toward that obstruction positioned?

    Correct answer: 100–500 feet from the truck to provide ample warning

    A nearby hill, curve or obstruction changes placement of the warning signal in that direction.

    Source: 49 CFR 392.22(b)(2)(iv); interstate CMV scope ↗

  21. During hours when lamps are not required, an interstate truck stops in a municipality's business district. What does the federal warning-device placement exception say?

    Correct answer: Placement is not required by that provision

    The municipal business/residential exception concerns device placement; it does not cancel other applicable duties such as flashers.

    Source: 49 CFR 392.22(b)(2)(iii), with (a) distinguished; interstate CMV scope ↗

  22. On an interstate truck trip with accessible, unsealed cargo, when is the first in-trip cargo and securement inspection required?

    Correct answer: Within the first 50 miles

    The first in-trip inspection must occur within 50 miles, with necessary adjustments made.

    Source: 49 CFR 392.9(b)(2),(4); interstate CMV scope ↗

  23. After the initial inspection of accessible cargo on an interstate truck, which event triggers another check?

    Correct answer: A duty change, 3 driving hours or 150 miles—whichever is first

    The three triggers operate independently; discovered looseness is not a prerequisite.

    Source: 49 CFR 392.9(b)(3)(i)–(iii),(4); interstate CMV scope ↗

  24. An interstate truck's cargo is sealed and the driver is ordered not to open it. Which statement correctly describes the inspection exception?

    Correct answer: Cargo checks are exempt; safe loading is not

    The specified inspection exception does not erase paragraph (a)'s general cargo and equipment conditions.

    Source: 49 CFR 392.9(a),(b)(4); interstate CMV scope ↗

  25. Boxes in an interstate truck cab block the driver's ready exit, although the road is visible. Is that acceptable?

    Correct answer: No; cargo must not block ready exit from the cab

    Unobstructed vision alone is insufficient; cargo must also preserve movement, emergency access and ready exit.

    Source: 49 CFR 392.9(a)(3), ordinary truck not self-steer dolly; interstate CMV scope ↗

  26. The load is strapped down, but an interstate truck's tarpaulin and spare tire are unsecured. Is the truck ready under the cargo rule?

    Correct answer: No; these items must also be secured

    The rule separately requires securement of tarpaulins, spare tires and other operating equipment.

    Source: 49 CFR 392.9(a)(2); interstate CMV scope ↗

  27. Under the general federal tiedown-count rule, an interstate truck carries a seven-foot article not blocked against forward movement. No special-purpose cargo exception applies. What minimum count is required?

    Correct answer: Two tiedowns

    An article longer than five feet and no longer than ten feet requires at least two in this situation; other securement requirements still apply.

    Source: 49 CFR 393.110(a),(b)(2)(ii),(d); interstate CMV scope ↗

  28. An ordinary eight-foot article on an interstate truck is properly blocked against forward movement. Under the general tiedown-count rule, what minimum count applies?

    Correct answer: One tiedown

    Forward blocking invokes at least one tiedown per ten feet or fraction. Strength and other securement requirements still apply.

    Source: 49 CFR 393.110(a),(c),(d); no special-purpose exception; interstate CMV scope ↗

  29. Fog reduces visibility during interstate commercial operation. What does FMCSA's hazardous-weather guidance require?

    Correct answer: Reduce speed and exercise extreme caution

    The guidance calls for speed reduction when conditions impair visibility or traction.

    Source: FMCSA > Safety Planner 6.3.10, first paragraph; 392.14 guidance; HTML reviewed September 12, 2026 ↗

  30. Conditions have become too dangerous for your interstate truck to operate safely, and a safe stopping place is available. What should you do?

    Correct answer: Stop operating until it can be done safely

    FMCSA guidance calls for discontinuing unsafe operation. The scenario supplies a safe place to stop rather than creating a new roadside hazard.

    Source: FMCSA > Safety Planner 6.3.10, both substantive paragraphs; HTML reviewed September 12, 2026 ↗

  31. An interstate commercial bus is carrying passengers toward an at-grade railroad crossing with no applicable stop exception. Where is the required stop?

    Correct answer: 15–50 feet from the nearest rail

    FMCSA's railroad guidance specifies the 15–50-foot range, with looking and listening before a safe crossing.

    Source: FMCSA > Safety Planner 6.3.9; 392.10(a), exceptions acknowledged; HTML reviewed September 12, 2026 ↗

  32. After its required railroad stop, an interstate manual-transmission passenger bus is ready to cross safely. What should the driver avoid during the crossing?

    Correct answer: Shifting gears on the tracks

    FMCSA's crossing guidance prohibits gear changes while the vehicle crosses the tracks.

    Source: FMCSA > Safety Planner 6.3.9, gear-change sentence; specified stopping-required vehicle; HTML reviewed September 12, 2026 ↗

  33. An interstate cargo tank is cleaned of hazardous residue and purged of vapors; hazardous-material placards and markings are no longer required or displayed. Under FMCSA's interpretation, does its past hazardous use alone trigger the 392.10(a)(4) railroad stop?

    Correct answer: No; this cleaned-and-purged case qualifies

    The interpretation requires the specified conditions. It is not an exemption from crossing signals or other applicable stopping duties.

    Source: FMCSA > 392.10 Guidance Q&A 1, complete response; issued/effective February 28, 2020; HTML reviewed September 12, 2026 ↗

  34. An interstate truck has a driver's seat belt. Does a short public-road trip remove the driver's belt duty?

    Correct answer: No; properly use the belt

    FMCSA's guidance requires driver belt use on short trips as well as long ones.

    Source: FMCSA > TIP #1: Always Wear Your Safety Belt; discussion of 392.16; HTML reviewed September 12, 2026 ↗

  35. An authorized passenger rides in a property-carrying interstate CMV equipped with the required passenger seat belt. Who must ensure the passenger uses it on public roads?

    Correct answer: The motor carrier and driver

    FMCSA's passenger-belt rule places responsibility on the carrier and driver, not solely on the passenger.

