NJ commercial cdl study set

New Jersey Mountain Driving and Emergencies Practice Questions

30 New Jersey commercial cdl questions on mountain driving and emergencies, each with the correct answer and an explanation from the MVC handbook.

Mountain Driving and Emergencies questions

  1. 1. What is the most important factor in choosing a safe speed for a long downgrade?

    1. A. The total weight of the vehicle and cargo
    2. B. The age of the brake linings fitted
    3. C. The number of axles on the trailer

    Answer: A — The total weight of the vehicle and cargo

    Weight determines how much braking energy must be dissipated on the descent.

  2. 2. How should the service brakes be used on a long steep downgrade?

    1. A. Held down steadily the whole way down
    2. B. Pumped rapidly and continuously
    3. C. In firm applications, then released

    Answer: C — In firm applications, then released

    Snub braking lets the drums cool between applications and prevents brake fade.

  3. 3. When should a driver select a lower gear for a downgrade?

    1. A. Only if the brakes begin to fade
    2. B. Before starting down the hill
    3. C. Halfway down as speed builds

    Answer: B — Before starting down the hill

    Modern transmissions may not allow a downshift once speed has built, so the gear must be chosen at the top.

  4. 4. What causes brake fade?

    1. A. Excessive heat from long braking
    2. B. Water on the brake drums
    3. C. Low air pressure alone

    Answer: A — Excessive heat from long braking

    Heat expands the drums and reduces friction, so the same pedal pressure produces less braking.

  5. 5. What is an escape ramp for?

    1. A. To let slow vehicles rejoin traffic
    2. B. To weigh trucks before a long grade
    3. C. To stop a runaway vehicle on a downgrade

    Answer: C — To stop a runaway vehicle on a downgrade

    Escape ramps use gravity or soft material to stop a vehicle that can no longer brake.

  6. 6. What causes most commercial vehicle skids?

    1. A. Improper mirror adjustment
    2. B. Driving too fast for conditions
    3. C. Worn windscreen wipers

    Answer: B — Driving too fast for conditions

    Excessive speed for the conditions is behind the great majority of skids.

  7. 7. How should a driver correct a drive-wheel skid?

    1. A. Stop braking and steer where you want to go
    2. B. Brake harder to regain grip
    3. C. Hold the steering straight and wait

    Answer: A — Stop braking and steer where you want to go

    Removing the input that caused the skid comes first, then countersteering realigns the vehicle.

  8. 8. What is a jackknife?

    1. A. The tractor's front wheels losing grip
    2. B. The trailer brakes locking only
    3. C. The trailer swinging out of line

    Answer: C — The trailer swinging out of line

    A trailer that loses traction can swing around, folding the combination like a pocket knife.

  9. 9. What are the signs of a tyre failure while driving?

    1. A. The temperature gauge rising
    2. B. A bang, vibration, or heavy steering
    3. C. A gradual loss of engine power

    Answer: B — A bang, vibration, or heavy steering

    Sound, vibration, and steering feel are the three cues that a tyre has failed.

  10. 10. What should a driver do immediately after a front tyre blows out?

    1. A. Hold firmly and stay off the brakes
    2. B. Brake hard at once
    3. C. Steer sharply toward the shoulder

    Answer: A — Hold firmly and stay off the brakes

    Braking hard with a failed front tyre can pull the vehicle out of the lane.

  11. 11. What should you do before opening the bonnet of a vehicle that may be on fire?

    1. A. Open it fully so that the heat escapes
    2. B. Open it and pour water on the engine
    3. C. Avoid opening it, because air feeds the fire

    Answer: C — Avoid opening it, because air feeds the fire

    Opening the engine compartment supplies oxygen and can turn a contained fire into a flare-up.

  12. 12. How should a fire extinguisher be aimed?

    1. A. Directly into the smoke
    2. B. At the base of the fire
    3. C. At the top of the flames

    Answer: B — At the base of the fire

    The fuel is at the base, so that is where the extinguishing agent must reach.

  13. 13. How should a driver adjust speed on packed snow?

    1. A. Reduce speed by about half
    2. B. Maintain the posted limit
    3. C. Reduce by about a quarter

    Answer: A — Reduce speed by about half

    Packed snow roughly halves available traction, so speed should be cut accordingly.

  14. 14. What should a driver check more often in very hot weather?

    1. A. Only the fuel level
    2. B. Only the mirrors
    3. C. Tyre pressure and coolant

    Answer: C — Tyre pressure and coolant

    Heat raises tyre pressure and stresses the cooling system, both of which need monitoring.

  15. 15. How should a commercial driver adjust for fog?

    1. A. Maintain speed and follow the vehicle ahead closely
    2. B. Slow down and use low beams
    3. C. Use high beams for more light

    Answer: B — Slow down and use low beams

    High beams reflect off fog, and following closely to keep sight of tail lights removes all stopping room.

  16. 16. What determines the safe speed for a particular downgrade?

