You may not cross a single broken white (or yellow) line:
- When to do so would interfere with traffic ✓
- When turning left into a driveway
- When the car in front is disabled
- When passing to the right on a one-way street
Answer: A. When to do 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 line means you can pass other vehicles or change lanes only if you can do it safely and without interfering with traffic. So the line itself does not forbid crossing it. The limit is whether crossing would get in the way of other traffic. That makes interfering with traffic the condition under which you may not cross.
Why the other answers are wrong
- B. When turning left into a driveway — A left turn into a driveway is described as an exception to certain solid-line rules, not as the condition that limits crossing a single broken line.
- C. When the car in front is disabled — The passages do not list a disabled car ahead as a reason to cross a single broken line; the stated limit is whether crossing would interfere with traffic.
- D. When passing to the right on a one-way street — Passing to the right on a one-way street is not covered in these passages, so it is not the stated restriction for crossing a single broken line.
Remember it
Treat a broken line as permission that still depends on safety: other traffic comes first.