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Quizzes > Lifestyle & Hobbies > Travel & Transportation

CDL General Knowledge II Quiz: Test What You Should Look for Ahead

What are the two main things to look for ahead? Test your perception distance and stopping skills now!

Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art illustration for CDL General Knowledge quiz on mastering driving skills on dark blue background

This CDL General Knowledge quiz helps you practice what to look for ahead so you spot hazards early, judge perception distance, and plan safe stops. Use it to check gaps before the exam, tune your following distance, and then try the full practice or the speed round .

What does perception distance represent in the stopping distance calculation?
The total distance to bring the vehicle to a stop
The distance from when brakes start to when they lock
The distance traveled while the driver recognizes a hazard
The distance of skid marks left after stopping
Perception distance is the distance your vehicle travels from the moment you see a hazard until you begin to apply the brakes. It is distinct from reaction distance and braking distance yet essential in calculating total stopping distance. Understanding perception distance helps drivers gauge how much space they need to identify danger before initiating a stop. Learn more at .
What is the recommended following distance under good driving conditions?
2 seconds
1 second
4 seconds
6 seconds
Under good road and weather conditions, a four-second following distance allows truck drivers adequate time to perceive hazards and react accordingly. This buffer helps reduce the likelihood of rear-end collisions, especially at higher speeds. Longer distances may be required in poor weather or heavy traffic. For details, see .
Approximately how many feet per second does a vehicle travel at 55 miles per hour?
60 feet per second
90 feet per second
70 feet per second
80 feet per second
To convert miles per hour to feet per second, multiply by 1.467. Thus, at 55 mph a vehicle travels about 55 × 1.467 ? 80.7 feet per second. This conversion helps drivers estimate stopping distances and safe following gaps. For more conversion examples, visit .
In the IPDE process, what does the 'P' stand for?
Prepare
Predict
Plan
Prevent
The IPDE process is a systematic approach: Identify hazards, Predict what will happen, Decide how to respond, and Execute the maneuver. 'Predict' involves anticipating potential developments based on current traffic and road conditions. Effective prediction allows drivers to prepare for hazards before they occur. More on this process can be found at .
How far ahead should you ideally scan the road under good driving conditions?
1 - 2 seconds ahead
12 - 15 seconds ahead
3 - 5 seconds ahead
4 - 6 seconds ahead
Scanning 12 - 15 seconds ahead (about a quarter mile at highway speeds) gives drivers time to identify hazards early. This distance helps in planning lane changes, speed adjustments, and safe stopping. Failing to scan far enough ahead increases the chance of sudden braking or swerving. For scanning techniques, see .
Approximately how many feet will a vehicle travel during a 1-second reaction time at 30 miles per hour?
30 feet
60 feet
22 feet
44 feet
At 30 mph, convert to feet per second: 30 × 1.467 ? 44 ft/s. During a 1-second reaction time, the vehicle travels that distance before braking begins. Knowing this helps in calculating total stopping distance. Check conversion tables at .
In foggy conditions, which headlights should you use?
Hazard lights
Parking lights only
High-beam headlights
Low-beam headlights
High beams reflect off fog and reduce visibility. Low beams help you see the road and other vehicles more clearly without glare. If visibility is extremely poor, consider pulling over safely until conditions improve. See for more on headlight use.
What is the best action to take before entering a sharp curve on a downgrade?
Accelerate into the curve to maintain momentum
Reduce speed while still on straight road
Brake hard during the curve
Shift to neutral before the curve
Slowing down before the curve reduces the risk of skidding and brake overheating on a downgrade. Entering too fast or braking inside the curve can lead to loss of control. Always choose an appropriate gear and speed in advance. Guidance is available at .
On wet pavement, stopping distance can be up to how many times longer than on dry pavement?
Half as long
The same length
Twice as long
Three times longer
Wet surfaces reduce tire traction significantly, doubling the distance needed to stop compared to dry roads. Drivers should adjust following distances accordingly in rain or standing water. Maintaining space helps prevent collisions. For more details, see .
On a long downhill grade, what is the recommended maximum time you should apply your brakes before releasing them to cool?
5 seconds
15 seconds
60 seconds
30 seconds
Continuous braking can overheat and fade brakes, so on long downgrades apply brakes for no more than 15 seconds, then release to let them cool. Use engine braking alongside this method. This technique prevents brake failure on steep declines. More guidelines are at .
When visibility is reduced by fog, what should you base your driving speed on?
The distance you can see ahead
The speed of the vehicle in front
The posted speed limit
The last speedometer reading
In fog, the safe driving speed depends on how far you can clearly see - your stopping distance must fit within your visible range. Relying on speed limits or other vehicles can be dangerous if visibility is poor. Always slow down to maintain control. Read more at .
What does an advisory speed plate below a curve warning sign indicate?