    1. A. Weight, length, steepness, and conditions
    2. B. Only the posted advisory speed on the sign
    3. C. Only the age of the brake linings

    Answer: A — Weight, length, steepness, and conditions

    All of these factors together set how much heat the brakes will have to absorb.

  17. 17. What is the effect of using an engine or exhaust brake on a downgrade?

    1. A. It replaces the parking brake
    2. B. It increases stopping distance
    3. C. It helps control speed on the grade

    Answer: C — It helps control speed on the grade

    Auxiliary braking keeps the service brakes cool and available for when they are actually needed.

  18. 18. What are the warning signs that brakes are fading?

    1. A. The vehicle pulls to one side
    2. B. The pedal travels further than usual
    3. C. The pedal becomes harder

    Answer: B — The pedal travels further than usual

    Increasing pedal travel with decreasing effect is the classic fade symptom on a long descent.

  19. 19. What should a driver do if the brakes fade badly on a downgrade?

    1. A. Use an escape ramp if there is one
    2. B. Pump the brakes harder
    3. C. Shift to neutral to coast

    Answer: A — Use an escape ramp if there is one

    An escape ramp exists precisely for the situation where speed can no longer be controlled.

  20. 20. What causes a front-wheel skid?

    1. A. Braking very gently on a dry road
    2. B. Steering with both hands
    3. C. Driving too fast for conditions

    Answer: C — Driving too fast for conditions

    When the front tyres lose grip the vehicle continues straight regardless of steering input.

  21. 21. How should a driver recover from a front-wheel skid?

    1. A. Accelerate to transfer weight rearward
    2. B. Stop steering and braking to regain grip
    3. C. Steer harder in the intended direction

    Answer: B — Stop steering and braking to regain grip

    Adding more steering to a sliding front tyre does nothing until grip returns.

  22. 22. How can a driver reduce jackknife risk on a slippery road?

    1. A. Slow early and brake gently
    2. B. Brake with the trailer hand valve
    3. C. Accelerate through slippery patches

    Answer: A — Slow early and brake gently

    Smooth, early inputs keep the trailer tracking behind the tractor.

  23. 23. How can a driver reduce the chance of a tyre failure?

    1. A. Drive slowly at all times
    2. B. Replace tyres annually regardless of wear
    3. C. Check pressure and condition each trip

    Answer: C — Check pressure and condition each trip

    Under-inflation and overloading generate the heat that destroys a tyre at speed.

  24. 24. What should a driver do after safely stopping following a blowout?

    1. A. Continue on the remaining tyres
    2. B. Place warning devices, then inspect
    3. C. Drive slowly to the next exit

    Answer: B — Place warning devices, then inspect

    A failed tyre may have damaged adjacent components, and the stopped vehicle is a hazard.

  25. 25. What is a common cause of vehicle fires in commercial vehicles?

    1. A. Under-inflated tyres and touching duals
    2. B. Overfilled coolant and clean tyres
    3. C. New brake linings bedding in

    Answer: A — Under-inflated tyres and touching duals

    Tyre friction and electrical shorts are among the most frequent ignition sources.

  26. 26. Where should a driver stop a vehicle that is on fire?

    1. A. At the nearest fuel station
    2. B. In a tunnel for containment
    3. C. In an open area away from buildings

    Answer: C — In an open area away from buildings

    An open area limits what the fire can spread to and gives responders room to work.

  27. 27. What should a driver check about the exhaust system before winter driving?

    1. A. That the silencer is newly fitted
    2. B. That there are no leaks into the cab
    3. C. That the pipe is painted and clean

    Answer: B — That there are no leaks into the cab

    A sealed cab in cold weather makes an exhaust leak far more dangerous.

  28. 28. How does a driver check for ice on the road while driving?

    1. A. Watch for ice on mirrors and aerials
    2. B. Test the brakes at speed
    3. C. Watch the temperature gauge only

    Answer: A — Watch for ice on mirrors and aerials

    Ice accumulating on exposed vehicle parts signals that the road surface is at or below freezing.

  29. 29. What is the risk of a tyre running under-inflated in hot weather?

    1. A. The tread wears more evenly
    2. B. Fuel economy improves
    3. C. Heat builds until the tyre fails

    Answer: C — Heat builds until the tyre fails

    Flexing sidewalls generate heat, and high ambient temperature brings the tyre closer to failure.

  30. 30. How should a driver adjust speed at night?

    1. A. Increase speed since traffic is lighter
    2. B. Slow enough to stop within the beam
    3. C. Maintain the daytime speed

    Answer: B — Slow enough to stop within the beam

    Overdriving the headlights leaves no room to react to what appears at their edge.

Questions about this study set

How many mountain driving and emergencies questions are on this page?

30, each with the correct answer and an explanation drawn from New Jersey's commercial cdl handbook.

Are these the real NJ DMV questions?

No. These are practice questions written from the MVC handbook. They cover the same rules the official test draws on, but the wording is ours.

Where can I take a full New Jersey practice test?

The New Jersey state page lists full-length timed tests for every licence type and applicant path.