You may not cross a single broken white or yellow line:
- When doing so would interfere with traffic. ✓
- When turning left into a driveway.
- When the car in front of you is disabled.
- When passing to the right on a one-way street.
Answer: A. When doing so would interfere with traffic.
You may not cross a single broken white or yellow line when doing so would interfere with traffic.
Why this is the answer
The handbook says a single broken white line may be crossed to change lanes only when it is safe, and a single broken yellow line may be crossed to pass only when it is safe. A move that interferes with traffic is not a safe move, so the broken line does not give you a right to cross regardless of other drivers. The line permits a lane change or pass; it does not cancel your need to wait for a safe gap.
Why the other answers are wrong
- B. When turning left into a driveway. — The passages allow a left turn across certain double yellow lines when safe, but they do not say a single broken line lets you turn into a driveway even when traffic would be affected.
- C. When the car in front of you is disabled. — The passages give no special permission to cross a single broken line because the car ahead is disabled; the safe-crossing condition still applies.
- D. When passing to the right on a one-way street. — The passages do not describe passing on the right on a one-way street as an exception to the safe-crossing rule for a single broken line.
Remember it
A broken line says you may cross, not that you may cut someone off; cross only when the lane is clear.