No changing lanes to the left
Drivers must not change lanes to the left where this sign is posted. Stay in the current lane until the restriction ends or another sign allows the lane change.
Verified as Thai road sign บ.10 from Department of Rural Roads sign series on 2026-05-15.
Study guide
Connect this sign to practice
No changing lanes to the left is a "don't", and the Thai exam likes to probe the until-when part: where the prohibition lifts, what overrides it, and whether common driver workarounds are still legal. Practising it in context makes the answer obvious.
Now see it in questions.
Spotting No changing lanes to the left in isolation is one thing. Recognising it inside a real exam-style question, among lookalikes and trick wording, is another. The diagnostic mixes it in for you.
