Louisiana CDL — General Knowledge Practice Test
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Louisiana CDL — General Knowledge questions with answers
20 sample questions from the Louisiana CDL — General Knowledge question bank — each with the correct answer, a short explanation, and the section of the official handbook it comes from.
1. Which knowledge test must every CDL applicant take?
Correct answer: The general knowledge test
All CDL applicants must pass the general knowledge test.
Source: Louisiana CDL Manual, Section 1.1.1 (Knowledge Tests)
2. Compared with a loaded truck, how does an empty truck stop?
Correct answer: It needs a greater distance because it has less traction
An empty truck has less traction, so it actually needs a greater distance to stop than a fully loaded one.
Source: Louisiana CDL Manual, Section 2.6.1 (The Effect of Vehicle Weight on Stopping Distance)
3. Your hydraulic brake pedal goes to the floor. Which of these can help slow the vehicle?
Correct answer: Downshifting and using the parking brake
You can downshift, pump the pedal to build pressure, and use the parking brake to slow a vehicle that has lost hydraulic braking.
Source: Louisiana CDL Manual, Section 2.17.3 (Brake Failure)
4. You are in the right lane and a truck is trying to merge onto the highway from an on-ramp. What is the courteous and safe action?
Correct answer: Move over to let the truck merge
Courtesy says move over to give the merging truck room, since a big rig needs much more time to reach highway speed.
Source: Louisiana CDL Manual, Sharing the Road with Big Trucks
5. About how much alcohol can the liver process in one hour?
Correct answer: About one drink per hour
The liver can only clear roughly one drink's worth of alcohol per hour, so drinking faster than that builds up your BAC.
Source: Louisiana CDL Manual, Section 2.22.1 (Alcohol and Driving)
6. Because a motorcycle presents such a small profile, how may it appear to other drivers?
Correct answer: Farther away and slower than it really is
A motorcycle's narrow silhouette can make it look farther away and slower than it actually is, so take a second look.
Source: Louisiana CDL Manual, Sharing the Road with Motorcycles
7. A crossbuck sign at a railroad crossing requires a driver to do what?
Correct answer: Yield the right-of-way to an approaching train
The X-shaped crossbuck marks the crossing and means you must give the right-of-way to any approaching train.
Source: Louisiana CDL Manual, Section 2.15.2 (Warning Signs and Devices)
8. During the engine-compartment step of a pre-trip inspection, what must be done before you raise the hood or tilt the cab?
Correct answer: Confirm the parking brake is set or the wheels are chocked
Make sure the parking brakes are on and/or the wheels are chocked before you open or tilt the engine compartment.
Source: Louisiana CDL Manual, Section 2.1.5 (Seven-step Inspection Method)
9. Within how many feet of an oncoming vehicle must you dim your high-beam headlights at night?
Correct answer: 500 feet
You should switch from high to low beam within 500 feet of an approaching vehicle to avoid blinding that driver.
Source: Louisiana CDL Manual, Section 2.11.5 (Night Driving Procedures)
10. About how much steering wheel play begins to make a vehicle hard to steer?
Correct answer: More than about 10 degrees of play
More than about 10 degrees of play, roughly 2 inches at the outer edge of a 20-inch wheel, makes a vehicle hard to steer.
Source: Louisiana CDL Manual, Section 2.1.3 (Steering System Defects)
11. How many driver licenses is a commercial driver permitted to hold at one time?
Correct answer: Only one license
A commercial driver may hold only one license; breaking this rule can bring a fine and jail time.
Source: Louisiana CDL Manual, Section 1.4 (Other CDL Rules)
12. Which endorsement is required to drive a tank vehicle?
Correct answer: The N endorsement
The 'N' endorsement is required to operate a tank vehicle carrying liquid or gas in large quantities.
Source: Louisiana CDL Manual, Section 1.1 (CDL Endorsements)
13. On packed snow, how much should you reduce your speed?
Correct answer: By about half or more
On packed snow you should cut your speed by half or more to keep traction.
Source: Louisiana CDL Manual, Section 2.6.2 (Matching Speed to the Road Surface)
14. When you do not have enough room to stop for an obstacle, what is often the better choice?
Correct answer: Steer around the obstacle
You can usually steer around an obstacle faster than you can stop, so turning away may be the better option.
Source: Louisiana CDL Manual, Section 2.17.1 (Steering to Avoid a Crash)
15. Before you start across a road with a large, slow vehicle, what must you be sure of?
Correct answer: That you can clear the whole roadway before approaching traffic arrives
Make sure you can clear the entire road before approaching traffic reaches you, because big vehicles accelerate slowly.
Source: Louisiana CDL Manual, Section 2.7.7 (Space Needed to Cross or Enter Traffic)
16. What effect can other drugs have when combined with alcohol?
Correct answer: Alcohol can worsen the effects of other drugs considerably
Combining alcohol with other drugs can worsen their effects considerably, so the safest rule is never to mix any drug with driving.
Source: Louisiana CDL Manual, Section 2.22.2 (Other Drugs)
17. How much of a traffic lane is a motorcycle entitled to use?
Correct answer: The full width of the lane
A motorcycle is allowed the full width of a lane; do not try to share the lane with one.
Source: Louisiana CDL Manual, Sharing the Road with Motorcycles
18. A small sign mounted just below a crossbuck at a rail crossing tells you what?
Correct answer: The number of tracks at the crossing
When a crossing has more than one set of rails, a plate under the crossbuck states how many tracks there are.
Source: Louisiana CDL Manual, Section 2.15.2 (Warning Signs and Devices)
19. You are stopped just beyond a hill or curve that blocks the view of your vehicle. What should you do with the rear warning triangle?
Correct answer: Move it back so drivers are warned within 500 feet
Move the back triangle farther down the road, back beyond the hill or curve, so approaching drivers get warning within 500 feet.
Source: Louisiana CDL Manual, Section 2.5.2 (Communicating Your Presence)
20. In rain, fog, or at dawn and dusk, which lights should you switch on to be seen?
Correct answer: Your low-beam headlights
When it is hard to see, turn on your headlights using the low beams rather than only clearance or identification lights.
Source: Louisiana CDL Manual, Section 2.5.2 (Communicating Your Presence)