Traffic Laws & Road Safety Rules Flashcards

Under federal regulations, what is the maximum allowable blood alcohol concentration (BAC) for a CDL holder operating a commercial vehicle?

Answer: 0.04%

Federal law sets the BAC limit for CDL drivers operating CMVs at 0.04%, half the limit for non-commercial drivers.

A driver trainer notices a student hesitates before entering a roundabout. Which is the correct rule for yielding in a roundabout?

Answer: Entering vehicles yield to vehicles already circulating inside

Vehicles entering a roundabout must yield to all traffic already circulating within it.

A school bus has stopped with red lights flashing on a two-lane undivided road. What must the following vehicle do?

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.

What does a yellow X signal above a lane on an expressway indicate to drivers?

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.

When must a driver use low-beam headlights instead of high beams while following another vehicle?

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.

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?

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.

According to the Uniform Vehicle Code, which action is required before a driver changes lanes on a multi-lane highway?

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.