    Source: FMCSA > Final rule 2016-13099, Summary; 392.16(b) property-carrying scope; HTML reviewed September 12, 2026 ↗

  36. An interstate truck driver is temporarily stopped at a red light and wants to make a routine handheld call. Does that traffic stop remove the mobile-phone restriction?

    Correct answer: No; momentary traffic stops remain covered

    The rule covers temporary stops caused by traffic and traffic-control devices.

    Source: FMCSA > What does this rule mean to drivers and carriers? > temporarily stationary; routine call; HTML reviewed September 12, 2026 ↗

  37. An interstate driver must leave the normal belted driving position to reach a phone set to speaker mode. Is that compliant hands-free use while driving?

    Correct answer: No; unsafe reaching is still prohibited

    The phone must be within reach from the normal, properly restrained driving position.

    Source: FMCSA > Definition of using a mobile telephone; Compliance; HTML reviewed September 12, 2026 ↗

  38. While driving an interstate CMV, a driver proposes to type a routine dispatch reply on the fleet's screen rather than a phone. Does the device's work purpose make this texting permissible?

    Correct answer: No; texting on a dispatch device is also prohibited

    FMCSA expressly includes texting on dispatch devices; the hardware's business purpose does not create an exception.

    Source: FMCSA > What does this rule mean to you? > dispatching devices; routine non-emergency message; HTML reviewed September 12, 2026 ↗

  39. An interstate CMV driver wants to read a routine text message while moving but will not type a reply. Is that outside FMCSA's texting definition?

    Correct answer: No; reading electronic text messages is included

    FMCSA's definition includes reading text as well as manually entering it.

    Source: FMCSA > What exactly is Texting?; routine non-emergency text message; HTML reviewed September 12, 2026 ↗

  40. An interstate truck has tires marked with a maximum speed of 55 mph under the federal speed-restricted-tire provision. The road limit is 65 mph. Which limit controls operation on those tires?

    Correct answer: Do not exceed the tires' 55-mph rating

    Section 393.75(f) prohibits exceeding the rated limit of the specified speed-restricted tires.

    Source: 49 CFR 393.75(f), tires labeled maximum speed 55 mph or less under FMVSS 119 S6.5(e); interstate CMV scope ↗

  41. After pumping a hydraulic brake pedal, you hold steady pressure and the pedal slowly sinks. What is the appropriate response?

    Correct answer: Have the possible hydraulic leak or other brake problem corrected before driving.

    The manual describes holding the pedal after pumping it as a hydraulic leak check. A moving pedal during the hold indicates a problem that must be corrected.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.1.5 Seven-step Inspection Method, Step 7 - Test for Hydraulic Leaks; printed page 2-7, physical PDF page 29. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  42. You must back a tall truck into an unfamiliar loading area. What should the preliminary walk-through include?

    Correct answer: Ground-level obstacles, side clearance, and overhead clearance along the entire path.

    Before backing, get out and inspect the path. A clear pavement surface does not establish clearance from branches, wires, canopies, or side obstructions.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.2.4 Backing Safely - Look at Your Path; printed page 2-8, physical PDF page 30. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  43. A helper will watch the blind area while you back toward a dock. What must you agree on before the truck moves?

    Correct answer: Clear hand signals, especially the signal that means stop.

    A helper supplements the driver’s checks. Agreed signals, particularly a stop signal, prevent confusion during backing.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.2.4 Backing Safely - Use a Helper; printed page 2-8, physical PDF page 30. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  44. In ordinary conditions, which scanning plan follows the CDL manual’s guidance for anticipating trouble ahead?

    Correct answer: Look about 12 to 15 seconds ahead while also checking nearer traffic and the mirrors.

    The manual recommends a 12-to-15-second look-ahead range. It is a scanning guide, not a reason to ignore nearby hazards or mirrors.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.4.1 Seeing Ahead; printed page 2-10, physical PDF page 32. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  45. A car looks small and far away in your truck’s curved mirror. How should this affect a lane-change decision?

    Correct answer: Allow for the mirror making objects appear smaller and farther away than they are.

    Convex mirrors expand the field of view but distort apparent size and distance. Use the complete mirror-check routine and a genuinely safe gap.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.4.2 Seeing to the Sides and Rear - How to Use Mirrors; printed page 2-11, physical PDF page 33. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  46. A loaded truck approaches a curve with a posted advisory speed commonly used by cars. What is the safest plan?

    Correct answer: Reduce speed before entering; the posted curve speed may still be too fast for the truck.

    A truck’s load and center of gravity affect its safe curve speed. Slow before the curve instead of relying on a speed suitable for a passenger car.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.6.3 Speed and Curves; printed page 2-15, physical PDF page 37. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  47. Your headlights reveal less clear roadway than the distance your truck needs to stop. What adjustment is needed?

    Correct answer: Slow enough to stop within the roadway you can see is clear.

    Do not drive faster than the available sight distance permits. Darkness, hills, curves, and weather can all shorten the clear distance ahead.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.6.4 Speed and Distance Ahead; printed page 2-15, physical PDF page 37. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  48. Under good conditions, a 40-foot commercial vehicle is traveling at 55 mph. What following interval matches the manual’s length-and-speed guideline?

    Correct answer: At least five seconds.

    The manual recommends one second per 10 feet of vehicle length below 40 mph, plus one additional second above 40 mph. Forty feet at 55 mph gives five seconds; adverse conditions require more.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.7.1 Space Ahead; printed page 2-16, physical PDF page 38. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  49. The truck starts to hydroplane across standing water. Which response helps the tires regain contact?

    Correct answer: Release the accelerator and avoid braking while the tires regain road contact.

    The older technical guide advises releasing the accelerator rather than braking during hydroplaning; on a manual-transmission vehicle it also says to disengage the clutch. Let the vehicle slow and restore tire contact instead of using abrupt inputs.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.6.2 Matching Speed to the Road Surface - Hydroplaning; printed pages 2-14, 2-15, physical PDF pages 36, 37. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  50. On a near-freezing day, your truck approaches a bridge from a road that is still wet. What should you allow for?