Maximum speed in all conditions
Minimum legal speed
Enforced speed limit by radar
Recommended safe speed under ideal conditions
An advisory speed plate suggests the maximum speed for safely negotiating the curve under ideal weather and traffic. It is not a legal limit but a recommendation. Adjust lower when conditions are poor. Further explanation is available at .
Before descending a steep hill, which vehicle system should be checked most carefully?
Windshield wipers
Air conditioning system
Brake system
Audio or entertainment system
Ensuring that the brake system is fully functional, properly adjusted, and free of leaks is vital before a long descent. Overheating brakes on steep grades can lead to brake fade or failure. Use engine braking to reduce wear. Read more at .
When passing another vehicle on a two-lane road, before returning to your lane you must see __________.
The entire front of the passed vehicle in your rearview mirror
Its headlights
Its license plate
Its rear bumper
You should see the full front of the vehicle you passed in your rearview mirror before pulling back into the lane. This ensures you have adequate space and that you aren't crowding the other driver. Always signal and check mirrors and blind spots. Guidelines are provided at .
In icy conditions, to maintain a safe following distance, you should use a __________.
3-second rule
Immediate stop distance
12-second rule
5-second rule
On ice, traction is severely reduced and stopping distances increase dramatically. Extending your following distance to at least 12 seconds gives you the extra space needed to react and stop safely. Shorter gaps can lead to collisions. See for winter driving tips.
What is brake fade?
Loss of braking power due to overheated brakes
A type of parking brake
Increased pedal pressure in wet conditions
The sound brakes make when cold
Brake fade occurs when the braking surfaces overheat, reducing friction and braking effectiveness. It often happens on long downgrades if brakes are used continuously without cooling. Using engine braking and proper brake application intervals helps prevent fade. More at .
How does a strong tailwind affect your stopping distance?
It decreases stopping distance
It improves engine braking
It has no effect
It increases stopping distance
A tailwind pushes you forward, increasing the distance needed to slow and stop the vehicle. This can be dangerous on approaches to hazards or stops. Drivers should compensate by reducing speed and increasing following distance. For wind effects, see .
Approximately how many feet will a truck travel during a 0.7-second brake lag time at 65 mph?
45 feet
67 feet
80 feet
100 feet
Brake lag time is the delay between pressing the brake pedal and when braking begins. At 65 mph (?96 ft/s), a 0.7-second lag covers about 67 feet (96×0.7). This distance must be added to total stopping distance. Learn more at .
When rain first begins to fall on a hot road, why is the pavement most slippery?
Oil and grease rise to the surface mixing with water
The road temperature drops below freezing
Potholes fill up with water
Water cools the asphalt rapidly
After a dry period, oil and grease on the road surface rise when the pavement heats. Initial rainfall mixes these contaminants with water, creating a very slick film. Drivers should slow significantly during the first few minutes of rain. More at .
Hydroplaning can begin at speeds as low as __________ on a wet road.
50 mph
35 mph
65 mph
20 mph
Hydroplaning occurs when tires lose contact with the pavement due to water buildup. It can start at speeds around 35 mph in just 1/10 inch of water. Slowing down and avoiding deep puddles reduces the risk. For hydroplaning guidance, see .
On packed snow, you should increase your following distance to at least __________.
6 seconds
4 seconds
3 seconds
2 seconds
Packed snow reduces tire traction, lengthening stopping distances dramatically. A six-second following distance provides extra time to react safely. Shorter gaps may lead to skids or collisions. Winter driving tips are at .
At night, within what distance of an oncoming vehicle must you dim your high beams?
200 feet
800 feet
500 feet
1000 feet
Most states require drivers to switch from high beams to low beams when within 500 feet of an oncoming vehicle. High beams can blind other drivers and reduce overall road safety. Check local regulations for exact requirements. See .
When driving a vehicle equipped with ABS, what is the proper braking technique?
Press and hold the brake pedal firmly
Release and reapply brakes
Lightly tap the brakes
Pump the brakes rapidly
ABS systems pump the brakes automatically during a lockup to prevent skids. Pressing and holding the pedal lets ABS modulate pressure effectively. Pumping or releasing breaks can reduce ABS effectiveness. More info at .
During a pre-trip inspection of air brakes, a 5-second full brake application should result in a maximum pressure drop of __________.
8 psi
10 psi
3 psi
5 psi
Air brake systems should hold pressure during a 5-second full application; a drop of more than 3 psi indicates a leak or malfunction. Regular checks help avoid brake failure or reduced braking capacity. Refer to FMCSA standards for detailed criteria at .
What is the approximate total stopping distance at 60 mph, including a 1-second reaction time, 0.7-second brake lag, and 240 feet of braking distance?
500 feet
303 feet
450 feet
390 feet
Total stopping distance sums reaction (1 sec at 60 mph ? 88 ft), brake lag (0.7 sec at 60 mph ? 62 ft), and actual braking distance (240 ft), totaling about 390 ft. Accurate calculations ensure safe following distances. See calculation methods at .
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Study Outcomes

