Colorado CDL — General Knowledge practice
Colorado 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.
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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, yellow sign with a black border and a black 'X' posted ahead of a public rail crossing tell an approaching driver to do?
Correct answer: Slow down, look and listen for a train, and be prepared to stop if one approaches
The advance warning sign at a grade crossing directs you to ease off the throttle, watch and listen for a train, and be ready to halt at the rails if one is coming.
Source: Colorado CDL Manual, Section 2.15.2 (Warning Signs and Devices)
2. A small sign mounted below a crossbuck showing a numeral such as '2' or '3' tells the driver what?
Correct answer: The number of separate tracks the crossing covers
When a crossing spans more than one set of rails, the sign beneath the crossbuck states how many tracks must be cleared.
Source: Colorado CDL Manual, Section 2.15.2 (Warning Signs and Devices)
3. A crossbuck sign marking a highway-rail grade crossing places what legal duty on the driver?
Correct answer: It requires you to give the right-of-way to an approaching train
The X-shaped crossbuck requires you to yield to any train using the tracks, since a train always has the right-of-way at a crossing.
Source: Colorado CDL Manual, Section 2.15.2 (Warning Signs and Devices)
4. On a two-lane road, what does a no-passing zone sign posted at a railroad crossing indicate?
Correct answer: That passing other vehicles is prohibited at the crossing
A no-passing marking and sign at a rail crossing on a two-lane road prohibit passing other vehicles in that area.
Source: Colorado CDL Manual, Section 2.15.2 (Warning Signs and Devices)
5. Painted on the roadway before many railroad crossings on two-lane roads, an 'X' with the letters 'RR' carries what meaning?
Correct answer: It carries the same warning as the advance railroad sign to slow and prepare to stop
These pavement markings deliver the same message as the round advance warning sign: reduce speed and be ready to stop for a train.
Source: Colorado CDL Manual, Section 2.15.2 (Warning Signs and Devices)
6. Among the required emergency warning devices a commercial vehicle must carry are reflective triangles. How many does the manual say to carry?
Correct answer: Three reflective triangles
The vehicle must have warning devices for a stopped vehicle: three reflective triangles, or at least six fusees, or three liquid-burning flares.
Source: Colorado CDL Manual, Section 2.1.3 (What to Look For)
7. A reflective red triangle with a bright orange center attached to the rear of a vehicle ahead is a signal that the vehicle is what?
Correct answer: Designed to move much slower than surrounding traffic
The slow-moving vehicle emblem warns other drivers that the vehicle travels well below normal traffic speed, so you should expect to close on it quickly.
Source: Colorado CDL Manual, Section 2.8.3 (Drivers Who Are Hazards)
8. Signs posted several miles from the top of a steep mountain downgrade often point out the location of what safety feature?
Correct answer: An escape ramp for runaway vehicles
Escape-ramp signs tell drivers where a runaway-vehicle ramp is located; the ramp uses a bed of loose, soft material to stop a truck safely.
Source: Colorado CDL Manual, Section 2.16.4 (Proper Braking Technique)
9. Under the hazard-class system used on placards, gasoline and acetone belong to which class?
Correct answer: Class 3, flammable liquids
Flammable liquids such as gasoline and acetone are grouped in Hazard Class 3.
Source: Colorado CDL Manual, Section 2.23.2 (Hazard Class Definitions)
10. A vehicle that is required to display hazardous-materials placards must carry how many, and where?
Correct answer: Four matching diamond signs on the front, rear, and both sides
Placarding rules require four identical diamond-shaped signs, mounted on the front, the rear, and both sides so the hazard is readable from every direction.
Source: Colorado CDL Manual, Section 2.23.3 (Lists of Regulated Products)
11. The warning lamp that tells a driver the antilock braking system has a fault is what color?
Correct answer: Yellow
Tractors, trucks, and buses show a yellow ABS malfunction lamp on the dash; on trailers the yellow lamp is on the left side.
Source: Colorado CDL Manual, Section 2.18.3 (How to Know If Your Vehicle Is Equipped with ABS)
12. Signs posted for 'move-over' laws direct approaching drivers to do what near a stopped emergency vehicle?
Correct answer: Slow and move over to a lane away from the emergency vehicle when safe
Move-over laws, marked by roadside signs, require drivers to slow down and, when it is safe, change into a lane not next to the stopped emergency vehicle or work area.
Source: Colorado CDL Manual, Section 2.8.2 (Hazardous Roads)
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