    Correct answer: The bridge may be icy even though nearby pavement is only wet.

    Bridges can freeze before other road surfaces, and ice may not be obvious. Make smooth control inputs and reduce speed before reaching a suspect surface.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.6.2 Matching Speed to the Road Surface - Bridges; printed page 2-14, physical PDF page 36. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  51. You are approaching an icy stretch with the retarder switched on. What does the CDL manual recommend?

    Correct answer: Turn the retarder off when traction is poor.

    Retarders act through the drive wheels and can cause a skid on slippery surfaces. The manual advises turning them off in poor-traction conditions.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.3.4 Retarders; printed pages 2-9, 2-10, physical PDF pages 31, 32. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  52. After a long drive on a hot day, a properly inflated tire shows a higher pressure than its cold reading. Should you bleed air to restore the cold reading?

    Correct answer: No; normal heating raises pressure, and bleeding air can leave the tire underinflated when it cools.

    Do not let air out of hot tires simply because their pressure has risen. If a tire is excessively hot, stop safely and let it cool while addressing the cause.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.14.1 Vehicle Checks - Tires; printed page 2-29, physical PDF page 51. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  53. Your loaded truck is about to descend a long, steep grade. When should you select the suitable low gear?

    Correct answer: Before starting down the grade, while speed is under control.

    Plan the safe speed and gear before descending. Engine braking should carry much of the speed-control load; late downshifting can fail when engine speed is too high.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.16.2 Select the Right Gear Before Starting Down the Grade; printed page 2-32, physical PDF page 54. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  54. A traffic queue beyond a railroad crossing leaves room for the tractor but not the entire trailer. What should you do?

    Correct answer: Wait before the tracks until the whole combination can clear them without stopping.

    The entire vehicle must be able to get across and clear the tracks. Never enter a crossing when congestion may trap part of the combination on it.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.15.5 Crossing the Tracks; printed page 2-31, physical PDF page 53. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  55. On a slippery curve, the truck keeps sliding straight despite your steering input. What is the useful response?

    Correct answer: Reduce the demand on the front tires and slow down so they can regain traction.

    A front-wheel skid means the front tires lack traction to steer. More steering does not restore that traction; reduce the cause of the skid and slow the vehicle.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.19.3 Front-wheel Skids; printed page 2-37, physical PDF page 59. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  56. A driver is struggling to stay awake and considers taking a stimulant to finish the delivery. What is the sound safety decision?

    Correct answer: Stop safely and rest rather than use a drug to hide fatigue.

    The manual warns against masking fatigue with drugs. Rest addresses fatigue; temporary alertness tricks do not make a tired driver reliably safe.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.11.2 Driver Factors - Fatigue and Lack of Alertness, continued; printed page 2-26, physical PDF page 48. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  57. A cold medicine is sold without a prescription, but its label warns of drowsiness. What should a commercial driver understand?

    Correct answer: Nonprescription medicine can still impair safe driving.

    Legal medicines, including cold remedies, can affect alertness and safe operation. Follow warnings and appropriate medical advice rather than treating nonprescription status as proof of safety.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.22.2 Other Drugs; printed pages 2-41, 2-42, physical PDF pages 63, 64. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  58. Two loads have the same weight. One stacks the heaviest freight high; the other puts it low. Which arrangement better resists rollover?

    Correct answer: The arrangement with the heaviest freight kept low.

    Keeping heavy cargo low lowers the center of gravity. Weight distribution affects stability even when total vehicle weight does not change.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 3.2.3 Don't Be Top-heavy; printed page 3-2, physical PDF page 68. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  59. A load places too little weight on the truck’s steering axle. What operating problem can result?

    Correct answer: The front tires may have too little traction for safe steering.

    An underloaded front axle can make steering unsafe. Balance cargo so neither total weight nor individual axle loading creates a control problem.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 3.2.4 Balance the Weight; printed page 3-2, physical PDF page 68. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  60. You cannot open a sealed freight container at pickup. Does its seal make gross-weight and axle-weight checks unnecessary?

    Correct answer: No; the loaded gross and axle weights still need checking.

    A container seal does not measure the load or establish suitable weight distribution. The guide retains gross-weight and axle-weight checks for sealed loads. This question supplies no current numerical Iowa weight limit or permit exception.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 3.3.5 Sealed and Containerized Loads; printed page 3-3, physical PDF page 69. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  61. A heavy crate can slide sideways even though it cannot move toward the cab. Is the securement problem solved?

    Correct answer: No; the load must also be protected against other movement during transport.

    Blocking and bracing keep cargo from shifting in directions that can damage the vehicle or affect control. Preventing movement in one direction alone may be inadequate.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 3.3.1 Blocking and Bracing; printed page 3-2, physical PDF page 68. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  62. A flatbed has a front-end header board behind the cab. Which cargo movement is it intended to help resist?

    Correct answer: Cargo moving forward during a sudden stop or crash.

    A header board helps protect the cab from freight shifting forward. It does not eliminate the need for proper securement of the whole load.

    Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 3.3.3 Header Boards; printed page 3-3, physical PDF page 69. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗

  63. An air-brake system reaches its normal upper pressure and stops pumping air into the reservoirs. Which component controls this cut-out and later cut-in?

    Correct answer: The air-compressor governor.

    The compressor produces compressed air, while the governor controls when the compressor pumps air into the reservoirs.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 5.1.1 Air Compressor and 5.1.2 Air Compressor Governor; printed 5-1, physical PDF page 75. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  64. Why is removing accumulated moisture from air reservoirs especially important before freezing weather?

    Correct answer: Water can freeze and interfere with brake operation.

    Compressed air can carry water and oil into reservoirs. The manual calls for daily draining of manually drained tanks because water can freeze and cause brake failure.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 5.1.4 Air Tank Drains; printed 5-1, physical PDF page 75. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  65. Before moving an air-braked truck, you check its supply-pressure gauges. What do they tell you?

    Correct answer: How much air pressure is stored in the reservoirs.

