South Carolina CDL — General Knowledge: Road Signs Practice Test

Question 1

How many identical placards must be displayed on a vehicle that is required to be placarded for hazardous materials?

Accepted Answer

Four, on the front, rear, and both sides — A placarded load must carry at least four matching placards, placed on the front, the rear, and each side.

Answer

One, mounted only at the rear

Answer

Two, one on each side

Answer

Six, spaced evenly around the trailer

Question 2

When the red lights at a highway-rail crossing start flashing, what does this signal tell a commercial driver?

Accepted Answer

Stop and yield, because a train is approaching — Flashing red lights mean a train is coming, so you must stop and yield the right-of-way before crossing.

Answer

Hurry across before the train can reach the crossing

Answer

Treat the lights as advisory and creep through slowly

Answer

Keep moving at the same speed if no gate has lowered

Question 3

A small sign is mounted below a crossbuck at a grade crossing. What information does that lower sign give?

Accepted Answer

The number of tracks at that crossing — When a crossing has more than one set of rails, a sign beneath the crossbuck states how many tracks there are.

Answer

The weight limit for the roadway ahead

Answer

The posted speed limit for trucks

Answer

The distance to the next crossing

Question 4

On hazardous-materials shipping papers and placards, the four-digit identification number is preceded by which letters?

Accepted Answer

NA or UN — The four-digit identification code that first responders use is prefixed with the letters NA or UN.

Answer

DOT or FMC

Answer

US or CA

Answer

HM or HZ

Question 5

On a mountain downgrade you pass a sign reading 'Maximum Safe Speed.' How should a commercial driver treat the speed shown?

Accepted Answer

As the fastest speed you are permitted to drive there — Where a maximum safe speed is posted for a grade, you must never travel faster than that figure.

Answer

As a suggestion you may exceed with a loaded trailer

Answer

As a figure that applies only to passenger cars

Answer

As a minimum speed you must maintain down the grade

Question 6

What is the purpose of the diamond-shaped hazard labels a shipper attaches near hazardous cargo?

Accepted Answer

They warn people of the hazard class of the shipment — The diamond-shaped labels communicate the risk of the material so dockworkers and drivers know what hazard is present.

Answer

They record the weight of the package for billing

Answer

They show the delivery address for the freight

Answer

They mark which side of the trailer to unload first

Question 7

A round sign showing a black railroad-crossing symbol on a yellow background appears ahead of the tracks. What is it telling a commercial driver to do?

Accepted Answer

Slow down, look and listen for a train, and be prepared to stop if one is approaching — The round advance warning sign tells you to ease off the throttle, watch and listen for a train, and be ready to halt at the tracks if one is coming.

Answer

Accelerate to clear the area before any possible train arrives

Answer

Come to a full stop on every approach whether or not a train is near

Answer

Ignore the crossing unless a gate has already dropped

Question 8

You approach a slow farm tractor displaying a triangular emblem with a red border and an orange center. What does this symbol indicate?

Accepted Answer

The vehicle moves much slower than normal traffic — The red-and-orange triangle is the slow-moving vehicle emblem, warning that the vehicle ahead travels well below normal traffic speed.

Answer

The vehicle is transporting hazardous materials

Answer

The vehicle is disabled and about to be towed

Answer

The vehicle is a wide load requiring an escort

Question 9

States that have adopted move-over rules post roadside signs about them. What action do these laws call for when you approach a stopped emergency vehicle?

Accepted Answer

Slow down and, if safe, move over to a non-adjacent lane — Move-over laws require you to slow down and, when it is safe, shift into a lane that is not next to the stopped emergency vehicle or work area.

Answer

Speed up so you clear the scene as fast as possible

Answer

Stop completely in your lane until an officer waves you on

Answer

Sound your horn continuously as you pass the vehicle

Question 10

On a two-lane road you see an 'X' painted on the pavement together with the letters 'RR'. What does this marking warn of?

Accepted Answer

A railroad crossing ahead, the same warning the advance sign gives — Pavement markings that show an X with the letters RR carry the same message as the advance warning sign: a railroad crossing lies ahead.

Answer

A rest area set aside for railroad employees

Answer

The end of a legal passing zone for cars

Answer

An exit lane leading to a weigh station

Question 11

What does a crossbuck sign posted at a highway-rail grade crossing require of you?

Accepted Answer

Yield the right-of-way to any train that is approaching — The crossbuck marks the grade crossing and directs you to give the right-of-way to any train that is coming.

Answer

Stop for a fixed thirty seconds before proceeding

Answer

Sound your horn twice whether or not a train is present

Answer

Back away from the tracks until any signal clears

Question 12

At a crossing fitted with gates and flashing lights, when may a driver proceed across the tracks?

Accepted Answer

Only after the gates are fully raised, the lights stop, and it is safe — You must remain stopped until the gates rise fully and the lights quit flashing, then cross only when it is clearly safe.

Answer

As soon as the gate begins to lift, even if lights still flash

Answer

Immediately, if you can fit under the descending gate arm

Answer

Whenever the vehicle ahead has already driven around the gate

Road Signs

Study questions with answers

1. How many identical placards must be displayed on a vehicle that is required to be placarded for hazardous materials?

2. When the red lights at a highway-rail crossing start flashing, what does this signal tell a commercial driver?

3. A small sign is mounted below a crossbuck at a grade crossing. What information does that lower sign give?

4. On hazardous-materials shipping papers and placards, the four-digit identification number is preceded by which letters?

5. On a mountain downgrade you pass a sign reading 'Maximum Safe Speed.' How should a commercial driver treat the speed shown?

6. What is the purpose of the diamond-shaped hazard labels a shipper attaches near hazardous cargo?

7. A round sign showing a black railroad-crossing symbol on a yellow background appears ahead of the tracks. What is it telling a commercial driver to do?

8. You approach a slow farm tractor displaying a triangular emblem with a red border and an orange center. What does this symbol indicate?

9. States that have adopted move-over rules post roadside signs about them. What action do these laws call for when you approach a stopped emergency vehicle?

10. On a two-lane road you see an 'X' painted on the pavement together with the letters 'RR'. What does this marking warn of?

11. What does a crossbuck sign posted at a highway-rail grade crossing require of you?

12. At a crossing fitted with gates and flashing lights, when may a driver proceed across the tracks?

More CDL — General Knowledge topics

Practice Road Signs in another state