Mississippi CDL — General Knowledge practice
Mississippi 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
14 questions · pass with 11 correct. You get instant feedback and an explanation after every answer.
Study questions with answers
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.
Show all 12 questions with answers
1. When a road crosses more than one set of tracks, how is this shown at the crossbuck?
Correct answer: A sign under the crossbuck gives the number of tracks
A small sign beneath the crossbuck states how many tracks the road crosses. That matters because a train on one track can hide another.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Warning Signs and Devices)
2. Near a railroad crossing on a two-lane road, which sign may be posted along with the RR pavement markings?
Correct answer: A no-passing zone sign
Two-lane approaches to a crossing may carry a no-passing pavement marking and a no-passing zone sign. Don't pass as you near the tracks.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Warning Signs and Devices)
3. What does the round, black-on-yellow sign placed before a public railroad crossing tell you to do?
Correct answer: Slow down, look and listen for a train, and be ready to stop
This is the advance warning sign. It means reduce speed, check for trains, and get ready to stop short of the tracks. Vehicles carrying passengers or hazmat must stop.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Warning Signs and Devices)
4. On a cargo tank's placard or orange panel, what is the four-digit number used for?
Correct answer: It tells first responders which hazardous material is inside
Identification numbers are four-digit codes, preceded by 'UN' or 'NA', that responders look up in the US DOT Emergency Response Guidebook.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Hazardous Materials Rules for All Commercial Drivers)
5. How must a hazardous materials placard be shaped and sized?
Correct answer: A diamond at least 9.8 inches square, set on one point
Placards are diamonds — squares turned on a point — at least 9.8 inches (250 mm) square, and must be readable from all four directions.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Hazardous Materials Rules for All Commercial Drivers)
6. An overpass has a posted clearance height. Why shouldn't you assume the posted figure is correct?
Correct answer: Repaving or packed snow may have reduced the clearance since it was posted
Road work and snow can lower the real clearance below the posted number. If you doubt you can fit, go slowly — or take another route.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Space Overhead)
7. A placard shows hazard class 3. What type of material does that class cover?
Correct answer: Flammable liquids such as gasoline
In the hazard class table, class 3 is flammable materials like gasoline and acetone. Explosives are class 1, radioactive materials class 7, and corrosives class 8.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Hazardous Materials Rules for All Commercial Drivers)
8. A vehicle that requires hazardous materials placards must display at least how many identical placards?
Correct answer: Four: front, rear, and each side
Placards go on all four sides so the hazard class can be read from any direction.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Hazardous Materials Rules for All Commercial Drivers)
9. An off-ramp has a posted speed sign. Why might that speed still be too fast for your truck?
Correct answer: The posted speed may suit cars but not large or heavily loaded vehicles
Ramp speeds are often set with cars in mind. Ramps that drop downhill while curving are especially risky, so be slow enough before reaching the curve.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Hazardous Roads)
10. Some public railroad crossings are posted with signs about train horns. What do those signs indicate?
Correct answer: That trains do not sound their horns at that crossing
At some crossings trains may not, or are not allowed to, sound horns, and those crossings should be signed. Don't count on hearing a train anywhere — cab noise can mask a horn.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Driving Procedures)
11. On the CDL road test, just after you drive under an overpass, what might the examiner ask you?
Correct answer: What clearance height was posted
Examiners may ask about the posted clearance after an overpass, the posted weight limit after a bridge, or any other traffic sign on the route.
Source: Mississippi CDL Manual — Section 13: On-road Driving (Bridge/Overpass/Sign)
12. A red triangle with an orange center on the back of a vehicle identifies it as:
Correct answer: A slow-moving vehicle
Mopeds, farm machinery, construction equipment, and tractors may carry this slow-moving vehicle emblem. Spotting it early helps you avoid closing on them too fast.
Source: Mississippi CDL Manual — Section 2: Driving Safely (Drivers Who Are Hazards)
More CDL — General Knowledge topics
Practice Road Signs in another state
Every Mississippi question is written from the official Mississippi 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