    Supply gauges show reservoir pressure. An application-pressure gauge, when fitted, serves a different purpose by showing pressure being applied to the brakes.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 5.1.9 Supply Pressure Gauges and 5.1.10 Application Pressure Gauge; continued on physical PDF page 77; printed 5-2–5-3, physical PDF page 76. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  66. The low-air warning activates while the truck is moving. What is the safe response?

    Correct answer: Stop safely as soon as possible and correct the cause instead of waiting for automatic spring-brake application.

    Low air means braking capability is in danger. The manual directs a prompt safe stop while you still have control; do not wait for further pressure loss.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 5.4.7 Low Air Pressure; printed 5-9, physical PDF page 83. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  67. What keeps a typical spring parking brake released while the truck is being driven?

    Correct answer: Air pressure holding back the powerful spring.

    Spring brakes apply mechanically when their hold-off air is removed. Air pressure holds the spring back during normal released operation.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 5.1.14 Spring Brakes; printed 5-3, physical PDF page 77. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  68. On a system without protection against brake compounding, what can happen if you press the service pedal while the spring brakes are already applied?

    Correct answer: Combined spring and air forces can damage the brakes.

    The manual warns that service-brake force added to applied spring-brake force can damage components. Know the controls and protective features of the vehicle you operate.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 5.1.15 Parking Brake Controls, compounding caution; printed 5-3, physical PDF page 77. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  69. One circuit of a dual air-brake system loses pressure, while the other still has air. What does this mean for the trip?

    Correct answer: Braking is reduced; stop safely and have the system repaired.

    A dual system separates circuits but does not make a circuit failure harmless. The remaining brakes may not stop the vehicle normally.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 5.2 Dual Air Brake; printed 5-5, physical PDF page 79. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  70. An automatic slack adjuster is repeatedly found out of adjustment. What is the appropriate approach?

    Correct answer: Have qualified personnel find and repair the underlying problem.

    Repeated manual adjustment can hide an underlying mechanical defect. The manual directs attention to proper repair, not recurring adjustment as a substitute.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 5.3.2 During Step 5 Walk-around Inspection, automatic slack adjusters; printed 5-6, physical PDF page 80. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  71. In a clear, safe test area, how should you check whether the applied parking brake holds the truck?

    Correct answer: Use a low gear and pull gently against the applied brake.

    A gentle pull in low gear checks holding ability without an aggressive movement. This knowledge item does not replace an examiner-supervised skills inspection.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 5.3.3 Step 7 Final Air Brake Check, Test Parking Brake; printed 5-7, physical PDF page 81. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  72. During a slow, controlled service-brake check, the truck pulls sharply to one side. What does that suggest?

    Correct answer: A possible brake problem that needs attention before normal travel.

    The manual’s low-speed service-brake check looks for pulling, unusual feel, or delayed action. An abnormal result must not be dismissed.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 5.3.3 Step 7 Final Air Brake Check, Test Service Brakes; printed 5-7, physical PDF page 81. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  73. Your truck’s ABS is working during a hard stop. How should you use the brake pedal?

    Correct answer: Apply the braking force needed to stop safely and remain in control.

    ABS manages impending wheel lock automatically. It helps preserve control but does not guarantee a shorter stop or excuse unsafe speed and spacing.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 5.4.2 Braking with Antilock Brakes; printed 5-8, physical PDF page 82. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  74. Why does the stopping-distance calculation for air brakes include an extra distance after the pedal is pressed?

    Correct answer: Air takes time to travel through the system and operate the brakes.

    Brake lag is the interval between the driver’s application and effective braking. It adds to perception, reaction, and braking distances.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 5.4.4 Stopping Distance; printed 5-8, physical PDF page 82. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  75. A tractor clears a curb during a slow turn, but the trailer’s rear wheels are still approaching it. What must the driver allow for?

    Correct answer: The rear wheels track inside the path of the front wheels.

    Offtracking makes the trailer wheels follow a shorter, inside path. Plan a safe turn that provides room for the whole vehicle without creating a squeeze hazard.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 6.1.6 Turn Wide; printed 6-3, physical PDF page 87. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  76. A sudden steering move travels through a tractor pulling two trailers. Which trailer is especially vulnerable to the amplified whipping motion?

    Correct answer: The last trailer.

    Rearward amplification can make the last trailer move much more severely than the tractor. Smooth, planned steering reduces this rollover hazard.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 6.1.2 Steer Gently and 7.1.2 Beware of the Crack-the-whip Effect; additional physical PDF page 99; printed 6-1 and 7-1, physical PDF page 85. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  77. You are driving the tractor without a trailer. Should its lighter weight make you assume it will stop more quickly?

    Correct answer: No; a bobtail tractor can have poor braking traction and need extra stopping room.

    The manual warns that bobtail tractors can be difficult to stop smoothly. Reduced load on the drive wheels can reduce available traction.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 6.1.3 Brake Early; printed 6-1, physical PDF page 85. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  78. In your mirror, the trailer begins swinging sideways because its wheels have locked during braking. What helps restore its path?

    Correct answer: Release the braking that locked the trailer wheels so they can regain traction.

    A trailer-wheel braking skid requires the wheels to roll again to regain traction. Extra trailer braking worsens the skid.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 6.1.5 Prevent Trailer Skids; continued on physical PDF page 87; printed 6-2–6-3, physical PDF page 86. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  79. A driver proposes using the trailer hand valve to hold a parked rig while leaving the cab. Why is that unsafe?

    Correct answer: Air can leak away and release those brakes; use the proper parking controls and secure the vehicle.

    The hand valve is for testing trailer brakes, not unattended parking or ordinary driving. Air-operated service brakes may release as pressure leaks away.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 6.2.1 Trailer Hand Valve; printed 6-4, physical PDF page 88. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  80. A trailer air line tears apart after a breakaway. Which protection is intended to keep the leak from draining all air out of the tractor?

    Correct answer: The tractor protection valve closing the air supply to the trailer.