  1. Understand the Two Main Things to Look for Ahead -

    Identify and describe the two primary elements - road conditions and potential hazards - that commercial drivers must monitor when scanning ahead.

  2. Apply Effective Forward Scanning Techniques -

    Demonstrate how and when looking ahead of your vehicle while driving you should scan to maintain optimal awareness and safety.

  3. Calculate Perception Distance -

    Use perception distance CDL methods to determine how far ahead you see and react to obstacles under various driving conditions.

  4. Analyze Stopping Distance Increases with Speed -

    Evaluate why if you go twice as fast stopping distance increases and how faster speeds dramatically extend braking requirements.

  5. Anticipate Potential Hazards -

    Predict and prepare for road hazards such as traffic slowdowns, emergency vehicles, and environmental changes before they occur.

  6. Evaluate Safe Following and Stopping Practices -

    Combine knowledge of perception and braking distances to maintain safe following intervals and stopping practices in all driving scenarios.

Cheat Sheet

  1. Identify Hazards and Traffic Flow -

    When answering "what are two main things to look for ahead," remember to scan for road hazards (like debris or animals) and monitor surrounding traffic patterns. Prioritize obstacles and driver behavior at least 12 - 15 seconds ahead to give yourself reaction time (source: FMCSA). Use the SIP mnemonic - Surface, Indicators, Path - to quickly recall key checks.

  2. Calculate Perception Distance -

    Perception distance CDL calculations rely on your reaction time, usually about 1 second (NHTSA data). Multiply your speed in mph by 1.47 to get feet per second, then by reaction time: at 55 mph, perception distance ≈ 80 ft. Practicing this formula helps you internalize how far you travel before you even hit the brakes, boosting your confidence on the road.

  3. Understand Speed's Impact on Stopping -

    Remember the rule "if you go twice as fast stopping distance increases" roughly fourfold (Virginia Tech Transportation Institute research). This includes braking and reaction distances, so doubling speed from 30 mph to 60 mph increases total stopping distance from about 90 ft to 360 ft. Visualize squares (30² vs. 60²) to cement "whenever you double your speed your vehicle has about" four times the stopping distance.

  4. Scan 12 - 15 Seconds Ahead -

    When looking ahead of your vehicle while driving you should maintain a 12 - 15 second visual lead (approx. 0.25 miles at highway speeds). This anticipatory scanning, endorsed by state DMV manuals, lets you spot brake lights, traffic signals, and openings in congested lanes. It turns reactive driving into proactive safety, giving you ample time to adjust speed and maneuver smoothly.

  5. Use Mirror and Signal Checks -

    Alongside forward scanning, toggle through your mirrors every 5 - 8 seconds to track overtaking vehicles (CAA guidelines). Combine mirror checks with timely turn signals to communicate intent and reduce surprise maneuvers. This habit ensures you're not just looking forward but also aware of threats from behind and the sides, reinforcing a complete defensive strategy.

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