Keep left
Drivers must pass to the left of the sign or obstruction.
Verified as Thai road sign บ.40 from Thai Department of Land Transport sign series on 2026-05-15.
Study guide
Connect this sign to practice
Keep left sets a positive obligation, and exam questions usually probe two things: when it starts and what would override it. Practising it in the question flow makes both crisp.
Now see it in questions.
Spotting Keep 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.