    The tractor protection valve helps preserve air in the tractor if the trailer separates or develops a major leak.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 6.2.2 Tractor Protection Valve; printed 6-5, physical PDF page 89. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  81. One trailer air line supplies the trailer reservoirs and controls emergency braking if its pressure is lost. Which line performs these functions?

    Correct answer: The emergency or supply line.

    The supply line charges trailer tanks and controls emergency braking. The service line carries the braking command associated with the pedal or hand control.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 6.2.4 Trailer Air-lines; printed 6-5, physical PDF page 89. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  82. After coupling a spring-braked trailer, you discover that its service and supply air lines were crossed. What problem can this cause?

    Correct answer: The trailer reservoirs may not charge, so the spring brakes may not release.

    Crossed lines may send supply air into the service line instead of charging the reservoirs and releasing spring brakes. Verify correct connections and test trailer braking before driving.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 6.2.5 Hose Couplers (Glad Hands), crossed air-lines continuation; printed 6-6, physical PDF page 90. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  83. Before backing the tractor under a semitrailer, how should its front height relate to the fifth wheel?

    Correct answer: Low enough that the tractor raises the trailer slightly as it backs under.

    Correct height supports proper engagement. A trailer set too high can miss the locking mechanism; one set too low can be damaged.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 6.4.1 Coupling Tractor-Semitrailers, Step 6 Check Trailer Height; printed 6-8, physical PDF page 92. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  84. A gentle coupling pull-test seems satisfactory. During the visual check, the jaws appear around the kingpin head instead of its shank. May you depart?

    Correct answer: No; the coupling is not correct and must be fixed before travel.

    Verify that the jaws close around the kingpin shank, the fifth-wheel plates meet, and the locks are secured. A tug alone does not replace the visual check.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 6.4.1 Coupling Tractor-Semitrailers, Step 13 Inspect Coupling; continued on physical PDF page 93; printed 6-8–6-9, physical PDF page 92. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  85. A coupled trailer’s landing feet are a few inches above the ground. What remains necessary before departure?

    Correct answer: Raise the landing gear fully and secure its crank handle.

    Partly raised landing gear can catch on tracks or other obstructions. Fully raise it, secure the handle, and check tractor-to-trailer clearance.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 6.4.1 Coupling Tractor-Semitrailers, Step 15 Raise Front Trailer Supports (Landing Gear); printed 6-9, physical PDF page 93. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  86. While uncoupling, why do you pause with the tractor frame still beneath the trailer after the fifth wheel has cleared?

    Correct answer: To check that the landing gear and ground support the trailer, with the frame still available as protection if it drops.

    The partial pull-out lets you confirm support before fully clearing the trailer. Firm ground, straight alignment, and correct landing-gear placement are essential.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 6.4.2 Uncoupling Tractor-Semitrailers, Steps 7–9; continued on physical PDF page 94; printed 6-9–6-10, physical PDF page 93. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  87. You are assembling a set of two trailers with substantially different loaded weights. Which order does the manual recommend for the safest handling?

    Correct answer: The more heavily loaded trailer first, immediately behind the tractor.

    For the safest handling, place the heavier semitrailer ahead of the lighter one. Multiple-trailer combinations require attention to how the load is distributed between units.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 7.2.1 Coupling Twin Trailers, loaded-trailer order; printed 7-1, physical PDF page 99. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  88. You are choosing a rest-area parking space for a set of doubles. Which feature deserves special consideration?

    Correct answer: A route that lets the entire rig pull straight through when leaving.

    Avoid a parking position that traps a set of doubles in a difficult escape. Plan the exit before entering the space.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 7.1.7 Parking the Vehicle; printed 7-1, physical PDF page 99. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  89. A set of doubles is ready for travel. How should the service and supply shut-off valves at the rear of each trailer be positioned?

    Correct answer: Open at the first trailer and closed at the rearmost trailer.

    Air must flow through intermediate connections to the rear unit, while the final exposed outlets must be closed. Check dolly valves as applicable too.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 7.3.1 Additional Checks, Double and Triple Trailers, shut-off valves; printed 7-3, physical PDF page 101. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  90. During a properly secured air-continuity check, no air escapes when you briefly open the final trailer’s service-line valve with the service control applied. What should you do?

    Correct answer: Find and correct the lack of air flow through the trailers and dollies before travel.

    The check establishes that air reaches the rear of the complete combination. A closed intermediate valve or other problem can leave rear brakes without the required control pressure.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 7.4.1 Additional Air Brake Checks, Check That Air Flows to All Trailers; printed 7-4, physical PDF page 102. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  91. The converter dolly’s eye is resting in the front trailer’s pintle hook. What additional connection checks are still necessary?

    Correct answer: Check that the hook is latched and the safety chains are secured.

    A seated eye is not the complete connection check. Inspect the latch, chains, air connections, and electrical connections before operation.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 7.3.1 Additional Checks, converter-dolly connections; printed 7-4, physical PDF page 102. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  92. A helper reaches for the pintle-hook latch while the dolly is still supporting the rear trailer. What is the concern?

    Correct answer: The dolly tow bar can fly upward; remove the dolly from beneath the rear trailer before unhitching it.

    The manual warns not to unlock the pintle with the dolly still under the rear trailer. Follow the safe uncoupling order and secure every unit.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 7.2.2 Uncoupling Twin Trailers, Uncouple Rear Trailer and Uncouple Converter Dolly; continued on physical PDF page 101; printed 7-2–7-3, physical PDF page 100. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  93. A tank shell looks intact, but liquid is seeping around a discharge-valve connection. Is the vehicle ready to haul the load?

    Correct answer: No; valve, pipe, hose, and connection leaks are part of the tank inspection too.

    Tank inspection includes the shell, valves, pipes, hoses, covers, and vents. Do not transport a load in a leaking tank system.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 8.1.1 Leaks; printed 8-1 (printed header displays 8-8-1), physical PDF page 103. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  94. A partially filled liquid tanker has just stopped on ice. Why can the vehicle still be pushed forward?

    Correct answer: Liquid continuing to surge inside the tank can push against its end.

