North Carolina CDL — General Knowledge practice
North Carolina CDL — General Knowledge: Road Signs practice test
Learn the shapes, colors, and meanings of regulatory, warning, and guide signs — from stop and yield to construction and school-zone signs.
Content reviewed against official driver handbooks · August 12, 2026
13 questions · pass with 10 correct. You get instant feedback and an explanation after every answer.
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12 sample Road Signs questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.
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1. What does the round, black-on-yellow advance warning sign before a railroad crossing tell you to do?
Correct answer: Slow down, look and listen, and be ready to stop
This round yellow sign warns you ahead of the crossing to reduce speed, watch and listen for a train, and be ready to halt at the tracks if one approaches.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.15.2)
2. If a sign reads 'Maximum Safe Speed' on a downgrade, what must you do?
Correct answer: Never exceed the posted speed
Never exceed the speed shown on a posted 'Maximum Safe Speed' or speed-limit sign on a downgrade, and heed signs about the grade's length and steepness.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.6.6)
3. A four-digit identification number preceded by 'UN' or 'NA' on a placard or orange panel identifies what?
Correct answer: The specific hazardous material being carried
The four-digit identification number, preceded by NA or UN, identifies the hazardous material so first responders can look it up in the Emergency Response Guidebook.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.23.3)
4. What shape and minimum size must a hazardous-materials placard be?
Correct answer: A diamond shape at least 10 3/4 inches square
Each placard has to measure a minimum of 10 3/4 inches on a side, sit as a diamond balanced on one point, and stay legible from every direction.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.23.3)
5. What does the handbook expect of you regarding the speed limits posted in a roadway work zone?
Correct answer: Obey them from the approach onward and never let your speed drift upward
Posted work-zone limits bind you the whole way through, so keep glancing at the speedometer on long stretches of construction, and ease off further in bad weather or when a worker stands near the lane.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.6.7)
6. After going under an overpass during the road test, what might the examiner ask you?
Correct answer: What the posted clearance or height was
The examiner may ask what the posted clearance or height under the overpass was, so you should note traffic signs as you drive the route.
Source: North Carolina CDL Driver Handbook — Section 13: On-road Driving (13.1.9)
7. How many identical placards must a placarded hazardous-materials vehicle display?
Correct answer: Four
A placarded vehicle must show at least four identical placards, mounted on the front, the rear, and both sides.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.23.3)
8. Which hazard class covers corrosives such as battery acid?
Correct answer: Class 8
Hazard Class 8 covers corrosives, including hydrochloric acid and battery acid.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.23.3)
9. Which hazard class number is used for explosives?
Correct answer: Class 1
Hazard Class 1 is explosives, such as ammunition, dynamite, and fireworks.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.23.3)
10. Signs identify certain public crossings where approaching trains do not sound a horn. What does that tell you?
Correct answer: You cannot count on hearing a train, so look carefully for one
No horn will be sounded there, and racket inside the cab can bury a horn anyway, so your own search of the tracks has to do the work before you commit to crossing.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.15.3)
11. Why should you not simply take a posted bridge or overpass height at face value?
Correct answer: New paving or packed snow may leave less room than the sign claims
Resurfacing work or hard-packed snow can raise the road under the structure after the number went up, leaving less room than the sign claims; if you are unsure you will fit, creep through or choose another route.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.7.4)
12. Where a roadway crosses several sets of rails, what is shown on the small sign fixed below the crossbuck?
Correct answer: How many tracks you have to cross
A plate mounted under the crossbuck counts the sets of rails at that crossing, so you know how much track your rig has to clear before it is safely past.
Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.15.2)
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Every North Carolina question is written from the official North Carolina driver handbook and checked against its current edition. DMV Test Free is a free, independent study resource — not affiliated with any DMV or government agency. About DMV Test Free