CDT Traffic Laws & Road Safety Rules 2 — Questions and Answers
Question 1: Under federal regulations, what is the maximum allowable blood alcohol concentration (BAC) for a CDL holder operating a commercial vehicle?
- 0.08%
- 0.04% (Correct answer)
- 0.02%
- 0.00%
Correct answer: 0.04%
Federal law sets the BAC limit for CDL drivers operating CMVs at 0.04%, half the limit for non-commercial drivers.
Question 2: A driver trainer notices a student hesitates before entering a roundabout. Which is the correct rule for yielding in a roundabout?
- Vehicles inside the roundabout yield to entering vehicles
- Entering vehicles yield to vehicles already circulating inside (Correct answer)
- The vehicle on the right always has the right of way
- Traffic signals inside the roundabout control priority
Correct answer: Entering vehicles yield to vehicles already circulating inside
Vehicles entering a roundabout must yield to all traffic already circulating within it.
Question 3: A school bus has stopped with red lights flashing on a two-lane undivided road. What must the following vehicle do?
- Slow to 15 mph and pass cautiously
- Stop at least 20 feet away and wait until the lights stop flashing (Correct answer)
- Stop only if children are visible outside the bus
- Proceed if no children are crossing
Correct answer: Stop at least 20 feet away and wait until the lights stop flashing
All vehicles on both sides of a two-lane road must stop at least 20 feet from a stopped school bus with flashing red lights.
Question 4: What does a yellow X signal above a lane on an expressway indicate to drivers?
- Prepare to merge left
- The lane is open for use
- Move out of the lane — it is closing or closed (Correct answer)
- High-occupancy vehicle lane ahead
Correct answer: Move out of the lane — it is closing or closed
A yellow X warns that the lane is about to close; drivers should move to an adjacent open lane immediately.
Question 5: When must a driver use low-beam headlights instead of high beams while following another vehicle?
- Within 500 feet (Correct answer)
- Within 400 feet
- Within 300 feet
- Within 200 feet
Correct answer: Within 500 feet
Most states require drivers to dim high beams to low beams when following another vehicle within 500 feet to avoid blinding the driver ahead.
Question 6: A driver trainer is teaching about speed limits in school zones. In most US states, what is the typical posted speed limit in an active school zone?
- 10 mph
- 15 mph
- 25 mph (Correct answer)
- 35 mph
Correct answer: 25 mph
The most common school zone speed limit in the US is 25 mph when children are present, though some states use 15 mph.
Question 7: According to the Uniform Vehicle Code, which action is required before a driver changes lanes on a multi-lane highway?
- Sound the horn to alert adjacent vehicles
- Signal, check mirrors, and check blind spots before moving (Correct answer)
- Signal for at least 500 feet and then move
- Only check mirrors — blind spots are the other driver's responsibility
Correct answer: Signal, check mirrors, and check blind spots before moving
Safe lane changes require signaling, checking all mirrors, and performing a physical blind-spot check before moving.
CDT Traffic Laws & Road Safety Rules 2
Under federal regulations, what is the maximum allowable blood alcohol concentration (BAC) for a CDL holder operating a commercial vehicle?