    Liquid in a partly filled tank can continue moving after the vehicle slows or stops. On a slick surface, that surge can move the vehicle.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 8.2.2 Danger of Surge; continued on physical PDF page 104; printed 8-1–8-2 (printed headers display 8-8-1 and 8-8-2), physical PDF page 103. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  95. Your tanker has separate compartments divided by solid bulkheads. What must you consider when deciding which compartments to fill or empty?

    Correct answer: How the resulting load distributes weight over the vehicle and its axles.

    Bulkheads divide the load into smaller tanks, but uneven filling or unloading can still overload the front or rear. Plan weight distribution throughout the operation.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 8.2.3 Bulkheads; printed 8-2 (printed header displays 8-8-2), physical PDF page 104. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  96. A driver says that tank baffles make abrupt lane changes safe because they control liquid movement. What is wrong with that reasoning?

    Correct answer: Baffles reduce forward-and-back surge, but sideways surge can still contribute to rollover.

    Openings in baffles allow flow between areas of the tank. They limit longitudinal surge, not all lateral movement or rollover risk.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 8.2.4 Baffled Tanks; printed 8-2 (printed header displays 8-8-2), physical PDF page 104. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  97. You change from a baffled tanker to a smooth-bore tanker. What handling change should you particularly anticipate?

    Correct answer: Stronger forward-and-back surge, requiring especially smooth starts and stops.

    A smooth-bore tank has no baffles to slow longitudinal liquid flow. Anticipate stops and make gradual control changes.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 8.2.5 Un-baffled Tanks and 8.3.1 Drive Smoothly; printed 8-2 (printed header displays 8-8-2), physical PDF page 104. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  98. A dispatcher asks you to fill every available gallon of a cargo tank with liquid. What must determine the actual loading amount?

    Correct answer: Required expansion space, the liquid’s weight, and applicable vehicle weight limits.

    Liquids can expand in transit, so loading must allow the appropriate outage. Dense liquids can also reach weight limits before filling the tank’s volume.

    Source: Iowa DOT official older Commercial Driver's License Manual, Hy-Brid Version October 2023 with July 2017 technical core; 8.2.6 Outage and 8.2.7 How Much to Load?; printed 8-2 (printed header displays 8-8-2), physical PDF page 104. Older technical guidance read 2026-10-01, not confirmation of the current media/326 edition, current Iowa qualification law, or current skills-test administration. ↗

  99. A passenger wants to leave a suitcase in the aisle beside an emergency exit because the ride is short. What should you require?

    Correct answer: Stow it securely without obstructing an aisle, doorway, or exit.

    Passenger baggage must not block access or become a moving hazard. A short journey does not make an obstructed escape path safe.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 4.2 Loading and Trip Start; printed 4-1–4-2, physical PDF page 71–72; reader lines 5463–5473. ↗

  100. Before carrying passengers, you find an emergency door that does not close securely. What is the appropriate conclusion?

    Correct answer: The defect must be addressed before operating the bus with passengers.

    The bus inspection includes properly operating doors, exits, and warning devices. Do not substitute an improvised restraint that defeats emergency access.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 4.1.2 Access Doors and Panels; 4.1.3 Bus Interior; printed 4-1, physical PDF page 71; reader lines 5432–5454. ↗

  101. A bus passes its exterior walk-around, but a passenger seat is loose and a handhold is damaged. Is the passenger-area inspection complete?

    Correct answer: No; passenger seats and handholds must also be safe and secure.

    Interior safety checks include seats, handholds, aisles, steps, and emergency equipment. Exterior condition alone is not enough to establish passenger safety.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 4.1.3 Bus Interior; printed 4-1, physical PDF page 71; reader lines 5437–5449. ↗

  102. A passenger has just boarded your transit bus and is still finding a secure position. When should you begin moving?

    Correct answer: After the passenger is seated or otherwise braced, then accelerate smoothly.

    Wait for boarding passengers to be seated or braced. Smooth acceleration helps prevent falls.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 4.3.2 At Stops; printed 4-3, physical PDF page 73; reader lines 5579–5585. ↗

  103. A disruptive adult passenger is making continued bus operation unsafe. Which response follows the manual’s safety guidance?

    Correct answer: Manage the problem at a safe location rather than putting the person off where it would be unsafe.

    Disruptive riders must not distract the driver into unsafe operation. The manual warns against discharging a rider where it would be unsafe.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 4.3.2 At Stops, disruptive riders; printed 4-3, physical PDF page 73; reader lines 5586–5592. ↗

  104. You signal to leave a bus stop, but nearby traffic has not made room. What is the safe assumption?

    Correct answer: The signal does not guarantee a gap; check traffic and move only when safe.

    The manual warns against assuming that signaling gives you the right of way when leaving a stop. Observe the traffic and use a safe opportunity to merge.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 4.3.3 Common Accidents; printed 4-3, physical PDF page 73; reader lines 5593–5605. ↗

  105. A disabled bus must be towed, and passengers can safely get off first. What is the manual’s guidance?

    Correct answer: Unload the passengers before towing.

    The manual advises against towing with passengers aboard unless unloading would be unsafe. In that exceptional situation, tow only to the nearest safe unloading place.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 4.5 Prohibited Practices, towing a disabled bus; printed 4-3, physical PDF page 73; reader lines 5658–5668. ↗

  106. Opening a transit bus door activates a brake-door interlock. Can that device replace the parking brake when securing the bus?

    Correct answer: No; use the proper parking brake rather than relying on the interlock.

    A brake-door interlock is not the parking brake. Follow the bus’s proper parking and securement procedure.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 4.6 Use of Brake-door Interlocks; printed 4-4, physical PDF page 74; reader lines 5671–5677. ↗

  107. A child is close to the front bumper below the driver’s direct view. Which school-bus mirrors are specifically intended to help check this danger zone?

    Correct answer: The correctly adjusted front crossover mirrors.

    Crossover mirrors show areas immediately in front of the bus and near the front wheels and service door. Use all mirrors in a systematic check; no single mirror covers every danger zone.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 10.1.5 Outside Left and Right Side Crossover Mirrors; printed 10-2, physical PDF page 128; reader lines 10044–10069. ↗

  108. You counted a child at the stop, but cannot account for that child after the others board. What should happen before the bus moves?

    Correct answer: Secure the bus, take the key, and check around and underneath it.

    The driver must account for children before departure. If a child outside cannot be located, secure the vehicle and inspect the surrounding danger zones.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 10.2.2 Loading Procedures; printed 10-4, physical PDF page 130; reader lines 10153–10175. ↗

  109. What should students be taught to do if they drop an item beside the bus during unloading?

    Correct answer: Leave it, move to a safe place, and get the driver’s attention.

    A child reaching for a dropped item may disappear from the driver’s view. The safe instruction is to leave it and notify the driver from outside the danger zone.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 10.2.5 Special Dangers of Loading and Unloading, Dropped or Forgotten Objects; printed 10-5, physical PDF page 131; reader lines 10305–10318. ↗

  110. The final school-bus stop is complete and the bus sounds empty. What check should still be made at the end of the route?

    Correct answer: Walk through and around the bus, checking especially for sleeping students and other problems.

    A physical post-trip inspection can find sleeping students, belongings, damage, and equipment problems that a quick mirror glance misses.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 10.2.6 Post-trip Inspection; printed 10-6, physical PDF page 132; reader lines 10327–10342. ↗

  111. After stopping a school bus at a railroad crossing, how can you improve the check for an approaching train?

    Correct answer: Silence passengers and noisy equipment, open the service door and driver’s window, and look and listen.

    The manual recommends reducing noise and opening the service door and driver's window to look and listen. Follow applicable state and local school-bus procedures as well; inactive warning lights do not prove the tracks are clear.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 10.4.3 Recommended Procedures, At the Crossing; printed 10-9, physical PDF page 135; reader lines 10551–10561. ↗

  112. A school bus stalls on the tracks and a train is approaching. What direction should evacuated students move?

    Correct answer: Away from the tracks and toward the approaching train, at an angle away from the bus.

    Get everyone out and clear immediately. Moving away from the tracks toward the approaching train helps avoid the likely path of debris if the train hits the bus.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 10.4.4 Special Situations, Bus Stalls or Trapped on Tracks; printed 10-9, physical PDF page 135; reader lines 10574–10579. ↗

  113. While children are unloading, two students inside begin arguing. What should remain your immediate focus?

    Correct answer: The children outside and the unloading danger zones; address the behavior once they are safe.

    Loading and unloading require the driver’s full outside attention. If needed, stop and secure the bus at a safe place to deal with a behavior problem after the unloading students are safe.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 10.5.1 Don't Deal with On-bus Problems When Loading and Unloading; 10.5.2 Handling Serious Problems; printed 10-9, physical PDF page 135; reader lines 10608–10628. ↗

  114. At an approved drop-off maneuver, backing is unavoidable and no safer option exists. Should students get off before or after the bus backs?

    Correct answer: After backing, so students are not outside the bus during the maneuver.

    Avoid backing wherever possible. If it is unavoidable, follow the lookout and inspection procedures and never back while students are outside; at a drop-off, back before unloading.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 10.7.3 Backing; printed 10-11, physical PDF page 137; reader lines 10751–10777. ↗

  115. A school bus is parked close to a roadside object. As the driver steers away, why must the rear overhang be watched in the mirrors?

    Correct answer: The tail can swing toward nearby objects on the side opposite the turn.

    A bus’s rear overhang can swing outward as it turns. Check mirrors before and during the turn to protect the clearance beside the rear of the bus.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 10.7.4 Tail Swing; printed 10-11, physical PDF page 137; reader lines 10778–10781. ↗

  116. Strong gusts are pushing a school bus sideways. What is the manual’s recommended response?

    Correct answer: Hold the wheel firmly, reduce speed, and stop safely off the roadway if necessary while coordinating with dispatch.

    The broad side of a bus can catch strong winds. Anticipate gusts, slow down, and wait safely if conditions cannot be managed.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 10.7.2 Driving in High Winds; printed 10-11, physical PDF page 137; reader lines 10738–10750. ↗

  117. A shipment is subject to hazardous-materials shipping-paper requirements, but the shipper says the paperwork will be emailed after you leave. What should you do?

    Correct answer: Do not accept it for transportation until the required, properly prepared shipping paper is available.

    This shipment requires shipping papers. Labels or a promise of later paperwork do not replace the properly prepared hazard information needed before accepting it for transportation.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.6.10 Where to Keep Shipping Papers and Emergency Response Information; printed 9-15, physical PDF page 119; reader lines 9361–9378. Retained federal corroboration, read September 29, 2026 (not re-fetched for this Iowa asset): 49 CFR 177.817(a), (d), https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-177/subpart-A/section-177.817. ↗

  118. You leave the controls of a truck carrying a hazardous-materials shipment that requires shipping papers. Where should those papers remain?

    Correct answer: In the driver-side door holder or on the driver’s seat, readily identifiable.

    Responders must be able to find the papers promptly. At the controls, keep them within reach while belted and visible or in the driver-door holder; away from the controls, use that holder or the driver’s seat.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.6.10 Where to Keep Shipping Papers and Emergency Response Information; printed 9-15, physical PDF page 119; reader lines 9361–9378. Retained federal corroboration, read September 29, 2026 (not re-fetched for this Iowa asset): 49 CFR 177.817(e), https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-177/subpart-A/section-177.817. ↗

  119. The correct hazard placard is attached, but a loose tarp covers its lower half. What needs to happen before travel?

    Correct answer: Secure the tarp and restore the placard’s required visibility and legibility.

    A placard must remain clear of obstructions such as tarps and be maintained so its message is legible. Merely having the right placard somewhere on the vehicle is insufficient.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.3.10 Placarding, continued; printed 9-8–9-9, physical PDF page 113 (also page 112); reader lines 8731–8748. Retained federal corroboration, read September 29, 2026 (not re-fetched for this Iowa asset): 49 CFR 172.516(c)(2), (6), https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-172/subpart-F/section-172.516. ↗

  120. Hazardous-material drums cannot slide out of the trailer, but they can strike one another and damage their fittings. Is that adequate securement?

    Correct answer: No; secure them against shifting, including movement between the packages.

    Secure packages against movement during normal transportation and protect valves or fittings from damage. Relative movement between packages can create leaks even inside a closed trailer.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.4.1 General Loading Requirements, Secure Against Movement; printed 9-10, physical PDF page 114; reader lines 8897–8899, 8908–8924. Retained federal corroboration, read September 29, 2026 (not re-fetched for this Iowa asset): 49 CFR 177.834(a), https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-177/subpart-B/section-177.834. ↗

  121. A hazardous-material package bears required orientation arrows. A loader wants to lay it on its side to fit another pallet. What is the correct response?

    Correct answer: Keep the package in the orientation indicated by the markings throughout transport.

    Required orientation markings describe how the package must be positioned, not merely how it should look at delivery.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.3.7 Package Markings and Labels; printed 9-8, physical PDF page 112; reader lines 8665–8693. Retained federal corroboration, read September 29, 2026 (not re-fetched for this Iowa asset): 49 CFR 177.834(b), https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-177/subpart-B/section-177.834. ↗

  122. Before workers begin loading hazardous material into a motor vehicle, what must the driver ensure about the vehicle itself?

    Correct answer: Set the parking brake securely and take other reasonable precautions against movement.

    Vehicle movement during a transfer can damage containers or connections. The securement requirement applies before loading or unloading begins.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.4.1 General Loading Requirements; printed 9-10, physical PDF page 114; reader lines 8897–8899. Retained federal corroboration, read September 29, 2026 (not re-fetched for this Iowa asset): 49 CFR 177.834(e), https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-177/subpart-B/section-177.834. ↗

  123. Class 3 flammable liquid is being unloaded and a person approaches the transfer area with a lighted cigarette. What is the necessary safety response?

    Correct answer: Keep the ignition source away and prevent smoking near the loading or unloading operation.

    Smoking and flames create an ignition hazard during flammable-liquid loading and unloading. Keep those ignition sources away from the operation.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.4.1 General Loading Requirements, No Smoking; printed 9-10, physical PDF page 114; reader lines 8911–8918. Retained federal corroboration, read September 29, 2026 (not re-fetched for this Iowa asset): 49 CFR 177.834(c), (d), https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-177/subpart-B/section-177.834. ↗

  124. You stop to fuel the power unit of a truck carrying placarded hazardous material. Which arrangement is correct?

    Correct answer: Shut off the engine and have a person control fueling at the fill point.

    For the covered vehicle, the engine must not operate during fueling, and a person must control the process at the point where the fuel tank is filled.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.6.7 Refuel with Engine Off; printed 9-14, physical PDF page 118; reader lines 9337–9340. Retained federal corroboration, read September 29, 2026 (not re-fetched for this Iowa asset): 49 CFR 397.15, https://www.ecfr.gov/current/title-49/subtitle-B/chapter-III/subchapter-B/part-397/subpart-A/section-397.15. ↗

  125. A placarded load can use a practical, permitted route around a crowded downtown area. What does the manual's safety guidance advise if going downtown would only be more convenient?

    Correct answer: Use the route around the crowded area despite the inconvenience.

    The manual advises avoiding heavily populated areas when another route is available and checking applicable permits and route restrictions before starting.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.6.5 Route Restrictions; printed 9-14, physical PDF page 118; reader lines 9291–9311. ↗

  126. At pickup, you notice liquid escaping from a hazardous-material package. The shipper offers to place it on an absorbent pad. What is the proper decision?

    Correct answer: Refuse the leaking shipment and have the problem handled safely before transport.

    The driver’s responsibilities include refusing leaking packages and improper shipments. A pad or a waiver does not repair containment.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.2.3 The Driver; printed 9-2, physical PDF page 106; reader lines 8105–8112. ↗

  127. Emergency responders need to identify a load’s hazards quickly. Which shipping-paper information is especially useful for finding the relevant Emergency Response Guidebook entry?

    Correct answer: The proper shipping name and hazardous-material identification number.

    The ERG is indexed using material identification information, including proper shipping names and identification numbers. Accurate papers help responders identify the material.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.7.1 Emergency Response Guidebook; printed 9-15, physical PDF page 119; reader lines 9414–9425. ↗

  128. An unknown substance appears to be leaking from hazardous-material cargo. Should you approach and smell it to identify the chemical?

    Correct answer: No; use shipment information from a safe position and avoid contact or inhalation.

    Do not identify a leak by touching or smelling it. Toxic material can injure you, and smell is not a reliable warning of danger.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.7.3 Fires, cargo leaks; printed 9-16, physical PDF page 120; reader lines 9464–9472. ↗

  129. You suspect a hazardous-material cargo fire and the closed trailer doors are hot. What is the appropriate action?

    Correct answer: Keep the doors closed, call for emergency help, and warn people away.

    Opening doors can feed the fire with oxygen. Hazardous-material fires require specialized training and equipment; keep shipment information available for responders.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.7.3 Fires; printed 9-16, physical PDF page 120; reader lines 9445–9463. ↗

  130. Hazardous material is leaking from your stopped vehicle. A truck stop with a telephone is several miles away. Should you continue there to get help?

    Correct answer: No; move only as safety requires, keep people away, and summon help without spreading the leak along the road.

    The manual warns against continuing a leaking journey merely to find help. Protect yourself, keep others away and upwind, and give emergency responders the shipment information.

    Source: Iowa DOT-hosted CDL Manual, Hy-Brid October 2023; section text Version July 2017 (older source, not verified as current catalog edition). 9.7.2 Crashes/Incidents; 9.7.3 Fires, leaking cargo; printed 9-15–9-16, physical PDF page 120 (also page 119); reader lines 9426–9441, 9473–9515. ↗

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